Contents
2006
Volume: 26 Issue 7
32 Article(s)
Export citation format
Atmospheric Optics and Oceanic Optics
Determination of Aerosol Optical Thickness and Atmospheric Visibility by Differential Optical Absorption Spectroscopy
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
With the method of differential optical absorption spectroscopy (DOAS), aerosol along the light path is measured with a flashlight source. After calibrating the system parameters by the visibility in the clear day, the difficulty to measure the original light intensity in aerosel measurement with DOAS is resolved, and With the method of differential optical absorption spectroscopy (DOAS), aerosol along the light path is measured with a flashlight source. After calibrating the system parameters by the visibility in the clear day, the difficulty to measure the original light intensity in aerosel measurement with DOAS is resolved, and the optical thickness from 350～650 nm is obtained with method of inversion. Comparison with solar photometer and good correlation is found between aerosol optical thickness and suspended particle matter concentration. In addition, the atmospheric visibility is retrieved by extinction coefficient at 550 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 961 (2006)
Study on Modulation Property of Broadband Laser Propagation in Free Space
[in Chinese], [in Chinese], and [in Chinese]
The free space propagation property of broadband laser beam in Fresnel diffraction area is studied based on Huygens-Fresnel diffraction integral. The relationship between modulation depth, bandwidth Δλ and Fresnel number is obtained. It is found that the uniformity of the beam is improved to a certain extent for an appThe free space propagation property of broadband laser beam in Fresnel diffraction area is studied based on Huygens-Fresnel diffraction integral. The relationship between modulation depth, bandwidth Δλ and Fresnel number is obtained. It is found that the uniformity of the beam is improved to a certain extent for an appropriate bandwidth. The bandwidth is widened, and the beam is more uniform, for Δλ > 2λ0/F. Fresnel diffraction disappears completely when Δλ = 2λ0/F is fulfilled. For Fresnel number in a certain range, the modulation depth of broadband laser beam oscillates with the Fresnel number, with the main and secondary maximums of the oscillating curve appearing for odd and even Fresnel number respectively. Its minimums exist for Fresnel number F=2k±1/3 (k=1, 2, 3 …), and meanwhile the uniformity of the laser beam is the best..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 965 (2006)
The Starlight Refraction in Autonomous Orbit Determination for Satellite By Large Field of View Star Sensors
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
By supposing the atmosphere is of spherical symmetry,starlight refraction model is given deriving from atmospheric refractive index, refractive path in atmosphere and Snell law for the observing method by large field of view star sensors in autonomous orbit determination. On the assumption that the starlight refractionBy supposing the atmosphere is of spherical symmetry,starlight refraction model is given deriving from atmospheric refractive index, refractive path in atmosphere and Snell law for the observing method by large field of view star sensors in autonomous orbit determination. On the assumption that the starlight refraction does not happen on the spherical surface whose altitude is larger than 60 km, the relations among the elevation angle θ60 of starlight on atmospheric altitude of 60 km, the starlight refraction angle γ and the starlight tangent altitude h are obtained. And the result shows that range of change of θ60 is from 0°to 7°. At last, the orbit determination simulation is done using this refraction model, and the validity of the model is shown..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 26, Issue 7, 972 (2006)
Design Principle of Performance Testing Device for Laser Beam Microradian Pointing and Tracking in Intersatellite Laser Communications
[in Chinese], [in Chinese], and [in Chinese]
Starting from vector refraction theorem, the design principle of transmitted laser beam through double-prism to perform microradian deviation is researched, and the testing problem of fine pointing and tracking in inter-satellite optical communications is solved. The accurate formula for laser beam deviation through a Starting from vector refraction theorem, the design principle of transmitted laser beam through double-prism to perform microradian deviation is researched, and the testing problem of fine pointing and tracking in inter-satellite optical communications is solved. The accurate formula for laser beam deviation through a pair of orthogonal prisms is derived, the visual field defined as level field angle and vertical field angle is proposed, and the general situation of laser beam deviation through single prism is also presented. The main parameters of prisms, according to design object and calculation result, are confirmed, and then the numerical simulation on the deviation result of laser beam is carried out. The final results from the tests accord well with those from the theoretical analysis. The results show, when the prism wedge angle is 4°, the transmitted laser beam changes about 1 μrad as the prism rotates 1′; when the small angle deviation on one side of the minimum deviation angle of each prism is controlled, the scanning range of laser beam in the horizontal and vertical direction is not less than 500 μrad, and the scanning precision of the device is superior to 0.2 μrad..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 975 (2006)
Diffraction and Gratings
Diffraction Properties of Reflection Volume Holographic Grating Illuminated by an Ultrashort Pulsed Laser Beam
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Considering the dispersion effect of the grating media, the coupled wave theory of Kogelnik is developed to study the diffraction properties of an ultra-short pulsed laser beam with different polarizated states, vertical or parallel to the incident plane by a reflection volume holographic grating. A special case of graConsidering the dispersion effect of the grating media, the coupled wave theory of Kogelnik is developed to study the diffraction properties of an ultra-short pulsed laser beam with different polarizated states, vertical or parallel to the incident plane by a reflection volume holographic grating. A special case of grating which is recorded in anisotropic photorefractive LiNbO3 crystals is given. It is investigated that the spectral bandwidth of the grating for the ultra-short pulsed laser beam with perpendicularly polarizated state is larger than that with parallel polarizated state, and both of them are reduced by the dispersion effect of the grating media. The spectral bandwidth variation of the diffraction light, and the diffraction efficiency variation of the volume holographic grating are studied with the spectral width ratio of the incident pulse and the grating..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 980 (2006)
Theoretical Study of Recording Varied Line Spacing Plane Holographic Gratings by Using Auxiliary Gratings
[in Chinese], [in Chinese], and [in Chinese]
Due to the ability of self-focusing and aberration-eliminating, varied line spacing holographic gratings have been the significant elements in high-resolution spectrometers and synchrotron radiation monochromators. Uniform line spacing plane gratings are introduced into recording systems to generate aspheric wavefrontsDue to the ability of self-focusing and aberration-eliminating, varied line spacing holographic gratings have been the significant elements in high-resolution spectrometers and synchrotron radiation monochromators. Uniform line spacing plane gratings are introduced into recording systems to generate aspheric wavefronts to record varied line spacing plane holographic gratings. Analytical expressions of groove parameters are derived up to the forth order with ray-tracing theory of geometry optics. A numerical ray-tracing algorithm is provided based on Fermat's principle. A varied line spacing holographic grating is designed by applying the derived forth order expressions of grating parameters. Other diffractive light will not disturb the recording process when the recording parameters are properly selected. According to the design example, theoretical groove density parameters are very close to the required value. The truncation error of series expansion is less than 1.5 lines in the recording area through the validation of numerical ray-tracing algorithm. Considering the tolerances in practical fabrication, this mounting is not sensitive to the errors of recording parameters. Design results demonstrate the exactness of analytical expressions, and the superiority of recording optics with auxiliary gratings..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 985 (2006)
Fiber Optics and Optical Communications
A Novel Method for Reconstructing Strongly Reflecting Fiber Bragg Gratings
[in Chinese], [in Chinese], and [in Chinese]
The theory of fiber Bragg grating (FBG) reconstruction and the widely used layer-peeling (LP) algorithm are illustrated. The deficiency of LP algorithm in reconstructing strongly reflecting FBGs is pointed out and a hybrid method of combining genetic algorithm with LP algorithm is proposed. In this method, the preliminThe theory of fiber Bragg grating (FBG) reconstruction and the widely used layer-peeling (LP) algorithm are illustrated. The deficiency of LP algorithm in reconstructing strongly reflecting FBGs is pointed out and a hybrid method of combining genetic algorithm with LP algorithm is proposed. In this method, the preliminary values of the grating couple coefficients are obtained by using LP algorithm, and then genetic algorithm is employed to optimize the latter half of the results of the LP algorithm according to the re-sampled preliminary value with which the starting population of genetic algorithm are created. By numerical simulation, the novel method is proved to be fast convergent, very accurate, suitable for reconstructing most of strongly reflecting FBGs, and improve the result of LP algorithm effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 991 (2006)
Demodulation Algorithm for Frequency-Division-Multiplexed Fiber-Optic Fizeau Strain Sensor Networks
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A spectral demodulation algorithm based on Pisarenko sine wave recovery method for frequency-division-multiplexed (FDM) fiber-optic Fizeau strain sensor networks is proposed, which is used to effectively reduce the cross talk between two adjacent sensors, and thus enhance the network multiplexing capability. Based on pA spectral demodulation algorithm based on Pisarenko sine wave recovery method for frequency-division-multiplexed (FDM) fiber-optic Fizeau strain sensor networks is proposed, which is used to effectively reduce the cross talk between two adjacent sensors, and thus enhance the network multiplexing capability. Based on principle of multi-beam interferomety, demodulation model for such networks is built up and experiments are carried out to study the cross talk of two fiber-optic Fizeau sensors. The experimental results show that a strain accuracy better than ±10 με has been achieved even when the cavity length difference is 100 μm approximately, while it is about 500 μm for fast Fourier transform. It demonstrates that the multiplexing capability of the FDM fiber-optic Fizeau sensor networks can be improved by 5 times. Hence, with a low cross talk and strong multiplexing capality, the method can be widely used in quasi-distributed high multiplexing capability optical sensing systems..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 997 (2006)
Four-Core Fiber Based Bending Sensor
[in Chinese], [in Chinese], and [in Chinese]
A novel four-core fiber-based bending sensor has been proposed, in which four-core fiber is used as the sensing element, the four cores of the fiber act as a four-beam interferometer, and the far-field interferogram grids with periodical distributions are formed on the fiber output end. The phase difference is a functiA novel four-core fiber-based bending sensor has been proposed, in which four-core fiber is used as the sensing element, the four cores of the fiber act as a four-beam interferometer, and the far-field interferogram grids with periodical distributions are formed on the fiber output end. The phase difference is a function of the radius of curvature, so the change of the radius of curvature shifts the far-field interferometric grid pattern. A low-coherence laser diode with wavelength of 650 nm is adopted to illuminate the fiber and the interferogram pattern in the far-field is recorded by a CCD camera. The relationship between the far-field grid pattern intensity distribution and the radius of curvature is established theoretically and confirmed experimentally..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1001 (2006)
Analysis of the Transmission Spectral Characteristics of Fiber Bragg Grating in Photonic Crystal Fibers
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
It is essential for the development of photonic crystal fiber based fiber grating devices to study the transmission spectral characteristics of the fiber grating in photonic crystal fiber. Based on the coupled mode theory and beam propagation correlation function mode-solver, the transmission spectrum of a typical fibeIt is essential for the development of photonic crystal fiber based fiber grating devices to study the transmission spectral characteristics of the fiber grating in photonic crystal fiber. Based on the coupled mode theory and beam propagation correlation function mode-solver, the transmission spectrum of a typical fiber Bragg grating in photonic crystal fiber is studied. The transmission spectra of fiber Bragg grating in photonic crystal fiber and conventional fiber are compared. The influence of the structure change of the fiber cross section on the transmission spectrum is simulated, and derived qualitatively. It is found that the loss peaks caused by cladding mode resonances have similar strengths with those caused by the bidirectional core mode coupling, and the spacing of cladding mode resonances is larger than that in a conventional fiber. Meanwhile, the rule of effects of duty ratio of the air holes and the layer number of the air holes on the transmission spectrum is given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1007 (2006)
Refractive Index Sensing Characteristics of Fiber Bragg Grating Based on Cladding Mod
[in Chinese], [in Chinese], and [in Chinese]
A new refractive index sensing scheme based on the cladding modes of fiber Bragg grating (FBG) is presented. In the experiments, glycerin aquatic solutions with different concertrations are used as the external refractive index sensing media, and the cladding diameter of FBG is reduced by etching the fiber with HF soluA new refractive index sensing scheme based on the cladding modes of fiber Bragg grating (FBG) is presented. In the experiments, glycerin aquatic solutions with different concertrations are used as the external refractive index sensing media, and the cladding diameter of FBG is reduced by etching the fiber with HF solution to enhance the sensitivity of cladding modes to the external refractive index. Dependence of the coupling wavelength of the etched FBG cladding mode on the external refractive index is measured. The results show that in the refractive index range of 1.3300～1.4584, the coupling wavelength of cladding mode shifts longer with the increase of the external refractive index and a higher sensitivity is achieved when the external refractive index is close to that of fiber cladding's, and the maximum refractive index sensitivity reaches 172 nm/riu (refractive index unit). Furthermore, the full-width-at-half-maximum (FWHM) of resonant cladding mode is 0.07 nm, which is about 1/4 of that of the core mode's. With this narrower spectrum, a higher sensing resolution can be achieved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1013 (2006)
Imaging Systems
A Study of Automatic Extraction Method of Defects on X Image
[in Chinese], and [in Chinese]
Defect extraction techniques are studied regarding the characteristic of X-ray images of carbon product, and threshold-construction method based on iteration and edge-extraction algorithm based on mathematical morphology are advanced. In order to extract defects quickly and exactly, target boundary extraction algorithmDefect extraction techniques are studied regarding the characteristic of X-ray images of carbon product, and threshold-construction method based on iteration and edge-extraction algorithm based on mathematical morphology are advanced. In order to extract defects quickly and exactly, target boundary extraction algorithm and image enhancement algorithm based on wavelet transform are proposed, background removal and enhancement of object region are implemented successfully. Based on this method, combining mathematical morphology and iteration threshold segmentation is adopted to extract defect in order to eliminate the noise disturbance, and with iteration threshold segmentation, defect edge-extraction is realized based on edge-extraction algorithm of mathematical morphology. The experimental results indicate that the method can achieve automatic extraction of defect region and edge with weak noise disturbance , which lays a good foundation for flaw feature parameter extraction and choice..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1016 (2006)
Effect of Distance on Modulation Transfer Function of Imaging Sensor Using Rectangle Template Contact Method
[in Chinese], [in Chinese], and [in Chinese]
In order to measure the modulation transfer function of the imaging sensor simply and expediently, the method with the template directly projecting on the imaging sensor has been adopted. Usually, the rectangle template is adopted, and there is a distance between the template and the photosensitive surface, which is crIn order to measure the modulation transfer function of the imaging sensor simply and expediently, the method with the template directly projecting on the imaging sensor has been adopted. Usually, the rectangle template is adopted, and there is a distance between the template and the photosensitive surface, which is critical in the measurement. The optical distribution on the rectangle template and the photosensitive surface with different distances are theoretically analyzed. Modulation transfer functions are derived with the optical distribution function and the sine template contact measurement respectively and compared. The experiment has been carried out, using rectangular grating with the spatial frequency 50 mm-1, and the experimental value of the modulation transfer function is 0.22, which is corrected to be 0.18. The result indicates that this modified modulation transfer function is more accurate, and the performance of the imaging sensor can be appraised more correctly..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1021 (2006)
Instrumentation, Measurement and Metrology
Study of Adaptive Piezoelectric Phase Shifter
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Phase shifter is the important part of the phase shifting interferometer. For its high resolution, rapid response and easy operation, the piezoelectric phase shifter is widely used. Due to the non linear error and micro-displacement, its application is limited. The structure of piezoelectric shifter and its expansion mPhase shifter is the important part of the phase shifting interferometer. For its high resolution, rapid response and easy operation, the piezoelectric phase shifter is widely used. Due to the non linear error and micro-displacement, its application is limited. The structure of piezoelectric shifter and its expansion methods are studied, and the flexible hinge phase shifter with magnifying characteristics is designed. Based on single neural proportional sum derivative (PSD) algorithm, adaptive real-time control is implemented which enhances the performance of the piezoelectric phase shifter by improving the nonlinear performance and depressing the interference of environment. Three piezoelectric ceramics are used in the piezoelectric phase shifter which can be used in the 100 mm aperture lens with 30 μm displacement. The result verifies this method with a precision of 0.01 μm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1027 (2006)
Precompensation for Nonlinear Distortion in Thick Film Photolithography
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Fabrication of large depth microstructure by using thick film photolithography-technology is a considerable option, but effect of nonlinear distortion on the photolithography surface profile quality severely limits its application. For the above reason, a method to correct mask transmissivity function is proposed. The Fabrication of large depth microstructure by using thick film photolithography-technology is a considerable option, but effect of nonlinear distortion on the photolithography surface profile quality severely limits its application. For the above reason, a method to correct mask transmissivity function is proposed. The influences of nonlinear factors such as spatial imaging, propagation, exposure and development process are analyzed. Then, by utilizing the simulated annealing algorithm, transmissivity function of mask is optimized to improve the quality of surface profile of photolighography. Taking a concave cylinder lens as example, the simulated results of developed profile before and after correction are presented, and the volume deviation of profile after correction is only 2.63%. This method obviously improves the quality of surface profile, but does not increase difficulty of design and fabrication of the mask and expense, which is very useful to fabricate microstructure with high fidelity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1032 (2006)
Novel Method for Measuring Coma with Fine Overlay Test Marks
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In order to meet the demand of coma measurement accuracy of lithographic tool projection lens, a novel method for measuring coma based on fine overlay error metrology marks is proposed. The impact of coma on the aerial image of the fine overlay metrology marks is analyzed and the principle of the method is described inIn order to meet the demand of coma measurement accuracy of lithographic tool projection lens, a novel method for measuring coma based on fine overlay error metrology marks is proposed. The impact of coma on the aerial image of the fine overlay metrology marks is analyzed and the principle of the method is described in detail. The sensitivity coefficients of overlay error relative to coma are obtained by the simulation software PROLITH under different numerical aperture and partial coherent factor. The simulation results show that with the conventional illumination condition, the ranges of sensitivity coefficients Kz7 and Kz14 are increased by 27.5% and 34.3% respectively, 20.4% and 22.1% for annular illumination. Compared with the widely used projection lens coma measurement method TAMIS, the accuracy of coma measurement is increased by 20%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1037 (2006)
Integrated Optics
Study on As2S8 Glass Stripe Waveguide Fabrication using Illumination
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In order to fabricate As2S8 stripe waveguide, experimental study on photo-induced refractive index and density changes in As2S8 film is reported. It is found that the refractive index, and density of As2S8 film are enhanced after UV illumination throught testing techniques of prism coupling, X-ray diffraction spectrum In order to fabricate As2S8 stripe waveguide, experimental study on photo-induced refractive index and density changes in As2S8 film is reported. It is found that the refractive index, and density of As2S8 film are enhanced after UV illumination throught testing techniques of prism coupling, X-ray diffraction spectrum and far-infrared spectra of reflection. The visible light absorption spectra of the As2S8 film sample shows that photodarkening does not occur after UV light irradiation. Based on study of these phenomena, UV illumination technique is presented and applied to As2S8 stripe waveguide preparation. This stripe waveguide of As2S8 displays nice characteristic of conducting beam using through guide mode excitation by means of automatic alignment and end-face coupling technique..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1043 (2006)
Development of Broadband Polarizing Beam Splitter/Combiner
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
To Overcome the shortages of conventional polarizing beam splitters, narrow waveband and limited angle range, a polarizing beam splitter/combiner with wide waveband and angle range of 180° is developed. The device is designed with the principle of wire grid polarizer and subwavelength grating structure, and etchedTo Overcome the shortages of conventional polarizing beam splitters, narrow waveband and limited angle range, a polarizing beam splitter/combiner with wide waveband and angle range of 180° is developed. The device is designed with the principle of wire grid polarizer and subwavelength grating structure, and etched with semiconductor technique. Large pass width, acceptable angle and beam splitting angle, high extinction ratio and low insert loss are achieved based on that there exists only zeroth-order diffraction for the polarizing response of one-dimensional metal wire grid polarizer on the incident electromagnetic wave and subwavelength grating. The experiment verifies that the transmission and reflection extinction ratio is beyond 20 dB, insert loss below 0.5 dB. On the home-constructed microstructure testing platform, the transmissivity and reflectivity variation with the incident angle for the p and s components is obtained, which agrees well with simulated result by the rigorous coupled wave approach. The influence of excessive etching on the performance of the beam splitter/combiner during fabrication is analyzed deeply..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1048 (2006)
Optical Waveguide Ring Resonator Filter by Using Ion-Exchanged Glass
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A racetrack waveguide resonator filter was fabricated on K9 glass by ion-exchange in mixed melt salt of AgNO3 and KNO3. The free spectral range of the filter was 0.178 nm, and the contrast of the two output ports were 1.47dB and 6.5 dB, respectively. From the measurement parameters, the splitting ratio of the coupler aA racetrack waveguide resonator filter was fabricated on K9 glass by ion-exchange in mixed melt salt of AgNO3 and KNO3. The free spectral range of the filter was 0.178 nm, and the contrast of the two output ports were 1.47dB and 6.5 dB, respectively. From the measurement parameters, the splitting ratio of the coupler and propagation loss of the resonator were analyzed to be 0.16 and 8.1 dB/cm. The phase shift of 2π was realized by using thermo-optical effect within 16 ℃ temperature change, and the thermo-optical coefficient of the waveguide material was about 1.28×10-5 /℃..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1053 (2006)
Lasers and Laser Optics
Experimental Study on Generalized M2 Factor of Truncated Laser Beams
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A method for the generalized M2 factor measurement and the corresponding data processing have been proposed, which can be widely applied to the truncated and non-truncated laser beams. The integral area for calculating the beam width by using the definition of generalized second-order moments is selected to ensure the A method for the generalized M2 factor measurement and the corresponding data processing have been proposed, which can be widely applied to the truncated and non-truncated laser beams. The integral area for calculating the beam width by using the definition of generalized second-order moments is selected to ensure the energy in the angular domain more than 75% of the total beam energy and the measurement method and steps still follow the relevant ISO standards. The generalized M2 factor of truncated Gaussian beam has been measured. The experimental results for different truncated parameters have been compared with the theoretical results, showing the validness of the method proposed. The results indicate that the generalized M2 factor of truncated laser beam can be measured only by properly modifying the data processing method for the measurement of M2 factor of non-truncated laser beam without additional hardware spending. The method is simple and convenient and its measuring steps also follow the ISO standards..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1057 (2006)
Suppression of Fluctuation of Residual Amplitude Modulation in Electro-Optical Phase Modulators
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Residual amplitude modulation (RAM) in electro-optical phase modulators (EOM) and its influence on the laser frequency shift of iodine-stabilized 532 nm laser are investigated experimentally. The relationships between the EOM crystal temperature and the RAM, as well as stabilized laser frequency are observed. The effecResidual amplitude modulation (RAM) in electro-optical phase modulators (EOM) and its influence on the laser frequency shift of iodine-stabilized 532 nm laser are investigated experimentally. The relationships between the EOM crystal temperature and the RAM, as well as stabilized laser frequency are observed. The effects and problems of using active voltage feedback method to suppress the RAM are researched. An active temperature feedback method is proposed and demonstrated to suppress the RAM fluctuation by controlling the EOM temperature. With this method the suppression of the fundamental component in the RAM spectra overtakes 40 dB. The RAM fluctuation is controlled effectively, and additional frequency fluctuation is induced from adopting the system. The laser frequency stability can achieve or be better than 5×10-15 for the averaging time from 100 s to 104 s, and the stability of indine-stabilized 532 nm laser frequency in a medium and long term is improved greatly..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1063 (2006)
1386 nm Continuous Wave Output from Laser Diode End-Pumped 1386 nm Nd:YVO4 Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Transition spectra in the 4F3/2-4I13/2 transition band of Nd:YVO4 crystal are too weak to form laser oscillation for the small stimulated emission cross section and strong parasitical oscillation, except for the 1342 nm wavelength. By adjusting the loss of the resonant cavity, 1386 nm continuous wave output from fiber Transition spectra in the 4F3/2-4I13/2 transition band of Nd:YVO4 crystal are too weak to form laser oscillation for the small stimulated emission cross section and strong parasitical oscillation, except for the 1342 nm wavelength. By adjusting the loss of the resonant cavity, 1386 nm continuous wave output from fiber coupled laser diode end-pumped Nd:YVO4 laser is achieved, which reaches 305 mW with pump power of 4.24 W, and the slope efficiency is 13.9% with the highest output power. Continuous wave outputs of 1342 nm and 1386 nm are also observed in the experiment. The stimulated emission cross section of Nd:YVO4 crystal at the wavelength of 1386 nm is calculated as about (3±1)×10-19 cm2, according to the pumping threshold energy and experimental data..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1069 (2006)
Surface Modification and Ablation of Polytetrafluorethylene by Excimer Laser Irradiation
[in Chinese], [in Chinese], and [in Chinese]
The surface of polytetrafluoroethylene (PTFE) is modified by the irradiation from a focused excimer laser with wavelength of 248 nm with different energy densities. Scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy are used to investigate the changes of the surface morphology, chemicThe surface of polytetrafluoroethylene (PTFE) is modified by the irradiation from a focused excimer laser with wavelength of 248 nm with different energy densities. Scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy are used to investigate the changes of the surface morphology, chemical composition and structure. The mechanism of interaction between laser and PTFE is further studied. The experimental results indicate that the component of fluorin reduces greatly after laser irradiation and there appear the carbonization of the surface, cross-linking and the formation of oxygen function group. When the laser energy density is increased, C=C bond is produced. These changes of structure can enhance the hardness and adhesion of the surface. The physical properties and chemical structure of the treated samples surface are influenced greatly by the laser energy density, which is an important factor in the process of laser modification and ablation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1073 (2006)
Nonlinear Optics
High-Efficiency First-Order Stokes Conversion in H2 Pumped by a Nd:YAG Laser at 355 nm
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Stimulated Raman scattering (SRS) in H2 and H2:He-Ar mixture gases pumped by a pulsed Nd:YAG laser at 355 nm was investigated. Under 0.5 MPa H2, multi-wavelength output was simultaneously measured from the second-order anti-Stokes to the third-order Stokes, with a total conversion efficiency of 88%, while only the firsStimulated Raman scattering (SRS) in H2 and H2:He-Ar mixture gases pumped by a pulsed Nd:YAG laser at 355 nm was investigated. Under 0.5 MPa H2, multi-wavelength output was simultaneously measured from the second-order anti-Stokes to the third-order Stokes, with a total conversion efficiency of 88%, while only the first- and the second-order Stokes output were obtained under high pressures, with a maximum energy conversion efficiency for the second-order Stokes as high as 44% (i.e., quantum efficiency of 63%). Due to the competitive suppression by high-order Stokes, the energy conversion efficiency for the first-order Stokes is no more than 43% in pure H2. By adding 2 MPa Ar into 3 MPa H2, the second-order Stokes was greatly suppressed and the first-order Stokes output reached an energy conversion efficiency as high as 71% (i.e., quantum efficiency of 83%). The effect of four-wave mixing (FWM) and cascade SRS on multi-order Stokes generation and the influence of inert gas were discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1078 (2006)
Focusing of Bright Beam Induced by Dark Beam in Three-Dimensional Self-Defocusing Media
[in Chinese], [in Chinese], and [in Chinese]
To contract the circular beam symmetrically, the co-propagation of the bright and dark beams in three-dimensional self-defocusing media is studied systematically. Numrical results indicate that the signal beam is induced to the focus and symmetrically contracted during the evolution due to the cross-phase modulation efTo contract the circular beam symmetrically, the co-propagation of the bright and dark beams in three-dimensional self-defocusing media is studied systematically. Numrical results indicate that the signal beam is induced to the focus and symmetrically contracted during the evolution due to the cross-phase modulation effect by the pump beam, when the two beam centers are completely superposed and the initial intensity of the dark pump beam is much stronger than that of the bright signal beam. The effect of the beam parameters on the focusing performance of the signal beam is discussed, and it is found that the larger the initial intensity of the pump beam is, the stronger the focusing of the signal beam is. There exists an optimum value for the initial spot size of the dark beam for the strongest focusing of the signal beam, for a given initial pump intensity. When the wavelength ratio of the pump beam and the signal beam is 0.5～1.5, the focusing of the signal beam decreases with the rise of the ratio. And the theoretical result is validated experimentally..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1083 (2006)
Physical Optics
A Laser Ranging Method Based on Photon Statistics
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel laser ranging method is proposed. This method avoids the processes of timing the pulse intervals or comparing the phase differences, which are done by using complex electric devices in traditional laser ranging methods. In the proposed method, the required range information is analyzed and abstracted mainly by A novel laser ranging method is proposed. This method avoids the processes of timing the pulse intervals or comparing the phase differences, which are done by using complex electric devices in traditional laser ranging methods. In the proposed method, the required range information is analyzed and abstracted mainly by optical ways, and is obtained by comparison of a large number of photons ultimately. Based on birefringence and total internal double reflection effects in single axis crystal, a single block LiNbO3 crystal with special structure is designed as the key device in the proposed method. The results show that this method not only simplifies the structure of devices, but also has a high precision, comparing with the traditional laser ranging methods. So a new thicking way for the laser ranging is provided..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1091 (2006)
Study on Modulation Characteristic of Micro-Electromechanical System Infrared Radiation Sourc
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A new calculation method is adopted aiming at the dynamic charactetristic of a thermal induced micro-electromechanical system (MEMS) infrared radiation source. By calculating the temperature rise dependent on power supply time and power with different initial temperature, the modulation depth of radiation source under A new calculation method is adopted aiming at the dynamic charactetristic of a thermal induced micro-electromechanical system (MEMS) infrared radiation source. By calculating the temperature rise dependent on power supply time and power with different initial temperature, the modulation depth of radiation source under different pulse frequencies is quantitatively reckoned. This meathod is capable of calculating the dynamic characteristics with large modulation depth. The influence of power supply mode and material emissivity is discussed in detail. The results show that adopting constant voltage source obtains a shorter response time than by adopting constant current source or constant power source under the same saturated power condition, thus it is more advantageous for dynamic modulation characteristic improvement. Also, high emissivity material reduces the rise time without regard to other parameters change. Combining the calculated result, a test experiment is carried out to study the frequency response characteristic of a MEMS Pt thin film infrared source, and the experimental result fits the calculation well..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1097 (2006)
Rapid Communications
A Continuous-Wave 714 W Fiber Laser With China-Made Large-Mode-Area Double-Clad Fiber
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A continuous-wave (CW) fiber laser with 714 Watts output power has been obtained from 21 meters Chia-made Ytterbium-doped large-mode-area double-clad fiber. Two high-power collimated beam laser diodes (wavelenth 976 nm) with spatial filter and aspheric lens are used for pumping from the two ends of the fiber. A CW outpA continuous-wave (CW) fiber laser with 714 Watts output power has been obtained from 21 meters Chia-made Ytterbium-doped large-mode-area double-clad fiber. Two high-power collimated beam laser diodes (wavelenth 976 nm) with spatial filter and aspheric lens are used for pumping from the two ends of the fiber. A CW output power of 501 W is obtained under pump power of 760 W with backward pumping scheme. And the maximum output power of 714.5 W is realised under total pump power of 1137 W with double-sided end-pumping scheme, the optical-to-optial efficiency and the slope efficiency whicd respect to the launched pump power are 62.8% and 67%, respectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1119 (2006)
Thin Films
Stratified-Interface Scattering Model for Multilayer Optical Coatings
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A theoretical model calculating the surface total integrated scattering (TIS) of multilayer optical coatings is presented. The new model assumes that the rough interface and surface of the coatings are very thin zones with inhomogeneous micro constructure, which can be substituted by adequate number of homogeneous sub-A theoretical model calculating the surface total integrated scattering (TIS) of multilayer optical coatings is presented. The new model assumes that the rough interface and surface of the coatings are very thin zones with inhomogeneous micro constructure, which can be substituted by adequate number of homogeneous sub-layers, refractive indexes of which are constant and meet the exponential distribution. The formula of TIS is deduced by using the matrix method. For ZrO2 coatings deposited on K9 glasses by the electronic beam evaporation method, the TIS result calculated by the new model is in better conformity with the measured value by the scatterometer than that by the uncorrelated surface roughness model..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1102 (2006)
Effect of Thickness Monitoring Error and Inhomogeneity of Witness Glass on Film Thickness Monitoring
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
By the aid of VC++, the influence of thickness monitoring error and witness glass inhomogeneity on the thickness monitoring of optical films is analyzed. It is found that both thickness monitoring error and witness glass inhomogeneity have effect on the thickness monitoring of optical thin films, and the inhomogeneity By the aid of VC++, the influence of thickness monitoring error and witness glass inhomogeneity on the thickness monitoring of optical films is analyzed. It is found that both thickness monitoring error and witness glass inhomogeneity have effect on the thickness monitoring of optical thin films, and the inhomogeneity of witness glass increases with increase of coating layers. Then a multi-layer coating is fabricated and its monitoring curve is analyzed, it is shown that the theoretical monitoring curve which takes thickness monitoring error and inhomogeneity of witness glass into account is close to the experimental monitoring curve, and such a conclusion is got that thickness monitoring error and witness glass inhomogeneity are the important factors which cause the deviation of experimental monitoring curve from theoretical one. In the end, the calculation method of theoretical monitoring curve is proposed, in which thickness monitoring error and witness glass inhomogeneity error are taken into account. The results are of importance for the automatic thickness monitoring of thin films, especially of non-quarter wave coatings..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1107 (2006)
Optical Properties of ZnO Thin Film Grown by Atmospheric Pressure-Metal Organic Chemical Vapor Deposition Using N2O as Oxygen Precursor
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
High-quality ZnO films were grown on c-Al2O3 substrate by atmospheric pressure-metal organic chemical vapor deposition technique, using a method of three-step growth. DEZn and H2O were used as the Zn and O precursors in both the low and high temperature N2 buffers and N2O was used as O precursor in the main ZnO layer. High-quality ZnO films were grown on c-Al2O3 substrate by atmospheric pressure-metal organic chemical vapor deposition technique, using a method of three-step growth. DEZn and H2O were used as the Zn and O precursors in both the low and high temperature N2 buffers and N2O was used as O precursor in the main ZnO layer. The full width at half maximum (FWHM) of the inclined symmetrical plane (10-12) ω-scan of the ZnO film by double crystal X-ray diffraction method was 350″, indicating the high crystal quality of the ZnO film. Compared with the 10 K low temperature photoluminescence spectra of the H2O-grown ZnO sample, the two-electron satellite peak caused by the hydrogen related neutral donor trapping excition disappeared in that of the N2O-growth ZnO sample. It indicated that hydrogen was not easily introduced into the N2O-growth ZnO film..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1112 (2006)
Property of ZnO Thin Films Grown on Ag-Si(111) Templates by Atmospheve-Pressure Metal Organic Chemical Vapor Deposition
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An Ag layer with thickness of 1.5 nm is deposited on Si(111) substrate by magnetron sputtering in order to protect the Si surface from oxidation. ZnO films with mosaic structure are grown on Ag-Si(111) templates by atmospheric-pressure metalorganic chemical vapor depositon (AP-MOCVD). The micro-crack with orientation cAn Ag layer with thickness of 1.5 nm is deposited on Si(111) substrate by magnetron sputtering in order to protect the Si surface from oxidation. ZnO films with mosaic structure are grown on Ag-Si(111) templates by atmospheric-pressure metalorganic chemical vapor depositon (AP-MOCVD). The micro-crack with orientation character is found on ZnO films with optical microscope, and the crack density is 100 cm-1. X-ray diffraction results show that the highly c-axis oriented ZnO films is obtained. The fullwidth at half-maximum of the (002) ω-scans of double-crystal X-ray diffraction is 1.37°. Free exciton and binding exciton emission accompanied by their LO phonons could be observed from the photoluminescence spectrum at 10 K. All the results show that the metal Ag is an effective buffer layer for the growth of ZnO films on Si(111) substrate with MOCVD method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 26, Issue 7, 1115 (2006)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20