Journals >Collection Of theses on high power laser and plasma physics
Contents
2016
Volume: 14 Issue 1
46 Article(s)
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Research Article
Focusing properties of phase-only generalized Fibonacci photon sieves
Jie Ke, and Junyong Zhang
We propose a new algorithm to extend the standard Fibonacci photon sieve to the phase-only gen-eralized Fibonacci photon sieve (GFi PS) and find that the focusing properties of the phase-only GFi PS are only relevant to the characteristic roots of the recursion relation of the generalized Fibonacci sequences. By switchWe propose a new algorithm to extend the standard Fibonacci photon sieve to the phase-only gen-eralized Fibonacci photon sieve (GFi PS) and find that the focusing properties of the phase-only GFi PS are only relevant to the characteristic roots of the recursion relation of the generalized Fibonacci sequences. By switching the transparent and opaque zones on the basis of the generalized Fibonacci sequences, we not only realize adjustable bifocal lengths, but also give their corresponding analytic expressions. Besides, we investigate a special phase-only GFi PS, a spiral-phase GFi PS, which can present twin vortices along the axial coordinate. Compared with the single focusing system, bifocal system can be exploited to enhance the processing speed, and offer a broad range of applications, such as direct laser writing, optical tweezers or atom trapping and paralleled fluorescence microscope..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 34 (2016)
Study on Beam Positioning Stability of Optical System by Optical-Electro Test Method
ZHENG Liu-nian, HUANG Hong-biao, LIU Zhi-gang, and PANG Xiang-yang
Based on the vibration theory and the matrix optics theory, the principle of the optical image method to test the beam positioning stability is derived. The test method of beam positioning stability is designed, and the experimental results show that the optical image method can accurately analyze the range of the beamBased on the vibration theory and the matrix optics theory, the principle of the optical image method to test the beam positioning stability is derived. The test method of beam positioning stability is designed, and the experimental results show that the optical image method can accurately analyze the range of the beam positioning stability error, also can analyze the value and influence degree of vibration frequency of the error, and combined with the accelerometer by the electron test method, the source of the error can be detected in the optical system. The optical-electro test method is reliable, simple and convenient, and has good engineering application value, especially for large optical system..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 68 (2016)
Compensation method for temperature-induced phase mismatch during frequency conversion in high-power laser systems
ZIJIAN CUI, DEAN LIU, MEIZHI SUN, JIE MIAO, and JIANQIANG ZHU
A compensation method for phase mismatch caused by temperature variation during the frequency conversion process is proposed and the theoretical model is established. The method is based on the principle that phase mismatch can be compensated via the electro-optic effect based on a compensation scheme consisting of twoA compensation method for phase mismatch caused by temperature variation during the frequency conversion process is proposed and the theoretical model is established. The method is based on the principle that phase mismatch can be compensated via the electro-optic effect based on a compensation scheme consisting of two nonlinear crystals and an electro-optic crystal; further, a new dimension adjustment can be achieved by changing the voltage. In a proof-of-principle study, frequency conversion from 1053 nm to 526.5 nm and 351 nm by cascade KH2PO4 (KDP) and KD2PO4 (DKDP) crystals, respectively, is presented as an example. Three-dimensional numerical simulations are conducted to show that the conversion efficiency of frequency doubling and tripling varies with temperature. The results show that the temperature acceptance bandwidth of doubling and tripling can be 2.4 and 3.4 times larger, respectively, than that of the traditional method using a single crystal. We also analyze the stability of the conversion efficiency for 192 beams by our proposed method when the temperature is randomly varied within the range of 24°C–26°C. The standard deviation of the conversion efficiency of frequency doubling and tripling decreases from 1.25% and 6.61% to 0.18% and 0.56%, respectively. In addition, the influence of the reflection loss on the output efficiencies is also analyzed and the results show that it is very small. This indicates that this method may be effective in reducing the temperature sensitivity of conversion efficiency..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 525 (2016)
Array illumination of a Fresnel–Dammann zone plate
YAYAO MA, CHAOCHAO YE, JIE KE, JUNYONG ZHANG, JIANQIANG ZHU, and ZUNQING LING
The traditional Dammann grating is a phase-only modulation, and its theoretical foundation is based on far-field diffraction. Here we extend the traditional Fresnel zone plate (FZP) into a Fresnel–Dammann zone plate (FDZP), which is, in essence, considered as a FZP with Dammann modulation. Different from the Dammann grThe traditional Dammann grating is a phase-only modulation, and its theoretical foundation is based on far-field diffraction. Here we extend the traditional Fresnel zone plate (FZP) into a Fresnel–Dammann zone plate (FDZP), which is, in essence, considered as a FZP with Dammann modulation. Different from the Dammann grating, a single FDZP can generate array illumination from the near field to the far field by means of amplitude-only modulation in the absence of phase modulation. We then give some array illuminations operated in a water window to validate the feasibility and validity. This kind of wave-front modulation technology can be applied to array focusing and imaging from the x-ray to the EUV region..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 7218 (2016)
On-shot laser beam diagnostics for high-power laser facility with phase modulation imaging
X Pan, S P Veetil, C Liu, H Tao, Y Jiang, Q Lin, X Li, and J Zhu
A coherent-modulation-imaging-based (CMI) algorithm has been employed for on-shot laser beam diagnostics in high-power laser facilities, where high-intensity short-pulsed lasers from terawatt to petawatt are designed to realize inertial confinement fusion (ICF). A single-shot intensity measurement is sufficient for wavA coherent-modulation-imaging-based (CMI) algorithm has been employed for on-shot laser beam diagnostics in high-power laser facilities, where high-intensity short-pulsed lasers from terawatt to petawatt are designed to realize inertial confinement fusion (ICF). A single-shot intensity measurement is sufficient for wave-front reconstruction, both for the near-field and far-field at the same time. The iterative reconstruction process is computationally very efficient and was completed in dozens of seconds by the additional use of a GPU device to speed it up. The compact measurement unit—including a CCD and a piece of pre-characterized phase plate—makes it convenient for focal-spot intensity prediction in the target chamber. It can be placed almost anywhere in high-power laser facilities to achieve near-field wave-front diagnostics. The feasibility of the method has been demonstrated by conducting a series of experiments with diagnostic beams and seed pulses with deactivated amplifiers in our highpower laser system..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 55001 (2016)
Stability of the Sol Gel Silica Antireflective Film Heat Treated at High and Low Temperature
Shen Bin, Li Haiyuan, Xiong Huai, Zhang Xu, and Tang Yongxing
The silica suspension was prepared by a sol gel method using tetraethylorthosilicate (TEOS) as precursor and ethanol as solvent. The stability of the sol system was observed by particle size test. The particle size maintained at about 6.5 nm for 4 months. The quartz substrates were coated by a dipping method and heat tThe silica suspension was prepared by a sol gel method using tetraethylorthosilicate (TEOS) as precursor and ethanol as solvent. The stability of the sol system was observed by particle size test. The particle size maintained at about 6.5 nm for 4 months. The quartz substrates were coated by a dipping method and heat treated at 200 ℃ and 800 ℃ in a muffle burner. The film transmittance curve moves to short wavelength direction by about 210 nm, and both the transmittance peaks are more than 99.8%. Therefore, the film’ optical properties are excellent. The stabilities of film heat treated at different temperatures were researched in different humidity environments. The transmittances of the films heat treated at 200 ℃ are more than 99.9% and the wavelength of film transmittance peak decreases by about 150 nm. The transmittances of the films heat treated at 800 ℃ reduces by 0.3% and the wavelength of film transmittance peak maintain at 600 nm..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 198 (2016)
High Precision and Large Range Timing Jitter Measurement and Control of Ultrashort Laser Pulses
Yong Cui, Yanqi Gao, Zexi Zhao, Daxing Rao, Zhongyang Xu, Ning An, Jiong Shan, Dawei Li, Jianwei Yu, Tao Wang, Guang Xu, Weixin Ma, and Yaping Dai
An attosecond precision and femtosecond range timing jitter measurement and control technique is proposed. It is based on the modulation of the combined pulse induced by relative time delay of individual pulses. The core of this timing jitter detection method is the integrated technique of optical cross correlation andAn attosecond precision and femtosecond range timing jitter measurement and control technique is proposed. It is based on the modulation of the combined pulse induced by relative time delay of individual pulses. The core of this timing jitter detection method is the integrated technique of optical cross correlation and electrical energy interferometry. To illustrate this technique, a proof-of-principle experiment is demonstrated based on two 237 fs pulses. The peak-to-valley timing jitter of the two pulses to be combined is less than 700 as in 1 h and the average efficiency of coherent beam combining could reach to 91.6%..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 2215 (2016)
Optical field distribution on a hohlraum wall during indirectlaser-driven inertial confinement fusion
Lei Ren, Kewei You, Zhaoyang Jiao, and Jianqiang Zhu
A model to calculate the optical field distribution of quadruplet beams on a hohlraum target wall is pre-sented. This model combines geometrical ray tracing, coordinate transformation, and Fresnel diffractionintegral to capture the quadruplet beams propagating in four different directions and the typically non-planar gA model to calculate the optical field distribution of quadruplet beams on a hohlraum target wall is pre-sented. This model combines geometrical ray tracing, coordinate transformation, and Fresnel diffractionintegral to capture the quadruplet beams propagating in four different directions and the typically non-planar geometry of the hohlraum wall. The results demonstrate that the optical field distribution arisesmainly from individual beam diffraction, and the interference with other beams in the quadruplet hardlydevotes to the distribution. A movie is also produced to interpret the spatio and temporal evolution ofthe optical field on a cylindrical hohlraum wall..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 3629 (2016)
Noncritically phase-matched fourth-harmonic generation of Nd:glass lasers and design of final optics assembly
XIUQING JIANG, LAILIN JI, DONG LIU, SHUNXING TANG, BAOQIANG ZHU, and ZUNQI LIN
The noncritically phase-matched (NCPM) fourth-harmonic generation (FHG) with partially deuterated dihydrogen phosphate (KD*P) crystal at an Nd:glass laser radiation wavelength of 1053.1 nm has been confirmed. NCPM FHG has been achieved in 70% and 65% deuterated KD*P crystal at the temperature of 17.7°C and 29.3The noncritically phase-matched (NCPM) fourth-harmonic generation (FHG) with partially deuterated dihydrogen phosphate (KD*P) crystal at an Nd:glass laser radiation wavelength of 1053.1 nm has been confirmed. NCPM FHG has been achieved in 70% and 65% deuterated KD*P crystal at the temperature of 17.7°C and 29.3°C, respectively. The angular acceptance of 70% and 65% deuterated KD*P crystals fixed at their NCPM temperature were measured, which were 53 and 55 mrad, respectively. The application of the NCPM FHG in a high-power laser facility for inertial confinement fusion is also discussed. Based on the theoretical analysis, the NCPM KD*P can be placed after the focus lens; thus, the laser-induced damage of a fused-silica lens at ultraviolet can be avoided..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 4132 (2016)
Temporal characterization of petawatt class laser at Shen Guang II facility
XIAOPING OUYANG, YONG CUI, JIAN ZHU, BAOQIANG ZHU, and JIANQIANG ZHU
Temporal characterization is important to diagnose and measure a petawatt (PW) class laser. We obtained the V curve of the pulse width versus the grating position using pulse width measurement with a mirror image configuration. The temporal range for pulse width was 18 ps with a resolution of 0.05 ps. We measured the pTemporal characterization is important to diagnose and measure a petawatt (PW) class laser. We obtained the V curve of the pulse width versus the grating position using pulse width measurement with a mirror image configuration. The temporal range for pulse width was 18 ps with a resolution of 0.05 ps. We measured the pulse contrast between the -60 ps and -6 ps PW class laser within a single shot in the Shen Guang II facility. We measured the pulse contrast between the -91 ps and -60 ps PW class laser after expanding the temporal range. The temporal range was 70 ps, with a dynamic range of eight orders of magnitude..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 7538 (2016)
Suppression of FM-to-AM modulation by polarizing fiber front end for high-power lasers
ZHI QIAO, XIAOCHAO WANG, WEI FAN, XUECHUN LI, YOUEN JIANG, RAO LI, CANHONG HUANG, and ZUNQI LIN
FM-to-AM modulation is an important effect in the front end of high-power lasers that influences the temporal profile. Various methods have been implemented in standard-fiber and polarization-maintaining (PM)-fiber front ends to suppress the FM-to-AM modulation. To analyze the modulation in the front end, a theoreticalFM-to-AM modulation is an important effect in the front end of high-power lasers that influences the temporal profile. Various methods have been implemented in standard-fiber and polarization-maintaining (PM)-fiber front ends to suppress the FM-to-AM modulation. To analyze the modulation in the front end, a theoretical model is established and detailed simulations carried out that show that the polarizing (PZ) fiber, whose fast axis has a large loss, can successfully suppress the modulation. Moreover, the stability of the FM-to-AM modulation can be improved, which is important for the front end to obtain a stable output. To verify the model, a PZ fiber front end is constructed experimentally. The FM-to-AM modulation, without any compensation, is less than 4%, whereas that of the PM fiber front end with the same structure is nearly 20%. The stability of the FM-to-AM modulation depth is analyzed experimentally and the peak-to-peak and standard deviation (SD) are 2% and 0.38%, respectively, over 3 h. The experimental results agree with the simulation results and both prove that the PZ fiber front end can successfully suppress the FM-to-AM conversion. The PZ fiber front end is a promising alternative for improving the performance of the front end in high-power laser facilities..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 8352 (2016)
Influence of the neodymium glass parameters on the amplified spontaneous emission in slab amplifier
Bingyan Wang, Junyong Zhang, Yanli Zhang, Li wang, and Jianqiang Zhu
Amplified spontaneous emission (ASE) causes the decrease of the inverted population density and the nonuniformity of gain in slab amplifier for high power laser systems. In this paper, a three dimension model, based on the data in SG-II, in which the residual reflection in the cladding and the ASE process are taken intAmplified spontaneous emission (ASE) causes the decrease of the inverted population density and the nonuniformity of gain in slab amplifier for high power laser systems. In this paper, a three dimension model, based on the data in SG-II, in which the residual reflection in the cladding and the ASE process are taken into consideration, is built to analyze the space distribution and time evolution of small signal gain coefficient using Monte Carlo algorithm and ray tracing. This model has been verified by comparing with the experimental data. The traverse size of slab is 68.2cm×36.3cm, which is usually decided by the clear aperture and the manufacture. By means of the model, the impact of thickness, residual reflectivity and the stimulated cross section of neodymium glass to the ASE are analyzed in detail..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 9255 (2016)
Large-aperture laser beam alignment system based on far-field sampling technique
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Laser beam alignment is very important for high-power laser facility. Long laser path and large-aperture lens for alignment are generally used, while the proposed alignment system with a wedge by far-field sampling technique reduces both space and cost requirements. General alignment system for large-aperture laser beaLaser beam alignment is very important for high-power laser facility. Long laser path and large-aperture lens for alignment are generally used, while the proposed alignment system with a wedge by far-field sampling technique reduces both space and cost requirements. General alignment system for large-aperture laser beam is long in distance and large in volum because of taking near-field sampling technique. With the development of laser fusion facilities, the space for alignment system is limited. A new alignment system for large-aperture laser beam is designed to save space and reduce operating costs. The new alignment for large-aperture laser beam with a wedge is based on far-field sampling technique. The wedge is placed behind the spatial filter to reflect some laser beam as signal light for alignment. Therefore, laser beam diameter in alignment system is small, which can save space for the laser facility. Comparing to general alignment system for large-aperture laser beam, large-aperture lenses for near-field and far-field sampling, long distance laser path are unnecessary for proposed alignment system, which saves cost and space greatly. This alignment system for large-aperture laser beam has been demonstrated well on the Muliti-PW Facility which uses the 7th beam of the SG-Ⅱ Facility as pump source. The experimental results indicate that the average near-field alignment error is less than 1% of reference, and the average far-filed alignment error is less than 5% of spatial filter pinhole diameter, which meet the alignment system requirements for laser beam of Multi-PW Facility..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 10016 (2016)
High precision long-term stable fiber–based optical synchronization system
Yurong Li, Xiaochao Wang, Youen Jiang, Zhi Qiao, Rao Li, and Wei Fan
A fiber-based，high precision long-term stable time synchronization system for multi-channel laser pulses is presented，using fiber pulse stacker combined with high-speed optical-electrical conversion and electronics processing technology. This scheme is used to synchronize two individual lasers including a mode-lock lasA fiber-based，high precision long-term stable time synchronization system for multi-channel laser pulses is presented，using fiber pulse stacker combined with high-speed optical-electrical conversion and electronics processing technology. This scheme is used to synchronize two individual lasers including a mode-lock laser and a time shaping pulse laser system. The relative timing jitter between two laser pulses achieved with this system is 970 fs (rms) in five minutes and 3.5 ps (rms) in five hours. The synchronization system is low cost and can work at over several tens of MHz repetition rate..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 10019 (2016)
Spectral phase effects and control requirements of coherent beam combining for ultrashort ultrahigh intensity laser systems
YONG CUI, YAN-QI GAO, ZE-XI ZHAO, ZHONG-YANG XU, NING AN, DA-WEI LI, JIAN-WEI YU, TAO WANG, GUANG XU, WEI-XIN MA, and YA-PING DAI
Based on the premise that further improvements to the size and damage threshold of large-aperture optical components are severely limited, coherent beam combining (CBC) is a promising way to scale up the available peak power of pulses for ultrashort ultrahigh intensity laser systems. Spectral phase effects are importanBased on the premise that further improvements to the size and damage threshold of large-aperture optical components are severely limited, coherent beam combining (CBC) is a promising way to scale up the available peak power of pulses for ultrashort ultrahigh intensity laser systems. Spectral phase effects are important issues and have a significant impact on the performance of CBC. In this work, we analyze systematically factors such as spectral dispersions and longitudinal chromatism, and get the general spectral phase control requirements of CBC for ultrashort ultrahigh intensity laser systems. It is demonstrated that different orders of dispersion influence intensity shape of the combined beam, and high-order dispersions affect the temporal contrast of the combined beam, while the number of the channels to be combined has little impact on the temporal Strehl ratio (SR) of the combined beam. In addition, longitudinal chromatism should be controlled effectively since it has a detrimental effect on the combined beam at the focal plane, both temporally and spatially..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 10124 (2016)
Mitigation of beam sampling grating damage induced by upstream flaws in the final optics assembly
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The high fluence performance of high-power laser systems is set by optical damage, especially in the final optics assembly (FOA). The flaws on the frequency converter surface can cause optical intensity intensification and, therefore, damage the downstream optical elements, such as the beam sampling grating (BSG), whicThe high fluence performance of high-power laser systems is set by optical damage, especially in the final optics assembly (FOA). The flaws on the frequency converter surface can cause optical intensity intensification and, therefore, damage the downstream optical elements, such as the beam sampling grating (BSG), which is an important component in the FOA. Mitigation of BSG damage caused by flaws is discussed. Physical models are established to simulate the optical field enhancement on BSG modulated by the upstream flaw, considering both the linear and nonlinear propagation effects. Numerical calculations suggest that it is important to place the BSG in a properly selected position to mitigate the laser-induced damage. Furthermore, strict controls of flaw size, modulation depth, distance between frequency converter and focusing lens, and the thickness of the focusing lens are also significant to mitigate the BSG damage. The results obtained could also give some suggestions for damage mitigation of optical components and the layout design of the final optics assembly..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 11021 (2016)
Simulation study of broadband long-pulsed amplification in high-power laser systems
Hongchao Hui, Junyong Zhang, Xinghua Lu, Jiachen Zhang, Xin Chen, Xiuqing Jiang, Baoqiang Zhu, and Zunqi Lin
Accurately and efficiently predicting the fundamental-frequency temporal shape of broadband long-pulsed lasers is very important in research on the properties of high-power laser amplifiers. In this study, we first propose that analytic electric polarization in the temporal domain is applied to broadband long-pulsed puAccurately and efficiently predicting the fundamental-frequency temporal shape of broadband long-pulsed lasers is very important in research on the properties of high-power laser amplifiers. In this study, we first propose that analytic electric polarization in the temporal domain is applied to broadband long-pulsed pulse amplification. We first verify the accuracy of this algorithm in the dozens of picoseconds range and the results are consistent with Miro software. Then we simulate the broadband long-pulsed amplification. The simulation results indicate that the front edge of the output pulse is more enlarged than the end edge owing to saturation and that the gain narrowing induces severe amplitude modulation. Analytic electric polarization in the temporal domain is effective and precise for investigating the broadband pulse amplification in the time scale from dozens of picoseconds to nanoseconds, and the computation time can be decreased by at least 4 orders of magnitude..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 31405 (2016)
Far-field detection system for laser beam and crystal alignment
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Laser beam far-field alignment as well as frequency-doubling and frequency-tripling crystal adjustment is very important for high-power laser facility. Separate systems for beam and crystal alignment are generally used while the proposed approach by off-axial grating sampling share common optics for these two functionsLaser beam far-field alignment as well as frequency-doubling and frequency-tripling crystal adjustment is very important for high-power laser facility. Separate systems for beam and crystal alignment are generally used while the proposed approach by off-axial grating sampling share common optics for these two functions, reducing both space and cost requirements. This detection system has been demonstrated on the National Laser Facility of Israel. The experimental results indicate that the average far-field alignment error is <5% of the spatial filter pinhole diameter, average autocollimation angle error of crystals is <10 μrad, and average frequency-tripling conversion efficiency is 69.3%, which meet the alignment system requirements on the beam direction and crystals..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 36108 (2016)
High-energy square pulses and burst-mode pulses in an all-normal dispersion double-clad mode-locked fiber laser
Zhi Qiao, Xiaochao Wang, Chao Wang, Yuanyuan Jing, Wei Fan, and Zunqi Lin
A double-clad Yb-doped mode-locked fiber laser that can operate in burst-mode and square-pulse states is experimentally investigated. In the burst-mode state, a burst train with 55 pulses of 500 ps duration is obtained. In the square-pulse state, which is similar to noiselike pulses, the maximum pulse energy is 820 nJ A double-clad Yb-doped mode-locked fiber laser that can operate in burst-mode and square-pulse states is experimentally investigated. In the burst-mode state, a burst train with 55 pulses of 500 ps duration is obtained. In the square-pulse state, which is similar to noiselike pulses, the maximum pulse energy is 820 nJ and the duration can be tuned from 15.8 to 546 ns. The square pulses have a narrow and multipeak spectrum, which is quite different from that of normal noiselike pulses. The fiber laser promises an alternative formation mechanism for burst-mode and square-pulse mode-locked fiber lasers..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 52701 (2016)
Two approaches to three-dimensional array foci of generalized Fibonacci structures
Jie Ke, Junyong Zhang, and Zhiyuan Ren
We propose two technologies to extend the number of layers in order to complete the three-dimensional (3D) array diffraction-limited foci, which means there are two-dimensional array foci at multi-focal planes. One technology is the diffractive optical lever; the other is multi-hybrid Fibonacci structures. Based on theWe propose two technologies to extend the number of layers in order to complete the three-dimensional (3D) array diffraction-limited foci, which means there are two-dimensional array foci at multi-focal planes. One technology is the diffractive optical lever; the other is multi-hybrid Fibonacci structures. Based on the aperiodic Fibonacci structures and binary phase modulation, various kinds of devices can be designed to produce 3D array foci whose focusing properties approximately satisfy the mathematical characteristics of the Fibonacci sequences. With those technologies, the diffraction-limited array foci are freely designed or distributed as required at the desired multiple focal planes..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 60501 (2016)
Light intensity distribution of high-power laser beams on target plane under different focus system of 2×2 beam array
Sun Xiao-Yan, Lei Ze-Min, Lu Xing-Qiang, Lü Feng-Nian, Zhang Zhen, and Fan Dian-Yuan
Large aperture high-power laser drivers usually focus the high power laser beams in 2×2 quads to the target chamber center in order to increase the light intensity on the target plane. The large aperture wedged focus lenses are the core components in the focus system of quadruplets of beams, and it is thought possLarge aperture high-power laser drivers usually focus the high power laser beams in 2×2 quads to the target chamber center in order to increase the light intensity on the target plane. The large aperture wedged focus lenses are the core components in the focus system of quadruplets of beams, and it is thought possible to use four two-dimensional off-axis wedged focus lenses as four sub-lenses to make up a larger aperture wedged focus lens in form to focus the four beams. Given that the large aperture two-dimensional off-axis wedged focus lenses are processed and used difficultly, the wedged focus lenses are divided into three categories: the two-dimensional off-axis wedged focus lenses, the onedimensional off-axis wedged focus lenses, and the non-off-axis wedged focus lenses. On the basis of the three modes of the wedged focus lenses and the corresponding specific incidence angles of each sub-beam, the three focus schemes for the 2×2 beam array are put forward to comparatively research the light intensity distribution on the target plane. Research results show that from a perspective of the coherence among the four sub-beams, the phase factors of each sub-beam respectively introducing by the three focus systems with the two-dimensional off-axis, one-dimensional off-axis, and non-off-axis wedged focus lenses are asymmetric, asymmetric and symmetric inside each sub-beam, and symmetric, asymmetric and symmetric among the four sub-beams. Therefore, the wave front consistency of the four sub-beams decreases in the order of the focus systems with the non-off-axis, two-dimensional off-axis, and one-dimensional off-axis wedged focus lenses. The focus schemes with the non-off-axis wedged focus lenses for 2×2 beam array can get the narrowest main-lobe, the strongest peak-value intensity, the highest energy concentration ratio on the target plane, followed by the one-dimensional off-axis and two-dimensional off-axis wedged focus lenses. The off-axis mode of the wedged focus lenses not only increases the complexity in the course of processing and using, but also increases the main-lobe size, decreases the peak-value intensity and the energy concentration ratio, which obtains a weaker focusing characteristics than that of the non-off-axis mode of the wedged focus lenses. Research results can provide an important reference for the design of the focus system in the target area of high-power laser drivers..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 64203 (2016)
Lens-free coherent modulation imaging with collimated illumination
Hua Tao, Suhas P. Veetil, Xingchen Pan, Cheng Liu, and Jianqiang Zhu
We propose a lens-free coherent modulation imaging (CMI) method for reconstructing a general complex-valued wave field from a single frame of a diffraction pattern. A numerical Fourier transform is introduced in the iterative reconstruction process to replace the lens or zone plate used in the current CMI technique to We propose a lens-free coherent modulation imaging (CMI) method for reconstructing a general complex-valued wave field from a single frame of a diffraction pattern. A numerical Fourier transform is introduced in the iterative reconstruction process to replace the lens or zone plate used in the current CMI technique to adopt the constraint on the Fourier components of the exit wave field of the sample. While the complexity of the experimental setup is remarkably reduced by replacing the zone plate and additional accessories with the numerical processing, the energy fluence loss induced by the undesired diffraction orders of the zone plate can be also avoided. The feasibility of the proposed technique is verified experimentally with visible light..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 71203 (2016)
808-nm Optical Parametric Amplification Based on DKDP Crystals
Liang Xiao, Kang Jun, Sun Meizhi, Xie Xinglong, and Zhu Jianqiang
The optical parametric chirped pulse amplification (OPCPA) near the 800 nm wavelength has gained significant popularity in the recent years. This can be attributed to the development of laboratory-scale Ndglass lasers with their associated second harmonic generation (SHG), the mature nonlinear crystal growth technologyThe optical parametric chirped pulse amplification (OPCPA) near the 800 nm wavelength has gained significant popularity in the recent years. This can be attributed to the development of laboratory-scale Ndglass lasers with their associated second harmonic generation (SHG), the mature nonlinear crystal growth technology, and the commercialized mode-locked Tisapphire oscillator. In this study, the characteristics of the 808-nm centered broad bandwidth signal OPCPA based on potassium dideuterium phosphate (DKDP) crystals are investigated. The phase mismatch in DKDP crystals for different deuteration levels of 0~99% is studied and a numerical simulation of the high energy optical parameric amplification (OPA) process with the considerations of absorption and several high deuteration levels is presented. Results show that the broadband bandwidth OPCPA at 808 nm can be obtained when the deuteration level is more than 90%..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jul. 27, 2016
- Vol. 14, Issue 1, 81901 (2016)
Study on low-refractive-index sol-gel SiO2 antireflective coatings
Bin Shen, Haiyuan Li, Huai Xiong, Xu Zhang, and Yongxing Tang
A study on low-refractive-index SiO2 antireflective (AR) coatings by a sol-gel method is reported. Variations in the properties of the coatings are related to the molar ratios of ammonia to deionized water being changed in the process of preparing the sols. From the performance test results, the optimal ratio of the reA study on low-refractive-index SiO2 antireflective (AR) coatings by a sol-gel method is reported. Variations in the properties of the coatings are related to the molar ratios of ammonia to deionized water being changed in the process of preparing the sols. From the performance test results, the optimal ratio of the reactants necessary to prepare low-refractive-index SiO2 AR coatings is determined. Of all the SiO2 AR coatings, the lowest recorded refractive index is 1.16 at a wavelength of 700 nm. The largest water contact angle is 121.2°, and the peak transmittance is 99.95% at a wavelength of 908 nm. Furthermore, the sol used to deposit the film with the lowest refractive index is stable because of the narrow size distribution of its constituent particles..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 83101 (2016)
Attenuation of high rate in parameter measurement of high power laser
Chen Xin, Tang Shunxing, Guo Yajing, Jing Yuanyuan, Jiang Xiuqing, and Zhu Baoqiang
In high power laser beam parameters measurement, attenuation scheme with high rate is key to far-field measurement. The far-field optical measurement system was analyzed and diameter of 95% encircled energy was used as important evaluation criterion of far-field measurement system. Measurement error of far-field opticaIn high power laser beam parameters measurement, attenuation scheme with high rate is key to far-field measurement. The far-field optical measurement system was analyzed and diameter of 95% encircled energy was used as important evaluation criterion of far-field measurement system. Measurement error of far-field optical measurement system and effect of attenuation with high rate on far-field measurement results were analyzed. Principle of attenuation scheme with high rate was established. By changing parameters of high attenuation rate in condition of single parallel plate, a pair of parallel plates and a pair of wedge flaps by Virtual Lab, influence of attenuation on the far-field measurement system was simulated and analyzed deeply. According to measurement system for f=3 000 mm and F=10, best attenuation scheme with high rate is designed. Diameter of 95% encircled energy of far-field image is 45.5 ?滋m, or 3.54 times of diffraction limitation..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 106002 (2016)
Applications of Iterative Algorithm Based on Phase Modulation in High Power Laser Facilities
Pan Xingchen, Tao Hua, Liu Cheng, and Zhu Jianqiang
Coherent modulation imaging (CMI) based algorithm has been employed for on- shot laser beam diagnostics in high power laser facility and off- line measurement of large- scale optic element. A single- shot intensity measurement is sufficient for wave-front reconstruction after the random phase plate has been accurately Coherent modulation imaging (CMI) based algorithm has been employed for on- shot laser beam diagnostics in high power laser facility and off- line measurement of large- scale optic element. A single- shot intensity measurement is sufficient for wave-front reconstruction after the random phase plate has been accurately pre- characterized, and the iteration process can be finished in 30 seconds with the acceleration of graphics processing unit (GPU) device. Furthermore, a compact structure is also available after combining CCD and phase plate together, which can be placed almost anywhere of high power laser facilities. Series of experiments have been finished for focal-spot prediction, measurement of large-scale continuous phase plate, and on-shot wave-front reconstruction of seed pulse in our high power laser facility with amplifiers turned off. The flexibility of CMI for focal- spot prediction, on- shot wave- front diagnostic and off- line measurement of optic elements has been demonstrated for its characteristic. It has significant influence on the development of high power laser facilities as a new method for wave-front measurement and diagnostics..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 108001 (2016)
Research on Calculation of Gain Spatial Distribution for Main Amplifiers in Million Joules Laser Facility
Wang Bingyan, Zhang Junyong, Wang Li, Liu Qiang, and Zhu Jianqiang
A model which can simulate the pump dynamics process of the main amplifiers in million joules laser facility is built based on Monte Carlo algorithm and a ASAP software. The model contains 3D airspace and 1D time domain, and the evolution of the distribution of the energy in light pass surface in different pumping timeA model which can simulate the pump dynamics process of the main amplifiers in million joules laser facility is built based on Monte Carlo algorithm and a ASAP software. The model contains 3D airspace and 1D time domain, and the evolution of the distribution of the energy in light pass surface in different pumping time with complete absorption on cladding is calculated, which is the same with the results mentioned in previous articles proving the accuracy of the model. The comparisons of average small signal gain coefficient are made between the cases when the residual reflection in cladding is taken into consideration or not. The results show that there is no significant difference when residual reflectivity is below 0.05%. The value of calculated average small signal gain coefficient with residual reflection is 6 percentage smaller than the measured value(4.42/m), which results from the use of part approximation during the simulation, the unconsidered spectrum of spontaneous radiation,the subsurface damage in the actual Nd:phosphate glass and so on..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 214003 (2016)
Highly stable and self-started all-fiber Yb3+ doped fiber laser mode-locked by chirped pulse spectral filtering and nonlinear polarization evolution
Zhang Pan-Zheng, Wang Xiao-Chao, Li Jing-Hui, Feng Tao, Zhang Zhi-Xiang, Fan Wei, Zhou Shen-Lei, Ma Wei-Xin, Zhu Jian, and Lin Zun-Qi
Without discrete optical components influencing the fiber format, all-fiber mode-locked laser has tremendous potential practical applications due to its advantages of better stability, alignment free, and better compaction. All-fiber laser mode-locked by nonlinear polarization evolution (NPE) can obtain good performancWithout discrete optical components influencing the fiber format, all-fiber mode-locked laser has tremendous potential practical applications due to its advantages of better stability, alignment free, and better compaction. All-fiber laser mode-locked by nonlinear polarization evolution (NPE) can obtain good performances in terms of pulse duration and spectrum. But the effective saturable absorption mirror can be overdriven at high peak power, which leads to multiple pulses, limiting the output pulse energy. And there is a trade-off between avoiding overdriving the NPE and ease of self-starting. In addition, the polarization of the pulse propagating in a long fiber is so sensitive to the environment vibration that it is difficult to implement a stable lone-time operation. All-fiber ring laser mode-locked by NPE alone is analyzed and realized. The simulation results show that even a polarization vibration of /38 can break the mode-locking completely. Experimentally, after carefully adjusting, singlepulse mode-locking is achieved with the spectrum centered at 1053.4 nm and a maximum pulse energy of 82 pJ. But the output parameters change continually during operating. After 60 min, the mode-locking is broken. The conclusion is obtained that instability and unreliability of self-starting are inevitable for such a laser. Here, we show significant improvements of the pulse energy, operating stability, and self-starting reliability from an all-fiber Yb-doped mode-locked fiber laser. The laser is mode-locked by NPE combined with chirped pulse spectral filtering (CPSF). In order to easily self-start and stabilize mode locking, a spectral filter is employed in the all-normal group velocity dispersion NPE cavity to provide additional amplitude modulation. Combined effects of NPE and CPSF result in desirable pulse output, desirable operating stability, and reliable self-starting simultaneously. Stable mode-locking centered at 1053 nm is achieved with a 3 dB spectral bandwidth of 9.1 nm and pulse duration of 17.8 ps. The average output power is 66.9 mW at a repetition rate of 15.2 MHz, corresponding to a pulse energy of 4.25 nJ. Especially, high operating stability and easily one-button self-starting are achieved simultaneously. The fluctuations of output parameters including pulse energy, pulse duration, and spectrum are within 0.3% during 150-min operation. Self-starting reliability is tested. The testing time lasts two weeks. During the two weeks, the laser is turned off and turned on 48 times by using a power supplying button, without any adjustment. And the re-turned on intervals change randomly. Each time, the mode-locking can start itself. The repeatabilities of output parameters including pulse energy, pulse duration, and spectrum are within 0.55%..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 214207 (2016)
Optimization of Morphology of Laser Induced Damage Mitigation Pit on Silica Optical Component
Zhou Li, Jiang Youen, Wei Hui, Fan Wei, and Li Xuechun
Aiming at morphology of laser induced damage mitigation pit on the rear surface of 3ω silica optical component, the mitigated area and its downstream intensity distributions with different morphologies are simulated by finite-difference time-domain method (FDTD) and Rayleigh-Sommerfeld (R-S) diffraction integral methodAiming at morphology of laser induced damage mitigation pit on the rear surface of 3ω silica optical component, the mitigated area and its downstream intensity distributions with different morphologies are simulated by finite-difference time-domain method (FDTD) and Rayleigh-Sommerfeld (R-S) diffraction integral method, respectively. The results show that when the angle between the tangent line of endpoints on the section contour of the pit and incident light is over 70°, the maximum intensity inside the mitigated optics is less than 1.66, and mitigation effect is better than that of other angles. The maximum downstream intensities of a pit in shape of parabolic surface, cone and truncated cone are all less than 1.46 with an angle of 70° and a width of 200 μm. But when the width of pit increases to 1 mm, for instance, the maximum downstream intensity is as high as 9.31 and area with high intensity covers a long range. Thus, taking the difficulty of laser machining technology into account, a conical pit with an angle larger than 70° is the first choice for the damage mitigation on the rear surface of silica optical component..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 602009 (2016)
Research Status and Development Trend of PIE Imaging Method
Yao Yudong, Liu Cheng, Pan Xingchen, Tao Hua, Wang Haiyan, and Zhu Jianqiang
As a newly developed lensless imaging technique, PIE (ptychographical iterative engine) does not only maintain the simplicity and convenience of the equipment of traditional coherent diffraction imaging (CDI) methods, but also overcomes the drawbacks such as restricted field of view and slow convergence. With the extenAs a newly developed lensless imaging technique, PIE (ptychographical iterative engine) does not only maintain the simplicity and convenience of the equipment of traditional coherent diffraction imaging (CDI) methods, but also overcomes the drawbacks such as restricted field of view and slow convergence. With the extensible imaging field, better convergence speed and higher immunization capability to noise, PIE is widely researched and used in optical, X-ray and electron beam imaging fields. PIE is a new method which is possible to replace the current phase imaging methods. The background, development, applications, problems and developing trend of the PIE method are introduced..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 609001 (2016)
Fast Shape Prediction in Multi-Pass Amplifier of High Power Laser System
Zhang Yanli, Zhang Junyong, You Kewei, Ma Weixin, Zhu Jian, Liu Dean, and Zhu Jianqiang
Three-dimensional spatio-temporal variation characteristics of pulse intensity is numerically simulated in detail in multi-pass amplifier of high power laser system. Theoretical calculation indicates that the complicated spatio-temporal distortion occurs as the pulse with specific spatio-temporal distribution passes thThree-dimensional spatio-temporal variation characteristics of pulse intensity is numerically simulated in detail in multi-pass amplifier of high power laser system. Theoretical calculation indicates that the complicated spatio-temporal distortion occurs as the pulse with specific spatio-temporal distribution passes the amplifier. This change imposes some difficulties on shaping prediction of the pulse power. The curve fitting method of input-output integral energy is proposed to achieve the inverse prediction of inject pulse shape formulti-pass amplifier system with high precision. The better prediction result is achieved not only for square pulse shape but also for multiple-steps complex pulse output, the relative power deviation reaches up to 0.032% for the square pulse output, and 0.78% for multiple-steps complex pulse output. In addition, the inverse prediction of more complicated Haan pulse is achieved. The relative power deviation is 0.13%. This method has not only high precision but also rapid computation and strong applicability..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 714001 (2016)
Online Monitoring and Adjusting Method for Misaligned Gratings of Optical Pulse Compressor
Xia Suqiu, Yang Qingwei, Shi Shuaixu, Xie Xinglong, and Zhu Jianqiang
To solve the misaligned grating problem in the double-pass single-parallel two-grating compressor system, a monitoring system with simple structure is designed. Numerical simulation is investigated based on the system scheme and an original method for online adjusting gratings is proposed. All dimensions of two misaligTo solve the misaligned grating problem in the double-pass single-parallel two-grating compressor system, a monitoring system with simple structure is designed. Numerical simulation is investigated based on the system scheme and an original method for online adjusting gratings is proposed. All dimensions of two misaligned gratings are analyzed and then separated to adjust step by step based on the relationship between monitoring variables and misadjustment until the misaligned gratings in the vacuum chamber have been adjusted back to the ideal position. The alignment error and reliability discussion of the method are presented. Based on the existed parameters of the system, the accuracy range from 0.30 μrad to 2.78 μrad is obtained..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 801002 (2016)
Spectrum Control Based on All-Fiber Multi-Pass Phase Modulation Structure
Jing Yuanyuan, Wang Xiaochao, Qiao Zhi, Li Yurong, and Fan Wei
A method of controlling spectrum based on all-fiber multi-pass phase modulation is demonstrated experimentally and theoretically. Numerical simulation results indicate that modulation times, modulation depth, shape and width of the modulation signal and synchronized precision between optical pulse and modulation signalA method of controlling spectrum based on all-fiber multi-pass phase modulation is demonstrated experimentally and theoretically. Numerical simulation results indicate that modulation times, modulation depth, shape and width of the modulation signal and synchronized precision between optical pulse and modulation signal have influences on the central wavelength, bandwidth as well as the shape of the output spectrum. The input spectrum with bandwidth of 0.03 nm is broadened into 2.238 nm after multi-pass phase modulation, and the experimental results match well with the simulation results. The corresponding relationship between the modulation signal waveforms with different phases and the output spectra is obtained, and the feasibility of the spectral characteristics control is verified..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 801004 (2016)
High Power Laser Multi-Parameter Measurement Technique Based on Integrating Sphere
Chen Xin, Tang Shunxing, Hui Hongchao, Liu Daizhong, Ouyang Xiaoping, Lin Qiang, and Zhu Baoqiang
Aiming at the disadvantage that the traditional measurement technique is sensitive to the incident direction of incident light, a beam-split technique of high power laser multi-parameter measurement based on integrating sphere is proposed. Numerical analysis and simulation about attenuation rate, time waveform of emergAiming at the disadvantage that the traditional measurement technique is sensitive to the incident direction of incident light, a beam-split technique of high power laser multi-parameter measurement based on integrating sphere is proposed. Numerical analysis and simulation about attenuation rate, time waveform of emergent light, and time waveform recovery of incident light are carried out by Monte-Carlo method, which validate the feasibility that the integrating sphere can be used as beam-splitter in laser measurement system. The energy and time waveform of nanosecond laser is measured based on integrating sphere. The theoretical analysis matches well with the experiment result. Experiment and simulation results show that spectrum parameter, energy parameter and time parameter of incident light can be recovered by measuring the parameters of the emergent light, when the light-split technique is used in laser parameters measurement. The proposed technique can conquer the disadvantage that the incident direction of incident light has great influence on the parameters of the emergent light in traditional technique. The proposed technical proposal possesses small volume and is easy to integrate, which can be used in modular design of multiple beam high power laser parameters measurement system..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 804002 (2016)
Depth Resolved Imaging by 3PIE with Dual-Beam Illumination
Chen Wen, Jiang Zhilong, Liu Cheng, and Zhu Jianqiang
In the single-beam illuminating 3PIE (ptychographic iterative engine) method, the specimen is vertically illuminated without considering the influence of oblique illumination on the reconstruction result. In this paper, a dual-beam illuminating 3PIE method is proposed on the basis of the single-beam illuminating 3PIE mIn the single-beam illuminating 3PIE (ptychographic iterative engine) method, the specimen is vertically illuminated without considering the influence of oblique illumination on the reconstruction result. In this paper, a dual-beam illuminating 3PIE method is proposed on the basis of the single-beam illuminating 3PIE method, and the simulation result shows that the reconstructed images are influenced by the phase inclination factor of the initial guessed illumination light beam. In the process of iterative recovery by the proposed method, two light beams are used to update the complex amplitude distribution of the same specimen area. The proposed method is demonstrated theoretically and experimentally. The results verify that the method can improve the convergence speed while weakening crosstalk between different specimen slices, and it is suitable for three-dimensional depth resolved imaging..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 811002 (2016)
Simulation and Optimization of Internal Flow Field in High Power Laser Slab Amplifiers
Yang Xiaowei, Liu Zhigang, Ren Zhiyuan, Zhang Haiqing, and Zhu Jianqiang
The cleanliness of neodymium glass surface in the slab amplifier is a key indicator of guaranteeing high performance and long lifetime of amplifiers, and the reasonable internal flow field distribution is the prerequisite for keeping clean in the amplifier cavity. By means of computational fluid dynamics method and witThe cleanliness of neodymium glass surface in the slab amplifier is a key indicator of guaranteeing high performance and long lifetime of amplifiers, and the reasonable internal flow field distribution is the prerequisite for keeping clean in the amplifier cavity. By means of computational fluid dynamics method and with the Fluent software, the internal flow field of slab amplifier cavity in the purging process of pure nitrogen is simulated, and the model validity is verified on the prototype system. By adjusting the structure and location arrangement of air inlets and outlets of the amplifier, the optimal flow field distribution is obtained. The experimental results show that compared with those of the non-optimized amplifier, the optimized amplifier not only takes only half time to obtain the same required cleanliness, but also the cleanliness of neodymium glass surface is higher..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 901002 (2016)
Measurement Technique of Signal Noise Ratio Based on Resonator Oscillation for Femtosecond Single-Shot Pulse
Shi Shuaixu, Yang Qingwei, Ouyang Xiaoping, Xia Suqiu, and Zhu Jianqiang
A measurement technique of signal noise ratio based on resonator oscillation for single-shot pulse is proposed. Through precise setting of the resonant cavity length, optical path difference between two resonant cavities, and the reflectivity or transmittance of the high reflectivity mirror, the three key indicators ofA measurement technique of signal noise ratio based on resonator oscillation for single-shot pulse is proposed. Through precise setting of the resonant cavity length, optical path difference between two resonant cavities, and the reflectivity or transmittance of the high reflectivity mirror, the three key indicators of high dynamic range, large time window and high temporal resolution are easily realized. Meanwhile, high fidelity of measurement signal is guaranteed using full aperture beam measurement. Theoretically, various kinds of function and stability of the resonator structure are analyzed. Influence of errors introduced by dispersion on results are also analyzed. High reflectivity mirrors with wedge-shape are introduced in the resonator cavity to avoid the noise of minor pulses. In theory, the measurement of high signal noise ratio (1010) ,even higher signal noise ratio, and high temporal resolution of hundred femtosecond can be realized in this construction..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 904001 (2016)
Comparison Among Different Interferometers for Measuring Power Spectral Density of Optical Elements
Yang Xianghui, Shen Weixing, Zhang Xuejie, and Ma Xiaojun
In order to investigate the response law of different interferometers to the mid-spatial frequency errors and obtain the relatively true power spectral density (PSD) distribution, the 4D AccuFiz, ZYGO DynaFiz and ZYGO GPI interferometers are respectively used to measure the periodic ripples and scratch samples, and theIn order to investigate the response law of different interferometers to the mid-spatial frequency errors and obtain the relatively true power spectral density (PSD) distribution, the 4D AccuFiz, ZYGO DynaFiz and ZYGO GPI interferometers are respectively used to measure the periodic ripples and scratch samples, and the comparative analysis of the measured one-dimension PSD curves is made. The results show that the responsivities to the mid- and high-spatial frequency information are different for different interferometers, and the higher the interferometer resolution is, the higher the responsivity is. The instrument transfer function (ITF) curve is used to correct the measured PSD, and the truer PSD distribution is obtained. However, in the range of some frequency bands, there still exist some difference between the ITF curve and the practical response..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 904002 (2016)
Online Detection of Airborne Molecular Contamination with Optical Microfiber and Quartz Crystal Microbalance
ZHU Zheng-hao, HAO Yan-fei, SUN Ming-ying, PANG Xiang-yang, LIU Zhi-gang, and ZHU Jian-qiang
In order to monitor the volatilization and deposition of organic contaminants on optics surfaces in high power laser facility, online detection of airborne molecular contaminant was investigated based on quartz crystal microbalance and optical microfiber. First, the response performance of quartz crystal microbalance fIn order to monitor the volatilization and deposition of organic contaminants on optics surfaces in high power laser facility, online detection of airborne molecular contaminant was investigated based on quartz crystal microbalance and optical microfiber. First, the response performance of quartz crystal microbalance for different densities of airborne molecular contamination was tested. Then the comparison of quartz crystal microbalance and optical microfiber in detecting the surface mass density of airborne molecular contamination was implemented with the view factor method. The characteristics of airborne molecular contamination deposited on optical surface were also studied. The experiment results show that quartz crystal microbalance and optical microfiber have the similar response performance, and thus they can be applied in online airborne molecular contamination detection. When the surface mass density of airborne molecular contamination is larger than 0.5×10－5g/cm2, optical microfiber is preferred due to the higher precision and larger response speed. The more the density of airborne molecular contamination is, the more it deposits on the optics..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 912008 (2016)
Fourth Harmonic Conversion of 1053 nm Laser Based on 65% Deuterated DKDP Crystals
Jiang Xiuqing, Ji Lailin, Liu Dong, Tang Shunxing, Guo Yajing, Zhu Baoqiang, and Lin Zunqi
Based on the mass fraction of 65% deuterated DKDP crystals, the fourth harmonic conversion of 1053 nm laser is realized under the condition of noncritical phase matching (NCPM). The experimentally measured crystal temperature is 29.4 ℃ and the acceptance angle width of the crystals under the NCPM condition is around 55Based on the mass fraction of 65% deuterated DKDP crystals, the fourth harmonic conversion of 1053 nm laser is realized under the condition of noncritical phase matching (NCPM). The experimentally measured crystal temperature is 29.4 ℃ and the acceptance angle width of the crystals under the NCPM condition is around 55 mrad. Effects of the deuterated amount and the temperature of the DKDP crystals in the process of NCPM on the fourth harmonic conversion are theoretically analyzed. The relationship between the deuterated amount and temperature and the changing of the fourth harmonic conversion efficiency versus the double frequency light intensity are numerically simulated. These results provide a theoretical basis for the application of fourth harmonic laser in the high power laser system..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 919002 (2016)
Development progress and performance test of optically addressed spatial light modulator
Huang Dajie, Fan Wei, Zhang Panzheng, Li Jinghui, Tang Shunxing, Guo Yajing, Li Xuechun, and Lin Zunqi
The development of the optically addressed spatial light modulator (OASLM) was reported. Its structure and working principle was introduced in detail. Meanwhile, the photosensitive response curve, static wave-front distortion and temporal waveform distortion was investigated in detail in the process of experiment. BesiThe development of the optically addressed spatial light modulator (OASLM) was reported. Its structure and working principle was introduced in detail. Meanwhile, the photosensitive response curve, static wave-front distortion and temporal waveform distortion was investigated in detail in the process of experiment. Besides, OASLM was successfully demonstrated in the online experiment. The results show that OASLM not only has the ability to achieve the desired transmittance distribution, but also has no additional effect on the high-power laser system. Finally, the shaping effect of spatial filter in the laser system was analyzed. The result shows that the size of spatial filter was also an important factor which determined the shaping precision when this device was used in high power laser systems..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 920001 (2016)
Arrangement of Beam-Guiding System in Target Areaof Laser Driver
Ren Lei, and Zhu Jianqiang
Beam-guiding system (BGS) has two functions, one shifts the array arrangement of the main laser to the spherical irradiation structure which meets the requirements of shooting laser, the other ensures that all the laser beams transmit to the target chamber center with the same light path length. Main issues are focusedBeam-guiding system (BGS) has two functions, one shifts the array arrangement of the main laser to the spherical irradiation structure which meets the requirements of shooting laser, the other ensures that all the laser beams transmit to the target chamber center with the same light path length. Main issues are focused on the transmission models of the main lasers and shooting lasers and the switch manner between them. Combining the symmetric properties of the beam port distribution on the target chamber, the transmission sub-unit is proposed to simplify the system arrangement. Firstly, considering the quantity and style of the total mirrors and the space size of the target area, the specific transmission models in a transmission sub-unit and the symmetrical division of target area are determined. Then, two possible transmission models for main lasers and shooting lasers are obtained with the constraints of laser polarization and no intersection among beams during propagation. The switch manner is calculated with a stratified baseline algorithm and the relationship between the image and object of the propagation lasers. In this manner, the entire BGS geometric arrangement is figured out..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 1101001 (2016)
Measurement of Thermal Distortion of the Optical Element in High Repetition Rate Laser with Coherent Modulation Imaging
Tao Hua, Liu Cheng, Pan Xingchen, Huang Wenfa, Huang Tingrui, and Zhu Jianqiang
When high-power solid laser working in high repetition rate, the laser output wave-front changes due to the thermal distortion, which is caused by the gain medium under the heat deposition. Therefore, the coherent modulation imaging technology is used to realize the measurement of the laser output wave-front from one fWhen high-power solid laser working in high repetition rate, the laser output wave-front changes due to the thermal distortion, which is caused by the gain medium under the heat deposition. Therefore, the coherent modulation imaging technology is used to realize the measurement of the laser output wave-front from one frame of diffraction intensity recorded. The phases of thermal distortion of the optical element are obtained when the amplifier working in 1, 5, 7 Hz frequency. Experimental results show that thermal distortion effect is significantly increased, the heat is concentrated toward the center region and the phase change increases as the working frequency increases..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 1101002 (2016)
Conceptual Design for Glass Cavity in Nd∶Glass Slab Amplifier
JIANG Meng-chun, ZHU Jian-qiang, LIU Zhi-gang, and WANG Li
To overcome the problem of cleanliness in the laser′s internal cavity, a glass cavity design for a Nd: glass slab amplifier was proposed, which uses UV-stop quartz glass for its main structure.The design of the main structure of the glass cavity and the sealing are optimized, and metal-coated surfaces are used to preveTo overcome the problem of cleanliness in the laser′s internal cavity, a glass cavity design for a Nd: glass slab amplifier was proposed, which uses UV-stop quartz glass for its main structure.The design of the main structure of the glass cavity and the sealing are optimized, and metal-coated surfaces are used to prevent light from escaping.The cleanliness of the stainless steel cavity of the slab amplifier of the SG-II-UP laser and the glass cavity of a 100 slab amplifier were compared; the cleanliness of the glass cavity was found to be 70% better than that of the stainless cavity. Further, advanced system analysis program was used to simulate the designed amplifier, with the pumping ratio of the Nd: glass in the glass cavity being increased by 8.84%.Thus, the glass cavity decreases the production of aerosols and enhances the pumping ratio of the Nd∶glass..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 1114001 (2016)
Single-Shot Isolation-Rate Measurement for Large-Aperture Faraday Rotator
Zhang Panzheng, Li Jinghui, Feng Tao, Wang Li, Zhang Zhixiang, Cao Zhaodong, Zhou Shenlei, Ma Weixin, and Zhu Jian
An all-fiber Faraday rotator isolation rate measurement system is designed and realized. The system has tremendous advantage for large aperture Faraday isolator on-line measurement due to its flexible alignment and more compaction. Employing the method of relative transmission measurement and transmissions contrasting An all-fiber Faraday rotator isolation rate measurement system is designed and realized. The system has tremendous advantage for large aperture Faraday isolator on-line measurement due to its flexible alignment and more compaction. Employing the method of relative transmission measurement and transmissions contrasting between static and operating states, single-shot isolation-rate measurement is achieved. The available measurement range larger than 33 dB is demonstrated experimentally. And the potential to get measurement range larger than 50 dB by adjusting the coupling rate of the fiber couplers is affirmed. Measurement accuracy of 2.2%of PV value is achieved even while keeping the input pulse energy and polarization in random vibration, which illustrates that the influence of the input pulse energy and polarization vibration on the measurement accuracy is eliminated..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 1204001 (2016)
Temperature-Insensitive Frequency Conversion by Electro-optic Effect Compensating for Phase Mismatch
Zijian Cui, Dean Liu, Aihua Yang, Jie Miao, Junyong Zhang, and Jianqiang Zhu
A universal phase mismatch compensation method, which can be applied to temperature-insensitive frequency conversion, is experimentally demonstrated. In this method, two nonlinear crystals and an electro-optic crystal are cascaded. The generated phase mismatch in the nonlinear crystal can be well compensated for in theA universal phase mismatch compensation method, which can be applied to temperature-insensitive frequency conversion, is experimentally demonstrated. In this method, two nonlinear crystals and an electro-optic crystal are cascaded. The generated phase mismatch in the nonlinear crystal can be well compensated for in the electro-optic crystal, thereby improving the stability of frequency conversion. In the proof-of-principle experiment, temperature-insensitive second and third harmonic generation (SHG and THG) are investigated by cascading KH2PO4 (KDP) and KD2PO4 (DKDP) crystals. The experimental results show that the temperature acceptance bandwidths of SHG and THG are 2.1 and 2.3 times larger, respectively, than that of the traditional method employing a single crystal. Meanwhile, the effectiveness of this method is also analyzed at a high power density, and a solution for the case of a nonuniform temperature is also discussed. Furthermore, angle-insensitive SHG is demonstrated to prove that this method can significantly reduce the influence of various unfavorable factors on frequency conversion. The demonstrated method may have potentially important applications in the nonlinear optical frequency conversion system..
Collection Of theses on high power laser and plasma physics
- Publication Date: Jan. 01, 1900
- Vol. 14, Issue 1, 6100308 (2016)
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