Journals >Chinese Journal of Lasers
Contents
2005
Volume: 32 Issue 3
30 Article(s)
Export citation format
Research Article
Misalignment Property Analysis of Corner Cube Reflector
[in Chinese], [in Chinese], and [in Chinese]
The reflection matrix of non-ideal corner cube is obtained by using the reflecting normal vector equation of rigid body with slight rotation. In order to find the effects of dihedral angle errors on the emerging beam, the equivalent principle of corner cube rotation around apex is used to calculate the angle δ between The reflection matrix of non-ideal corner cube is obtained by using the reflecting normal vector equation of rigid body with slight rotation. In order to find the effects of dihedral angle errors on the emerging beam, the equivalent principle of corner cube rotation around apex is used to calculate the angle δ between the incident beam and the emerging beam as a function of dihedral angle errors ε and rotation angle θ of corner cube. For an ideal corner cube, the emerging beam is parallel to the incident beam and two intersections that any plane through the apex cuts the two beams must be synmetrical about the apex. After corner cube randomly rotates around apex, the relations between the rotation angle and offset of emerging beam comparing with the original are investigated theoretically and experimentally. The results are in good agreement. The making, adjusting and testing of the corner cube reflector including the measurement and calculation of the dihedral angle errors are presented..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 306 (2005)
Athermalized Design of Extensive Temperature Range for Infrared Hybrid Refractive-Diffractive Objective
[in Chinese], [in Chinese], and [in Chinese]
For the requirement of extensive temperature adaptability of infrared optical systems, a refractive-diffractive hybrid approach is applied to an optical system with 114.7 mm focal length, F/1.5 F-number, ±2.5° field-of-view in the 3.2～4.2 μm waveband. The new designed hybrid system is passively athermalized oFor the requirement of extensive temperature adaptability of infrared optical systems, a refractive-diffractive hybrid approach is applied to an optical system with 114.7 mm focal length, F/1.5 F-number, ±2.5° field-of-view in the 3.2～4.2 μm waveband. The new designed hybrid system is passively athermalized over the temperature range from -60 ℃ to 160 ℃ with very high and stable imaging quality. The theoretical polychromatic modulation transfer function (MTF) is above 0.78 at space frequency of 20 lp/mm and is near to the diffraction-limitation. The lens is compatible with uncooled staring array imager with the picture element size over 25 μm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 311 (2005)
Optical Rotation of Crystal CaCO3 Micro-Particle in Optical Tweezers
[in Chinese], [in Chinese], and [in Chinese]
In the paper the principle of optical rotation due to the transfer of spin angular momentum from light to particles was discussed by analyzing the interaction between the beam of light and birefringent crystal particles, and then an optical tweezers was formed on nanometer optical tweezers system with a linearly polariIn the paper the principle of optical rotation due to the transfer of spin angular momentum from light to particles was discussed by analyzing the interaction between the beam of light and birefringent crystal particles, and then an optical tweezers was formed on nanometer optical tweezers system with a linearly polarized light beam (He-Ne laser 633 nm, 10 mW). A quarter wavelength plate was used to change the polarization of light. The calcite particles (about several μm in diameters) were then trapped by the optical tweezers under different polarization of light. At the same time optical rotation of the particles was realized. The rotation frequency was measured by CCD camera and quadrant photodiode detector (QD). The dependence of the rotation frequency of the trapped particle on the laser-power was analyzed and experimentally studied for several calcite crystallites with different sizes in the optical tweezers. The effects of several particle parameters such as thickness, radius, and orientation of its optic axis etc. were also discussed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 315 (2005)
Effect of the Polarization Direction of Incident Light on Electro-Optic Modulator for Light Propagating near the Optic Axis in LiNbO3
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The electro-optic effect in LiNbO3 crystal has been analyzed for light propagating near the optic axis with any polarization direction and for an electric field direction perpendicular to the optic axis. The passive and the electrically induced birefringences and the rotation of polarization direction have been calculaThe electro-optic effect in LiNbO3 crystal has been analyzed for light propagating near the optic axis with any polarization direction and for an electric field direction perpendicular to the optic axis. The passive and the electrically induced birefringences and the rotation of polarization direction have been calculated, and the conoscopic interference figures under orthogonal polariscopes for different polarization directions and a field in x-axis of LiNbO3 have been plotted. The extinction areas caused by the rotation of polarization direction change with the polarization direction of light, but the two heads of the induced optical axes do not vary, which are always on the induced principal axis with bigger refractive index. The directions of polariscopes are always extinction, and the ±45° directions with polariscopes always have the maximum intensity. The conoscopic interference figures have been demonstrated experimentally by rotating polariscopes directions, which are accord with the theoretically calculating plots..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 319 (2005)
Research of Optical Add-Drop Multiplexer Based on Mach-Zehnder Interferometer and Fiber Bragg Grating
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Optical add-drop multiplexer (OADM) is one of the key components for wavelength division multiplexing (WDM) system. A novel OADM based on Mach-Zehnder (M-Z) interferometer and fiber Bragg grating (FBG) is proposed. The OADM consists of two three-port optical circulators, a FBG, and a M-Z interferometer. In the structurOptical add-drop multiplexer (OADM) is one of the key components for wavelength division multiplexing (WDM) system. A novel OADM based on Mach-Zehnder (M-Z) interferometer and fiber Bragg grating (FBG) is proposed. The OADM consists of two three-port optical circulators, a FBG, and a M-Z interferometer. In the structure, the M-Z interferometer acts as an optical switch. The characteristic of the OADM is studied experimentally. In the experiment, the OADM can add/drop one of the multi input channel or pass the channel directly by adjusting the difference of the two arms of the interferometer. The channel isolation is more than 20 dB. The OADM has many advantages such as simple structure, small size, low cost and so on. It can be used in practical WDM system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 423 (2005)
Theoretical Analysis of Long-Period Moiré Gratings
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
As a kind of band-rejected loss filter, long-period fibre gratings have wide applications in the field of fibre communication and fibre sensing. Combined with the transmission characteristics of long-period fibre gratings, the transmission spectrums of various long-period moiré gratings were simulated by the methoAs a kind of band-rejected loss filter, long-period fibre gratings have wide applications in the field of fibre communication and fibre sensing. Combined with the transmission characteristics of long-period fibre gratings, the transmission spectrums of various long-period moiré gratings were simulated by the method of transfer Matrix. The results of analysis indicate that the moiré gratings technology can be well applied in fabricating the high-performance phase-shifted and apodised long-period fibre gratings..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 427 (2005)
Holography and Information Processing
An Image Fusion Approach Based on Object Region
[in Chinese], [in Chinese], and [in Chinese]
A novel approach using some information to define the regions of interest is proposed for combining multisensor images. Firstly, the original images are separated into object region and background region. Then based on using the à trous wavelet transform to decompose the original images, the fused coefficients areA novel approach using some information to define the regions of interest is proposed for combining multisensor images. Firstly, the original images are separated into object region and background region. Then based on using the à trous wavelet transform to decompose the original images, the fused coefficients are obtained by performing different fusion process to object region, background region and region boundaries between object region and background region. Finally, the fused image can be constructed by applying the inverse transformation. Experiments results show that the proposed approach outperforms the pixel-based and window-based image fusion methods..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 351 (2005)
Noises Mechanism of Range Image in Coherent Laser Radar and the Range Anomalies Suppression
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The noises mechanism of range image is analyzed in this paperThe noises mechanism of range image is analyzed in this paper.
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 356 (2005)
Experimental Study on High-Density Holographic Disk Storage with Batch Thermal Fixing
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Ten thousand images have been successfully stored in a single section of a disk-shaped, iron-doped LiNbO3 crystal using spatio-angular multiplexing with a convergent spherical reference beam, resulting in an areal density of 33.7 bits/μm2. On this basis, the batch thermal fixing technique was applied to holographic disTen thousand images have been successfully stored in a single section of a disk-shaped, iron-doped LiNbO3 crystal using spatio-angular multiplexing with a convergent spherical reference beam, resulting in an areal density of 33.7 bits/μm2. On this basis, the batch thermal fixing technique was applied to holographic disk storage. 5000 high-resolution images, divided in four batches, have been stored and fixed in the same crystal again but within a smaller area, resulting in a higher areal density of 50 bits/μm2. The application of convergent spherical reference beam and optimized optical set-up eliminated the detrimental scattering (from the crystal surface) and prevented it from entering the image detector. The images were reconstructed with good fidelity..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 361 (2005)
Laser Devices and Laser Physics
Research on Characteristics of Amplitude Modulation of a Reflective Liquid Crystal on Silicon Device
[in Chinese], [in Chinese], and [in Chinese]
The characteristics of amplitude modulation of a reflective liquid crystal on silicon (RLCOS) are discussed in this paper. The 2×2 Jones matrix methods is used to analyze amplitude modulation characteristics. The system is constructed for testing of amplitude and phase, in which He-Ne laser is used as the light soThe characteristics of amplitude modulation of a reflective liquid crystal on silicon (RLCOS) are discussed in this paper. The 2×2 Jones matrix methods is used to analyze amplitude modulation characteristics. The system is constructed for testing of amplitude and phase, in which He-Ne laser is used as the light source, the wave front amplitude is measured by the interferometer. The RLCOS display device as a mirror is used as a spatial light modulator and its driving circuit is controlled by a computer, digital data are sampled by CCD. The amplitude modulation characteristics of 1024×768 RLCOS display device are gotten. Comparing with the without sharped laser beam profile, the results show that under selected polarization states of input and output, RLCOS displays can be used as amplitude modulator..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 36 (2005)
Laser Manufacturing
Analysis of Temperature Field for Laser Assisted Mechanical Dressing and Truing of Diamond Grinding Wheel
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Laser assisted mechanical dressing and truing of diamond grinding wheel is a new truing and dressing method. The essential of the method lies in that laser irradiation makes deformation of diamond dresser material turn into ductile flow from brittle fracture, thereby improving the diamond wheel surface dressing and truLaser assisted mechanical dressing and truing of diamond grinding wheel is a new truing and dressing method. The essential of the method lies in that laser irradiation makes deformation of diamond dresser material turn into ductile flow from brittle fracture, thereby improving the diamond wheel surface dressing and truing quality and reducing the wear of diamond dresser. A simulation model established by finite element methods using ANSYS software showed the distribution temperature field inside the diamond wheel. The actual temperature field under experimental condition is measured by infrared thermal imager (Model NEC TH7100WX/WV). The analyses show that the theoretical calculation results are consistent with those of experiments in the same experiment condition. The simulation model provides good effects on the quality forecast, parameter regulation and optimization in the process of truing and dressing diamond wheel. It also helps to avoid that high temperature make diamond grain graphitization or the temperature is not high enough to soften diamond wheel. The simulation model reduces the blindness to true and dress diamond wheel directly..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 431 (2005)
Study on Microstructure of SiCp/Al Composite Materials by CO2 Laser Cladding/Injection
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
SiC/Al composite coating has been produced by laser particle cladding/injection. Materials used are as followsSiC/Al composite coating has been produced by laser particle cladding/injection. Materials used are as follows.
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 436 (2005)
Laser Physics
Study of High Power Laser Diode End-Pumped Composite Crystal Lasers
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Effect of thermal lensing is the main obstacle of getting high power and good beam quality in laser diode (LD)-pumped solid-state lasers. A theoretical investigation of effects of thermal lensing in an end-pumped Nd∶YVO4 laser is demonstrated using finite-element-method, showing that the thermal lensing effect in high Effect of thermal lensing is the main obstacle of getting high power and good beam quality in laser diode (LD)-pumped solid-state lasers. A theoretical investigation of effects of thermal lensing in an end-pumped Nd∶YVO4 laser is demonstrated using finite-element-method, showing that the thermal lensing effect in high power LD-pumped Nd∶YVO4 lasers is very serious, particularly the end deformation which accounts for 50% of the overall thermal lensing effect. The employment of a composite crystal has been demonstrated to be a useful method in relieving the thermal lensing, resulting in higher output power and better beam quality. The fundamental mode output power as high as 11 W has been achieved with 23 W pump power in composite crystal, the beam quality factor M2 is less than 1.5, and O-O conversion efficiency is up to 48%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 297 (2005)
Design and Manufacture for Select Frequency Oscillation Grating in the Zero-Order Coupling Output of 9.77 μm Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The physical model of real ruled grating is proposed, the corresponding expression of diffraction efficiency is given, and design principle of blazed grating for frequency-selection oscillation in zero-order output for an infrared (IR) laser is introduced. On the base of the result of theory analysis, the technologies The physical model of real ruled grating is proposed, the corresponding expression of diffraction efficiency is given, and design principle of blazed grating for frequency-selection oscillation in zero-order output for an infrared (IR) laser is introduced. On the base of the result of theory analysis, the technologies are adopted that adjusting the ruled load to control the zero-order plane of the grating and bi-directionally gradually approach the design value of the diffraction efficiencies of the zero-order and first-order, the gilt blazed grating is made with the first-order diffraction efficiency of 86.5% and the zero-order diffraction efficiency of 10.3% in Littrow form. The testing result shows that the deviations of the zero-order and first-order diffraction efficiency from the designed central value are only 0.6% and 3%, respectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 301 (2005)
Evolution of Bright-Dark Vector Spatial Solitons in Biased Photorefractive-Photovoltaic Crystals
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The bright-dark vector spatial solitons are predicted in biased photorefractive-photovoltaic crystals, which result from both the bulk photovoltaic effect and the spatially nonuniform screening of the external bias field. When the bulk photorefractive effect can be neglected, the physical system of these bright-dark veThe bright-dark vector spatial solitons are predicted in biased photorefractive-photovoltaic crystals, which result from both the bulk photovoltaic effect and the spatially nonuniform screening of the external bias field. When the bulk photorefractive effect can be neglected, the physical system of these bright-dark vector solitons changes into that of bright-dark vector screening solitons, and these bright-dark vector solitons change into bright-dark vector screening solitons. When the external field is absent, the physical system of these bright-dark vector solitons predicts that of bright-dark vector photovoltaic solitons, and these bright-dark vector solitons predict bright-dark vector photovoltaic solitons. The stability of these bright-dark vector solitons is discussed using a beam propagation method. When σ>0 and (β+α-δ)>0, where σ is the parameter controlling the intensities of the two optical beams, α and δ are the parameters related to the photovoltaic constant, and β is the parameter related to external electric field, these bright-dark vector solitons are stable in the regime of (β+α-δ) being less than a certain value. When σ<0 and (β+α-δ)<0, these bright-dark vector solitons are also stable in the regime of (β+α-δ) being greater than a certain value..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 323 (2005)
Flatting of Temperature Distribution in Laser Induced Diffusion Region
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In the fabrication of photodiode of monolithic integrated photoreceiver using laser induced diffusion, because the high temperature region is very small, when the intensity distribution of incident laser beam is Gaussian or uniform, the uniformity of the temperature distribution in the diffusion region cannot meet the In the fabrication of photodiode of monolithic integrated photoreceiver using laser induced diffusion, because the high temperature region is very small, when the intensity distribution of incident laser beam is Gaussian or uniform, the uniformity of the temperature distribution in the diffusion region cannot meet the requirement of uniformity. In this paper, a method to homogenize the temperature through modulating of the intensity incident on the surface using a mask is proposed. The key of this method is calculating the laser intensity distribution, which can induce uniform temperature rise in the diffusion region. The numerical method to solve this problem is described. The results show that when the mean temperature rise in the diffusion region is about 500 K, the maximum temperature difference of 3.9 K can be achieved, and the temperature distribution approaches “flatcap”..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 327 (2005)
Experimental and Theoretical Study of the Oscillation of a Laser-Induced Bubble
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
By means of a high-sensitive fiber-optic sensor based on optical beam deflection, the oscillating property of a laser-induced cavitation bubble in the vicinity of an aluminum target in water is investigated in detail. The characteristic waveforms induced by a cavity during the two oscillating cycles are presented and tBy means of a high-sensitive fiber-optic sensor based on optical beam deflection, the oscillating property of a laser-induced cavitation bubble in the vicinity of an aluminum target in water is investigated in detail. The characteristic waveforms induced by a cavity during the two oscillating cycles are presented and the corresponding maximum and minimum radii are determined. Furthermore, the variations of the gas content in a cavity at each oscillation are estimated according to the bubble-collapsing theory. The experimental results are shown that the less the remained gas in a cavity, the more violent the cavity contracts, the smaller the corresponding minimum bubble radii and the shorter the oscillating durations are..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 331 (2005)
Grating Signal Quality Assessment Based on Wavelet Analysis
[in Chinese], [in Chinese], and [in Chinese]
On the basis of the signal quality standard given by the harmonic analysis method, an quality assessment of grating signal based on wavelet analysis is put forward and its characteristics are discussed. Compared with the harmonic analysis method, wavelet analysis characterize its local excellence both in time and frequOn the basis of the signal quality standard given by the harmonic analysis method, an quality assessment of grating signal based on wavelet analysis is put forward and its characteristics are discussed. Compared with the harmonic analysis method, wavelet analysis characterize its local excellence both in time and frequency domain for every time of the wavelet transformation, with the wavelet analysis method the transient characteristic of the grating signal can be analyzed more subtly by changing the scale, and all possible noise can be filtered. The most possible approximation of the original signal and the least signal distortion are get with three to five times transformation, the ideal result is then quickly obtained. The corresponding experiment of grating signal quality assessment is given with wavelet analysis..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 336 (2005)
Materials and Thin Films
Thermal, Spectra and Laser Properties of Yb∶Zinc-Germanium-Tellurite Glasses for Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A series of new multi-component glasses of 0.70TeO2-(0.20-x)ZnO-xGeO2-0.05La2O3-0.025K2O-0.025Na2O-0.01Yb2O3 (mole fraction x=0, 0.05, 0.10, 0.15, 0.20) were presented. Thermal stability of the system, spectra and laser properties of Yb3+ ions were measured. The result shows that the composition glass of x=0.20 has gooA series of new multi-component glasses of 0.70TeO2-(0.20-x)ZnO-xGeO2-0.05La2O3-0.025K2O-0.025Na2O-0.01Yb2O3 (mole fraction x=0, 0.05, 0.10, 0.15, 0.20) were presented. Thermal stability of the system, spectra and laser properties of Yb3+ ions were measured. The result shows that the composition glass of x=0.20 has good thermal stability, large stimulated emission cross-section of 1.23 pm2 for the 2F5/2→2F7/2 transition, longer fluorescence lifetime of 0.92 ms, broad fluorescence effective linewidth of 77 nm and minimize pump intensity of 0.98 kW/cm2. Evaluated from the good potential laser parameters, it is desirable for high-average power and short pulse tunable laser..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 365 (2005)
One-Dimensional Spatial Distribution of Photo-Induced Birefringence of Azobenzene Dye-Doped Polymers
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Experimental investigation of one-dimensional spatial distribution of photo-induced birefringence of azobenzene dye-doped polymers is reported. The orientational motion of chromophores and the consequential inter-molecular motion of the surrounding area are confirmed based on the spatial distribution and its evolution.Experimental investigation of one-dimensional spatial distribution of photo-induced birefringence of azobenzene dye-doped polymers is reported. The orientational motion of chromophores and the consequential inter-molecular motion of the surrounding area are confirmed based on the spatial distribution and its evolution. It is found that orientational motion of chromophores and the consequential inter-molecular motion are dependent on the pump power and the size of the chromophores by the qualitative investigation of three kinds of azobenzene dye DR1, DR13 and DY7 doped PMMA polymers..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 370 (2005)
Properties of Er3+/Yb3+ Codoped Phosphate Glass for Waveguide Amplifiers
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel Er3+/Yb3+ codoped phosphate glass WM4 was designed and developed, which exhibited good chemical durability in molten salts and good spectroscopic properties. The stimulated emission cross-section of 4I13/2→4I15/2 transition of Er3+ ions and Judd-Ofelt intensity parameters Ωt (t=2,4,6) were obtained by analyzingA novel Er3+/Yb3+ codoped phosphate glass WM4 was designed and developed, which exhibited good chemical durability in molten salts and good spectroscopic properties. The stimulated emission cross-section of 4I13/2→4I15/2 transition of Er3+ ions and Judd-Ofelt intensity parameters Ωt (t=2,4,6) were obtained by analyzing the room temperature absorption spectrum; the stimulated emission cross-section of 4I13/2→4I15/2 transition of Er3+ ions was 0.72×10-20 cm2, which is larger than that of Schott′s IOG1, 0.67×10-20 cm2. Preliminary results of ion exchange at different time and temperature with varying molten salt compositions indicated that WM4 glass was suitable for ion exchange process and Er3+-doped waveguide amplifier (EDWA) application, and single mode optical waveguide at 1.55 μm was fabricated. The propagation loss of all the waveguides was less than 1 dB/cm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 375 (2005)
Thermal Distortion Measurements and Absorption Analysis by Finite Element Method of High Power DF Laser Reflectors
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Irradiated by a continuous wave (CW) DF laser with power of ～30 kW, wavelength of 3.8 μm, and irradiation time of 1 s, under the conditions of the laser beam approximately perpendicular to the coaxially rounded reflector, the thermal distortions of 3.8/0.633 μm dual-wavebands multi-layer high-power laser reflectors manIrradiated by a continuous wave (CW) DF laser with power of ～30 kW, wavelength of 3.8 μm, and irradiation time of 1 s, under the conditions of the laser beam approximately perpendicular to the coaxially rounded reflector, the thermal distortions of 3.8/0.633 μm dual-wavebands multi-layer high-power laser reflectors manufactured by different crafts are tested by a Shack-Hartmann wave-front sensor. Based on the thermal conduction equations and thermal-elastic equations, taken account of the thermal effect of the refractivity of the air, a finite element method is used to estimate the thermal absorptions of the reflectors. The results indicate that the lowest thermal absorpaility of the reflectors manufactured with best crafts is approached to 80×10-6. On account of the materials and the structure designs of the coatings being all complete the same, the purpose of the film-plating parameters estimate and/or evaluating is realized..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 379 (2005)
Laser-Induced Damage of Ta2O5/SiO2 Two-Cavity Narrow-Band Interference Filters
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The laser-induce damage threshold (LIDT) of Ta2O5/SiO2 two-cavity narrow-band interference filters with different central wavelength was investigated with a Nd∶YAG laser at 1064 nm under single-pulse mode, and the absorption measurement of such coatings was also performed by surface thermal lensing (STL) technique. It The laser-induce damage threshold (LIDT) of Ta2O5/SiO2 two-cavity narrow-band interference filters with different central wavelength was investigated with a Nd∶YAG laser at 1064 nm under single-pulse mode, and the absorption measurement of such coatings was also performed by surface thermal lensing (STL) technique. It is found that the narrow-band interference filters showed different laser-induced damage behavior in the different zone (interband, band edge and rejection zone) of such coatings under high power laser irradiation. Using the electric distribution theoretical calculating, the experimental results have been analyzed in detail. The laser-induced damage behavior of such filters are in agreement with theoretical prediction..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 384 (2005)
Measurement and Metrology
Method of Heterodyne Confocal Microscopy Measuring Big Step Height
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Step height is an important parameter of micro-electronic mask. A new approach named dual-frequency interferometric confocal microscope (DICM) is proposed which combines scanning confocal microscopy with heterodyne interferometry. The phase of heterodyne interferometry is recorded as an aim criteria when optical intensStep height is an important parameter of micro-electronic mask. A new approach named dual-frequency interferometric confocal microscope (DICM) is proposed which combines scanning confocal microscopy with heterodyne interferometry. The phase of heterodyne interferometry is recorded as an aim criteria when optical intensity of confocal microscopy is in maximum. This method implements high resolution (0.1 nm) and relatively large measurement range (>15 μm) simultaneously. Also the step height measurement range depending on the range of Z axis PI-Foc scanner which theoretically can be extended to 100 μm. The results show that in ordinary laboratory condition, with temperature controlled , the drift of phase measurement is about 5 nm in an hour. The 20 μm step height has been successfully measured and the results agree with the actual value..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 389 (2005)
Micro-Displacement Measurement Based on Grating Projection
[in Chinese], and [in Chinese]
A method to measure micro-displacements based on grating projection is proposed and analyzed theoretically. A grating is illuminated by a collimated laser beam and projected onto an object to be measured through a 4f optical system with an aperture in its frequency plane. The grating projection is imaged on a detectionA method to measure micro-displacements based on grating projection is proposed and analyzed theoretically. A grating is illuminated by a collimated laser beam and projected onto an object to be measured through a 4f optical system with an aperture in its frequency plane. The grating projection is imaged on a detection grating through another 4f optical system after reflected by the surface of the object. The detection grating is imaged on a detector and its imaging beam is modulated by a photoelastic modulator. The micro-displacement of the object is obtained by detecting the light intensity on detector. In experiments, the feasibility is verified and the repeatability of the method is less than 25 nm (1σ)..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 394 (2005)
Integrated Optics Michelson Interference Acceleration Seismic Geophone
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
For high resolution application in seismic detection, the geophone should be small in size, reliable and sensitive. An integrated optic Michelson interference acceleration seismic geophone has been studied and fabricated. The device is realized by an light source, a photodetector, and Michelson interference integrated For high resolution application in seismic detection, the geophone should be small in size, reliable and sensitive. An integrated optic Michelson interference acceleration seismic geophone has been studied and fabricated. The device is realized by an light source, a photodetector, and Michelson interference integrated optical chips, which are hybrid integrated. The main design parameters of the geophone system are as following.
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 399 (2005)
Measurement of the Homogeneity of Refractive Index of the Germanium Crystal Using IR Interferometer
[in Chinese], [in Chinese], and [in Chinese]
The method is presented to measure the homogeneity of the refractive index of infrared optical material, germanium crystal, using infrared interferometer with 10.6 μm wavelength laser as light source. Using traditional interferometric method, as the germanium material is too soft to process, the surface form of the tesThe method is presented to measure the homogeneity of the refractive index of infrared optical material, germanium crystal, using infrared interferometer with 10.6 μm wavelength laser as light source. Using traditional interferometric method, as the germanium material is too soft to process, the surface form of the test piece may not meet the requirement for the measurement. The digital phase-shifting interferometer with visible light source is an accurate instrument of which uncertainty is within λ/50 (λ=0.633 μm). The surface distributions of test piece are accurately obtained using the phase-shifting interferometer with visual light source and surface errors are subtracted during the data processing to reduce the affection from the surface form deviation during the interference test. A piece of germanium crystal is tested and the deviation distribution of the refractive index is presented..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 404 (2005)
Research of Pulse Injection Method for Measuring LD Chip Temperature
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An accurate method for measuring the chip temperature of semiconductor lasers is presented. Because the heat capacity of semiconductor laser is very small, using pulse injection can reduce temperature rising significantly. First, the change of environment temperature versus lasing wavelength under pulse injection is diAn accurate method for measuring the chip temperature of semiconductor lasers is presented. Because the heat capacity of semiconductor laser is very small, using pulse injection can reduce temperature rising significantly. First, the change of environment temperature versus lasing wavelength under pulse injection is discussed, and the relationship between the lasing wavelength and the width and cycle of injection pulse is obtained. The measured relationship agrees well with the calculated one. Based on this relationship the optimum parameters of the pulse for measuring the chip temperature of laser diode (LD) are obtained, viz. pulse width is 10 ns, pulse cycle is 10 μs. The definite relation between lasing wavelength and chip temperature is developed, and the drift coefficient is 0.0728 nm/K. This method avoids junction voltage overshoot in electricity measurement, and it is more accurate than the latter. This method is also convenient for measuring temperature character of packaged laser unit..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 407 (2005)
Optical Communication
Research on Suppressing Soliton Interaction Using Phase-Sensitive Amplifiers
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Using phase-sensitive amplifiers (PSA) as in-line amplifiers to suppress soliton interaction in soliton transmission system was theoretically analyzed by computer simulation. For comparison, the interaction of soliton in the system using erbium-doped fiber amplifiers (EDFA) as in-line amplifiers was also simulated. TheUsing phase-sensitive amplifiers (PSA) as in-line amplifiers to suppress soliton interaction in soliton transmission system was theoretically analyzed by computer simulation. For comparison, the interaction of soliton in the system using erbium-doped fiber amplifiers (EDFA) as in-line amplifiers was also simulated. The simulation considered both average-soliton regime and dynamic-soliton regime. The results show that using PSAs instead of EDFAs as in-line amplifiers can effectively suppress the pulse broadening and soliton interaction. For average-soliton, without additional control techniques, the interaction between solitons can be suppressed and the steady transmission distance can be lengthened greatly. For dynamic-soliton system, PSA also has a good behavior of suppressing soliton interaction. But after long distance transmission, the amplitude of soliton pulse descends significantly..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 411 (2005)
Analysis of the Characteristics of the All-Optical Switch Based on Nonlinear Amplifying Loop Mirror
[in Chinese], and [in Chinese]
A kind of all-optical switch, which is constructed by a nonlinear amplifying loop mirror (NALM) based on erbium-doped fiber amplifier (EDFA) and high nonlinear dispersion shifted fiber (HNL-DSF), is presented. With the high gain coefficient of EDFA and the optical Kerr effect of HNL-DSF, this configuration can be used A kind of all-optical switch, which is constructed by a nonlinear amplifying loop mirror (NALM) based on erbium-doped fiber amplifier (EDFA) and high nonlinear dispersion shifted fiber (HNL-DSF), is presented. With the high gain coefficient of EDFA and the optical Kerr effect of HNL-DSF, this configuration can be used to shape the optical pulse and suppress the pedestal and noise. The effect of group velocity dispersion (GVD) of HNL-DSF on the switch characteristics of NALM is analyzed by split-step Fourier method. Meanwhile, the effects of the gain coefficient, the saturation of EDFA and the coupling ratio of optical coupler are discussed theoretically and numerically. NALM has intensity-dependent filtering character and the input power required to obtain nonlinear input-output relationship reduces to a low level. Through optimizing every parameter, a switching operation over 1 Tbit/s can be realized on the short pulse and the threshold value of the switch can be lower than 1 mW..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 3, 418 (2005)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20