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2005
Volume: 34 Issue 7
39 Article(s)
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Research Article
Propagation of Intense Femtosecond Laser Pulses in Ar Gas and Ar Clusters
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The propagation of intense femtosecond laser pulses(50 fs,10 16 w/cm2) in Ar gas and middle-size Ar clusters is modelled by solving 3D propagation equation numerically.The results show that the intense femtosecond laser pulses propagating in Ar gas will experience ionization-induced modulations, including spectral blThe propagation of intense femtosecond laser pulses(50 fs,10 16 w/cm2) in Ar gas and middle-size Ar clusters is modelled by solving 3D propagation equation numerically.The results show that the intense femtosecond laser pulses propagating in Ar gas will experience ionization-induced modulations, including spectral blueshifting and beam refraction,while self-focusing may occur for the intense femtosecond laser pulses propagating in Ar clusters..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 961 (2005)
Fiber-coupled Diode End-pumped Double Tm, Ho: GdVO4 Laser
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A continuous wave diode-pumped Tm,Ho:GdVO4 laser operating at cryogenic temperature is reported. Tm,Ho∶GdVO~~4 crystal has much stronger and broader absorption spectrum than Tm- Ho-codoped YLF and YAG,and is very favorable for diode pumping. Radiation from a fiber coupled diode (core diameter 0.4 mm, N.A. 0.3) is couplA continuous wave diode-pumped Tm,Ho:GdVO4 laser operating at cryogenic temperature is reported. Tm,Ho∶GdVO_4 crystal has much stronger and broader absorption spectrum than Tm- Ho-codoped YLF and YAG,and is very favorable for diode pumping. Radiation from a fiber coupled diode (core diameter 0.4 mm, N.A. 0.3) is coupled into Tm(5% at.),Ho(0.5% at.)∶GdVO_4 crystal by a pair of achromatic lens for end pumping. Output power of 3.6 W at 2.048 μm is obtained under pump power of 14 W and emission wavelength of 794 nm. The optical-optical conversion efficiency is 25.7% and slope efficiency is 26.6%. Corresponding to the absorbed pumping power, the optical-optical conversion efficiency is up to 35%.Due to cross relaxation between Tm 3+ ions,pumping quantum efficiency of 1.3 is achieved..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 964 (2005)
A 3.6 kW TEA Laser Using Printed Circuit Board Preionization
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Preionization technique is the key technology of TEA CO~~2 lasers to obtain large volume uniform main discharge. The Printed Circuit Board (PCB) preionization technique utilizes a distributing capacitor coupler configuration to produce relatively strong UV preionization around cathode. The combination of appropriate prPreionization technique is the key technology of TEA CO_2 lasers to obtain large volume uniform main discharge. The Printed Circuit Board (PCB) preionization technique utilizes a distributing capacitor coupler configuration to produce relatively strong UV preionization around cathode. The combination of appropriate preionization intensity and better uniformity make it more suitable for producing high-pulse-repetition and high average power laser.20.4 J pulse output energy is obtained from a PCB preionized TEA CO_2 laser. The experimental setup consists of two same laser modules each of which has a 5 cm×4 cm×90 cm discharge volume. The electro-optical conversion efficiency reaches 12.8%. The clearing ratio is over 3 when the laser operates at repetition rate. Average power as high as 3.6 kW is achieved at the maximum repetition rate of 180 Hz..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 968 (2005)
LD-pumped Nd: YVO4/V: YAG Passively Q-switched 1.34 μm Laser
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A LD-pumped Nd∶YVO~~4 laser passively Q-switched at 1.34 μm by using V∶YAG which is a new type of crystal saturable absorber.The relationship between the stability of pulse laser and the small signal transmission of V∶YAG was studied.The results show the laser is stable when the V∶YAG with smaller signal transmission iA LD-pumped Nd∶YVO_4 laser passively Q-switched at 1.34 μm by using V∶YAG which is a new type of crystal saturable absorber.The relationship between the stability of pulse laser and the small signal transmission of V∶YAG was studied.The results show the laser is stable when the V∶YAG with smaller signal transmission is used.When the pump power is 1.6 W,the stability of pulse energy and repetition rate for 4 hours is 15%,10,5% for V∶YAG with small signal transmission of 96%,89%,85%,respectively.The results of average power of 96mW,minimum pulse width (FWHM) of 8.8 ns,pulse repetition rate of 25 kHz,peak power of 436 W and pulse energy of 3.84 μJ were obtained for small signal transmission of 85%..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 971 (2005)
Study on High-Energy Ytterbium-Ions-Doped Fiber Laser
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Operational principle and output characteristics of fiber laser were studied based on the rate equation.The threshold term and expression of output power of fiber laser were given at steady state. Using numerical simulation results,basic parameter of fiber laser was analyzed and demonstrated, and which is the theoreticOperational principle and output characteristics of fiber laser were studied based on the rate equation.The threshold term and expression of output power of fiber laser were given at steady state. Using numerical simulation results,basic parameter of fiber laser was analyzed and demonstrated, and which is the theoretical basis for optimized design of fiber laser.Experimental method of all fiber structure fiber laser was put forward.Single-mode continuous laser output was realized,which is maximal power of 7.5W,wavelength of 1080 nm and half maximum full width of 0.11 nm..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 975 (2005)
Sub-millisecond Optical Switch Array for ION
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A sub-millisecond optical switch operation was reported for an array of 1x2 switches for intelligent optical network (ION). By utilizing a micromachined wedge-shaped double side micro-mirror to implement an input optical beam path change, the design achieved a high level integration of multiple switches on a single subA sub-millisecond optical switch operation was reported for an array of 1x2 switches for intelligent optical network (ION). By utilizing a micromachined wedge-shaped double side micro-mirror to implement an input optical beam path change, the design achieved a high level integration of multiple switches on a single substrate,and significantly reduced mirror traveling distance or angle for switch operation and thus shortened the switch time. An array of four 1×2 switches was fabricated on an aluminum substrate with an overall size of only 60×36×7 mm3 . Performance of the switch array prototype was reported, featuring a fast switch time of less than 750 μs and extremely low cross-talk <-70 dB with an insertion loss of between 0.6 and 0.8 dB. An analysis on switch time was conducted using a commercial finite element analysis software package ANSYS and a good agreement was obtained between the measured and calculated switch time..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 980 (2005)
Optical Propagation Characteristics of All-metal-cladding Rib Waveguide
The convenient analytical method for the all-metal-cladding rib waveguide is presented.The metal-cladding rib waveguide is converted into the two-dimension slab one by using the effective refractive method, then the equation of satisfying effective refractive index and the formula of absorption loss coefficient are derThe convenient analytical method for the all-metal-cladding rib waveguide is presented.The metal-cladding rib waveguide is converted into the two-dimension slab one by using the effective refractive method, then the equation of satisfying effective refractive index and the formula of absorption loss coefficient are derived by the derivation method for the all- metalcladding rib waveguide. Taking this method as an example, optical propagation constant and the loss characteristics for SiO2 have been calculated actually. Some available results are obtained..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 984 (2005)
Imaging and Fourier Transform Properties of GRIN-rod Lens
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Imaging and Fourier Transforming properties of GRIN-rod Lens are discussed firstly.Then the optical spot of GRIN-rod lens is calculated in theory.Taking no account of aberrations,the optical spot size of the lens whose diameter is 1.80 mm is 1.2 μm.Compare the measurement value which is 1.5 μm with the theoretical one,Imaging and Fourier Transforming properties of GRIN-rod Lens are discussed firstly.Then the optical spot of GRIN-rod lens is calculated in theory.Taking no account of aberrations,the optical spot size of the lens whose diameter is 1.80 mm is 1.2 μm.Compare the measurement value which is 1.5 μm with the theoretical one,they are almost identical with each others.It also proves the theoretical analysis is reasoned..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 988 (2005)
Fabricating Fiber Bragg Gratings with Triangular Spectrum Using Nonlinear Double-Exposure
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In this paper, a novel nonlinear double-exposure technique for fabricating fiber Bragg gratings with triangular spectrum is proposed. The spectrum of fiber Bragg grating can be controlled by double exposure technique. The first exposure is used to control the resonant wavelength of fiber grating by directly irradiatingIn this paper, a novel nonlinear double-exposure technique for fabricating fiber Bragg gratings with triangular spectrum is proposed. The spectrum of fiber Bragg grating can be controlled by double exposure technique. The first exposure is used to control the resonant wavelength of fiber grating by directly irradiating the naked photosensitive fiber. The second one is to form the grating to control its reflectivity through an ordinary Bragg phase mask. Considering the multi-decaying-exponential relationship between photo-induced index increment of photosensitive fiber and its irradiating dose, nonlinear double-exposure profiles are calculated by our self-designed software. The triangular fiber Bragg grating is obtained with DCS-01 photosensitive fiber by using a scanning system. As a result, the bottom width and the reflectivity of the grating is 1.24 nm and 0～64%,respectively. As a demodulation device, a triangular fiber Bragg gratings is very important in a fiber grating sensing system..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 993 (2005)
Technical Modeling of X-cut H: LiNbO3 Optical Waveguides
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Technical modeling of x-cut H∶LiNbO~~3 optical waveguides is researched by prism coupler at the wavelength of 532 nm and 1310 nm.For optical waveguides proton-exchanged in pure benzoic acid at 150℃,180℃ and 200℃, relationships between exchanged thickness and exchanged time are given, respectively,and on this base,a relTechnical modeling of x-cut H∶LiNbO_3 optical waveguides is researched by prism coupler at the wavelength of 532 nm and 1310 nm.For optical waveguides proton-exchanged in pure benzoic acid at 150℃,180℃ and 200℃, relationships between exchanged thickness and exchanged time are given, respectively,and on this base,a relation curve of diffussion coefficient of proton-exchange to exchanged temperature is plotted.For the waveguides proton-exchanged at 180℃ and annealed at 350℃,the changes of surface refractive index increment and effective thichness with annealing time are obtained.The results can be used to design and fabricate the low loss α phase single mode waveguides..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 996 (2005)
The Research of Location About the Infrared Multi-sites System Based on the Weighted Least Square Method
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Based on the weighted least square method, the mathematics model of the location algorithm about infrared multi-sites passive system is established,meanwhile the equation is offered and the realization of the algorithm is discussed. Because of the weighted least square method, much detected information can be combined Based on the weighted least square method, the mathematics model of the location algorithm about infrared multi-sites passive system is established,meanwhile the equation is offered and the realization of the algorithm is discussed. Because of the weighted least square method, much detected information can be combined efficiently,and the positional accuracy and reliability of system can be raised. The simulation result show that a large number of sites relates to a proper relative position to the sites,and a short distance between the target and sites corresponds with a accurate position..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1001 (2005)
The Experiments and Numerical Value Analysis to Dynamical Process of Bacteriorhodopsin
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In the experiments, excited by a laser of 532 nm, the chemically enhanced bacteriorhodopsin″s state conversions are researched at real-time by using the method of different absorption spectrum. The experiments show that there is a steady middle process at 585 nm obviously. From the experiments and molecular dynamics, aIn the experiments, excited by a laser of 532 nm, the chemically enhanced bacteriorhodopsin″s state conversions are researched at real-time by using the method of different absorption spectrum. The experiments show that there is a steady middle process at 585 nm obviously. From the experiments and molecular dynamics, a model is set up, which suits for the different absorption spectrum and studies the simulation and numerical value analysis to bacteriorhodopsin′s dynamical process after it is excited by the laser..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1005 (2005)
A Z-Scan Theory Based on Diffraction Theory with Consideration of Two-photon Absorption
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Based on Fresnel-Kirchhoff diffraction theory, a diffraction model of a nonlinear optical medium to a Gaussian beam is built. The propagation behavior of the Gaussian beam passing through the nonlinear optical medium is theoretically deduced and numerically simulated, which can explain the Z-scan phenomenon from a new Based on Fresnel-Kirchhoff diffraction theory, a diffraction model of a nonlinear optical medium to a Gaussian beam is built. The propagation behavior of the Gaussian beam passing through the nonlinear optical medium is theoretically deduced and numerically simulated, which can explain the Z-scan phenomenon from a new approach. From this theory, a unified equation is derived, which can describe both the closed-aperture Z-scan curve and the open-aperture Z-scan curve with consideration of the two-photon absorption. It provides a new way to calculate the nonlinear refraction index and the two-photon absorption coefficients. Numeric simulation shows that for the closed-aperture Z-scan considering the two-photon absorption, the simulation results are well consistent with the conventional theory. For a given open-aperture Z-scan curve, the two-photon absorption coefficient computed by the new Z-scan theory is 1/3 of the value fitted by the conventional Z-scan theory, whereas other conclusions are identical to the.......
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1010 (2005)
The Application of An Modified Finite-Difference Beam Propagation Method in the AWG
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Based on the Helmholtz equation, the Finite-Difference Beam Propagation Method in the convention is modified and a new arithmetic is advanced.Comparing the modified method with the traditional method and calculating the transmission mode in the AWG by the new method , the conclusion is gotten:the modified method can caBased on the Helmholtz equation, the Finite-Difference Beam Propagation Method in the convention is modified and a new arithmetic is advanced.Comparing the modified method with the traditional method and calculating the transmission mode in the AWG by the new method , the conclusion is gotten:the modified method can calculate precision of the mode and improve the accuracy..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1015 (2005)
Photoacoustic Imaging with Attenuation Rectification of Different Frequent Components of Photoacoustic Signal
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The influences of attenuation coefficients of photoacoustic signals, which depends on frequencies, on the quality of reconstructed photoacoustic images has been explored. It reveals that the attenuation coefficients of low frequent components are less than those of high frequencies, and the latter are more important foThe influences of attenuation coefficients of photoacoustic signals, which depends on frequencies, on the quality of reconstructed photoacoustic images has been explored. It reveals that the attenuation coefficients of low frequent components are less than those of high frequencies, and the latter are more important for photoacoustic imaging with high resolution. Based on the ultrasonic attenuation theory, the method of photoacoustic imaging with rectification of the attenuation of different frequent component was performed. The experiments results show that this method improves the resolution of reconstructed images, and the reconstructed images resolution improved from 0.3 mm to 0.2 mm. A Q-switched Nd∶YAG laser operating at 1064 nm was used as light source. The laser had a pulse width of 6ns and a repetition frequency of 20 Hz. A needle PVDF hydrophone with diameter of 1 mm was used to detect photoacoustic signals..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1019 (2005)
The Difference of Chlorphyll Fluorescence Dynamics Process and the System of Photosynthetic Pigment in Leaf of Spinach and Tobacco Under the Action of Low Level Microwave Electromagnetic Field
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Under the action of low level microwave electromagnetic field of 300MHz,the changes of chlorophyll fluorescence dynamics process and photosynthetic pigment in leaf of spinach and tobaccoare are different.When the fluorescence dynamics parameters F~~0 and F~~ VI /F~~V of spinach decrease,ΔF~~V/T and F~~V/F~~m increase. Under the action of low level microwave electromagnetic field of 300MHz,the changes of chlorophyll fluorescence dynamics process and photosynthetic pigment in leaf of spinach and tobaccoare are different.When the fluorescence dynamics parameters F_0 and F_ VI /F_V of spinach decrease,ΔF_V/T and F_V/F_m increase. The fluorescence dynamics parameter F_0 of tobacco increases,while ΔF_V/T and F_V/F_m decrease. There is a difference between photosynthetic pigment of spinach and tobacco. The content of chlorophyll in leaf of spinach and tobacco decrease,but the content of carotenoid in leaf of spinach increase. These results show that low level microwave electromagnetic field leads to the decrease of potential active of reaction center PSⅡand the photochemical efficiency of PSⅡ in leaf of tobacco.Spinach can keep the photosynthesis in leaf through the change of heterogeneity of PSⅡand the increases of carotenoid..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1023 (2005)
Spectral Research on Delayed Fluorescence of Chloroplasts at Different Concentration
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Delayed fluorescence (DF) spectrum is an efficient method in study transportation of electron in photosynthesis. In the light of the great difference of spectrum characteristic between the experimental results in reference [1] and what have been reported, in this paper the spectrum of DF of chloroplast at different conDelayed fluorescence (DF) spectrum is an efficient method in study transportation of electron in photosynthesis. In the light of the great difference of spectrum characteristic between the experimental results in reference [1] and what have been reported, in this paper the spectrum of DF of chloroplast at different concentrations was studied by using different spectral analysis methods. Experimental results show that the chlorophyll P700 in PS I absorbs the 685 nm component emitted from PS II is increasing as the chloroplast concentration increases, which results in the peak value at 730 nm and nearly disappearance of apex at 685 nm in DF spectrum. Experimental results indicate that the 730 nm component of DF spectrum is the result of re-absorption DF spectrum of 685 nm component, which emitted from PS II as the PSⅠacts on chlorophyll P700. The results in this paper will be of benefit for us for understanding and further study of the mechanism of different components in delayed fluorescence..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1028 (2005)
Experimental Study on the Dependence of DPB SFS'Performance on Er-Doped Fiber Length
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The experimental investigations on double-pass backward Erbium-doped superfluorescent fiber source(DPB SFS) were presented. The depencence of the mean wavelength, spectral linewidth, and thermal stability on the Erbium-doped fiber length were measured. The source intrinsic thermal coefficents for several fiber length wThe experimental investigations on double-pass backward Erbium-doped superfluorescent fiber source(DPB SFS) were presented. The depencence of the mean wavelength, spectral linewidth, and thermal stability on the Erbium-doped fiber length were measured. The source intrinsic thermal coefficents for several fiber length were measured by rapidly cycling the fiber temperature between -20℃ and 60℃. The curve of the intrinsic thermal coefficient and the stability of DPB SFS mean wavelengh versus fiber length under several temperature point were obtainted. The result of experiments has significent reference value to the selection of devices and proper design of Erbium-doped superfluorescent fiber sources..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1032 (2005)
The response of side-polished FBG to external refractive index
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Fiber Bragg grating (FBG) cannot be directly used as gas or liquids sensors, because it is not sensitive to external refractive index.By side-polished,the cladding layer of one side of FBG can be reduced to several micrometers.The radiation field can reach the external medium.When the external refractive index changes,Fiber Bragg grating (FBG) cannot be directly used as gas or liquids sensors, because it is not sensitive to external refractive index.By side-polished,the cladding layer of one side of FBG can be reduced to several micrometers.The radiation field can reach the external medium.When the external refractive index changes, the effective refractive index of fiber changes and the center wavelength of D-shaped FBG shifts accordingly.In the experiment,the NaCl solution with different concentration is used to change the external refractive index of FBG.The center wavelength of D-shaped FBG shifts when the concentration of NaCl solution changes.The relationship between the offset of wavelength and the concentration of NaCl solution is approximately linear.In addition,the relationship between the transmitting power and the concentration of NaCl solution is also approximately linear..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1036 (2005)
The Performance Analysis of the OCDMA System with the Encoder/decoder Based on Step Chirped Fiber Bragg Gratings
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The performance of optical code-division multiple-access (OCDMA) system with an encoder/decoder based on step chirped fiber bragg gratings (SCFBGs) is presented. In the system, the multiple access interference (MAI) is the main noise and the unsuccessfully decoded pulse is assumed to be a Gaussian random process. SimulThe performance of optical code-division multiple-access (OCDMA) system with an encoder/decoder based on step chirped fiber bragg gratings (SCFBGs) is presented. In the system, the multiple access interference (MAI) is the main noise and the unsuccessfully decoded pulse is assumed to be a Gaussian random process. Simulation shows that longer code length and narrow pulse improve the performance of system. And when threshold is 0. 7, the best bit error rate (BER) can be obtained for this OCDMA system..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1039 (2005)
Analysis for Frequency Chirp of All-Optical Wavelength Converter Based on Semiconductor Laser
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The frequency chirp of the converted signal is analyzed by using the rate equation, in addition, the amplified input signal is considered. During the course of the conversion, the amount of carriers in laser cavity will be changed when signal light is injected. As a result, the frequency of the output signal light willThe frequency chirp of the converted signal is analyzed by using the rate equation, in addition, the amplified input signal is considered. During the course of the conversion, the amount of carriers in laser cavity will be changed when signal light is injected. As a result, the frequency of the output signal light will be changed, and the chirp of frequency will occur.The results show that higher injected current can restrain the frequency chirp effectively,and higher input optical power can also do that,meanwhile,good extinction ratio is ensured..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1042 (2005)
A New Technique for Eliminating the Effect of Background Energy Fluctuation on the Harmonic Signals of Wavelength Modulation Spectroscopy
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When the voltage of the PZT on the back mirror of the ECDL is scanned, there exits a phase difference of the frequency variation and the background energy variation. It is realized that the absorption signal and background signal can be obtained separately at the same detector by use of the upper laser character and a When the voltage of the PZT on the back mirror of the ECDL is scanned, there exits a phase difference of the frequency variation and the background energy variation. It is realized that the absorption signal and background signal can be obtained separately at the same detector by use of the upper laser character and a lock in amplifier. A better 1f-4f harmonic signals can be obtained. If the phase difference doesn′t exit, the background harmonic signal cannot be eliminated. It is very important for setting up a miniature high sensitivity gas sensor..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1046 (2005)
Principle and Design of Optical Fiber Angular Displacement Sensor Based on Sensitive Fabry-Perot Cavity
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A novel optical fiber angular displacement which can be used to measure micro angular displacement (second level) and all angle continuously is introduced.Basing on the principle of micro resonance cavity, especially on optical Fabry-Perot cavity,the linear relation between beam intensity and angular displacement with A novel optical fiber angular displacement which can be used to measure micro angular displacement (second level) and all angle continuously is introduced.Basing on the principle of micro resonance cavity, especially on optical Fabry-Perot cavity,the linear relation between beam intensity and angular displacement with special beam has been researched.By using of optical fiber technology, sensing technology and micro mechanical technology,the sensor used in some special circumstance is produced for measuring angular displacement accurately..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1049 (2005)
A Flat-Top Interleaver Based on a M-Z Interferometer with Two Ring Cavities
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The theory investigation of a flat-top optical interleaver with two ring cavities in a M-Z interferometer is present. We find the optimum coupling angle of the two two ring cavities which meet the needs for DWDM. The result indicates that the interleaver with two ring cavities can simultaneously produce a 0.5 dB passbaThe theory investigation of a flat-top optical interleaver with two ring cavities in a M-Z interferometer is present. We find the optimum coupling angle of the two two ring cavities which meet the needs for DWDM. The result indicates that the interleaver with two ring cavities can simultaneously produce a 0.5 dB passband and a 25 dB stopband wider than with only one ring cavity. Influence on its transmission characteristics by the coupling angle is also analyzed..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1053 (2005)
A Study on a Novel Fiber-Optic Accelerometer Using a GRIN Lens
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In this paper, a novel Fiber-Optic Accelerometer was studied. It demonstrates the operational principle and structure design of the three-fiber accelerometer using a GRIN lens. This sensor consists of three fibers, one GRIN lens and a block. In addition, the effects of angular misalignment are calculated based on the aIn this paper, a novel Fiber-Optic Accelerometer was studied. It demonstrates the operational principle and structure design of the three-fiber accelerometer using a GRIN lens. This sensor consists of three fibers, one GRIN lens and a block. In addition, the effects of angular misalignment are calculated based on the analysis of the coupled power. It′s reasonable in theory and easy to fabricate in practice. This sensor is novel and small-scale in physical structure, and it also offers potential precision. Altogether, it is a multi-purpose fiber-optic accelerometer..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1057 (2005)
Three-component Hybrid-integrated Optical Acceleration Seismic Geophone Based on Photoelastic Waveguide
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In order to provide a high resolution wide band geophone for three-dimensional seismic geophone, the three-component hybrid-integrated optical acceleration seismic geophone is designed. Analysing the photoelastic effect of LiNbO~~3 waveguide applied arbitrary-direction acceleration. The Mach-Zehnder interferometer is rIn order to provide a high resolution wide band geophone for three-dimensional seismic geophone, the three-component hybrid-integrated optical acceleration seismic geophone is designed. Analysing the photoelastic effect of LiNbO_3 waveguide applied arbitrary-direction acceleration. The Mach-Zehnder interferometer is realized by symmetrical Y-branching waveguide,waveguide phase modulator and two waveguide polarizers, which are monolithically integrated on an X-cut, Y-propagating LiNbO_3 substrate. The results reveal that the accelerometer has wide band and good linearity. The main design parameters of the geophone system is as following: natural frequency:4300 Hz;phase detection sensitivity Δ/a: 1.81×10 -4 rad/m·s -2 ;work frequency range: 3~1506 Hz...
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1062 (2005)
The Tracking Method of Digital Speckle Correlation Using the Sequential Dynamical Speckle Patterns and its Applications
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Based on analyzing the speckle field′s characteristic,the tracking method of digital speckle correlation using the sequential dynamical speckle patterns was presented .This method can bridge the gap that the ordinary speckle correlation does not suit the large deformation measurement,and increase the applied fields of Based on analyzing the speckle field′s characteristic,the tracking method of digital speckle correlation using the sequential dynamical speckle patterns was presented .This method can bridge the gap that the ordinary speckle correlation does not suit the large deformation measurement,and increase the applied fields of digital speckle.Through this method,the large-scale dynamical displacement can be measured and the process of deformation in surface can be analyzed..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1066 (2005)
Iterative Double Random Phase Encryption Based on Pixel Scrambling Technology
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A novel encryption based on iterative double random phase encoding and pixel scrambling technology is proposed. The principle of pixel scrambling method is described, and good results are given by numerical simulation used the proposed method. It is shown from numerical simulation that the original image can been reconA novel encryption based on iterative double random phase encoding and pixel scrambling technology is proposed. The principle of pixel scrambling method is described, and good results are given by numerical simulation used the proposed method. It is shown from numerical simulation that the original image can been reconstructed only when part of the encrypted image is used by this method. The relationship curves of the energy, noise and SNR of the decoded image via the pixels number of the decrypting image is given. By comparing the proposed method with the double random phase encryption, it comes to the conclusions that this method has better performance than the double random phase encryption, and the SNR of the decoded image will not decrease due to pixel scrambling. Finally an optical approach to realize the pixel scrambling is also proposed..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1069 (2005)
The Technique of Displacement Separation in ESPI and Its Application in 3-D Displacement Measurement
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A novel method for 3-D displacement measurement is presented in the paper by using isolating out-of-plane displacement from in-plane displacement. A reference is added to the dual-beam symmetrical illumination system and shared by the two illumination beams, which are separately used to illuminate the test object. WithA novel method for 3-D displacement measurement is presented in the paper by using isolating out-of-plane displacement from in-plane displacement. A reference is added to the dual-beam symmetrical illumination system and shared by the two illumination beams, which are separately used to illuminate the test object. With the help of phase-shifting techniques, two phase maps that include out-of-plane and in-plane displacement can be obtained. Theoretical analysis shows that out-of-plane displacement can be separated from in-plane displacement only by simple calculation of phase. In perpendicular the in-plane displacement can be measured directly by dual-beam symmetrical illumination system. When the technique is applied to an oil pump in diesel engine, 3-D displacement fields of the pump are successfully measured. It shows that this technique provides a new effective approach to 3-D displacement measurement and a new method for intensity and rigid of diesel engine elements analysis..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1074 (2005)
Some Key Problems about the Design of IR Thermal Imaging Fish-eye Lens
The series formula and its corresponding differential equation of fish-eye lens′ stop spherical aberration have been brought forward. Calculating the approximation of the stop spherical aberration according to these formulas,and then adopting iteration, we can confirm the entrance pupil′s position and primary ray accurThe series formula and its corresponding differential equation of fish-eye lens′ stop spherical aberration have been brought forward. Calculating the approximation of the stop spherical aberration according to these formulas,and then adopting iteration, we can confirm the entrance pupil′s position and primary ray accurately. Furthermore,it analyzes the stop′s coma,discusses the special “conjugate” relation between aperture stop and entrance pupil, and how to improve the uniformity of image plane illuminance by using aberration vignetting.Ray′s total reflection or no-intersection at refracting surface is called “ray overflow”.Frequent ray overflows in the optical automatic design of fish-eye lens makes its CAD very hard.Using Aitkin Interpolation to fill up the intersection points of overflow-rays at image plane can ensure the optimization process persistently to go along,and then clearing up the overflow gradually.In the end,it expounds the successive approach method to confirm the boundary of abaxial beams,a.
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1078 (2005)
Design of High-temperature Tv Camera
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The designing method of high-temperature TV optical camera was discussed; the problem of the material which used in this case, the parameters and the direction pointing of the optical axis were analyzed. Three times imaging system has been used to realize the objective. By maintaining the little diameter of all lens inThe designing method of high-temperature TV optical camera was discussed; the problem of the material which used in this case, the parameters and the direction pointing of the optical axis were analyzed. Three times imaging system has been used to realize the objective. By maintaining the little diameter of all lens in the system the whole system has been elongated. And the evaluation result of the designed system were showed,the outcome identified that the system can work well under large variety range of temperature, the idea which design this optical system could be adopted by other high temperature optical system..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1081 (2005)
Light Distribution and Localization in One-dimensional Periodic Structure
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The light distribution and localization in different kinds of one dimensional periodic structure (PS) are studied by using the method of transfer matrix. The results show that when light incident with the band gap frequency, most part of light is reflected and an attenuated standing wave exists in the PS. The emphasis The light distribution and localization in different kinds of one dimensional periodic structure (PS) are studied by using the method of transfer matrix. The results show that when light incident with the band gap frequency, most part of light is reflected and an attenuated standing wave exists in the PS. The emphasis is placed on the localization of light with the frequency of band gap edge in the PS. By introducing appropriate defect layers inside the PS,light localization can be extremely enhanced. In addition, the different distributions induced by light incident from the left side and from the right side of special PS embedded with definite defect layers would be very useful for the optical diode realization through light nonlinear modulation. In absorptive PS, light field attenuates rapidly with the increase of depth and extinction coefficient..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1086 (2005)
Calculation of Aberrations Introduced by a Crystal Components
A birefringent ray-tracing package based on the mathematical software is established.The calculating method of wave aberration is also presented. Using the package, various aberrations for bifocus lens and the relationship between the aberrations and titled angle of incident beam are calculated. The advantage of the paA birefringent ray-tracing package based on the mathematical software is established.The calculating method of wave aberration is also presented. Using the package, various aberrations for bifocus lens and the relationship between the aberrations and titled angle of incident beam are calculated. The advantage of the package is that the calculations of various physical quantities are quite distinct. These calculations provide a theoretical base for improving design of crystal element..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1090 (2005)
Bandgap Extension of Disordered 1D Ternary Photonic Crystals
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Bandgap properties of disordered one-dimensional (1D) ternary photonic crystals are investigated by optical transfer matrix method for the first time . The results show that disordered structure provides strikingly extended bandgap compared with the corresponding periodic structure. The more ingredient of disordered diBandgap properties of disordered one-dimensional (1D) ternary photonic crystals are investigated by optical transfer matrix method for the first time . The results show that disordered structure provides strikingly extended bandgap compared with the corresponding periodic structure. The more ingredient of disordered dielectric multilayers adopted in the calculation, the wider stop band will be obtained. The influence of degree of disorder D and contrast of high and low refractive indices to the photonic bandgap are also calculated and discussed..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1094 (2005)
A Method to Expand the Dynamic Range of a Hartmann-Shack Sensor Deduced from the Unwrapping Algorithm and the Mask Technique
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A method of expanding the dynamic range of a Hartmann-Shack (H-S) sensor for measuring the eye′s aberration is proposed.It is a combination of unwrapping algorithm and mask technique,which greatly increases the dynamic range of H-S system. The experimental data shows that it performs well even in the case where the unwA method of expanding the dynamic range of a Hartmann-Shack (H-S) sensor for measuring the eye′s aberration is proposed.It is a combination of unwrapping algorithm and mask technique,which greatly increases the dynamic range of H-S system. The experimental data shows that it performs well even in the case where the unwrapping method is limited.It also shows that the measurable maximum curvature can be greatly improved compared with the mask technique.When a spherical wavefront incidents,the measurable minimum curvature radius can be reduced from 75 mm to 10 mm by this method,compared with the the mask technique.Actually since it overcomes the limitation of unwrapping algorithm,much higher local curvature can still be measured..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1099 (2005)
Several Problems about Optimization of a Practical Real-time Temperature Measurement System
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Based on the Kirchhoff law, a practical temperature real-time measurement system using laser diode and LiTaO~~3 Pyroelectric detector is presented. According to the curves of spectral radiance and relative temperature measurement sensitivity versus λT, working wavelength range of the system is given. By means of analyzBased on the Kirchhoff law, a practical temperature real-time measurement system using laser diode and LiTaO_3 Pyroelectric detector is presented. According to the curves of spectral radiance and relative temperature measurement sensitivity versus λT, working wavelength range of the system is given. By means of analyzing the relationships between sizes of cooled shelter plate and positioning method and working wavelength, and atmospheric infrared transmission, working wavelength of the system is determined. According to the effect on temperature measurement accuracy by sizes of cooled shelter plate and positioning method,H/R values are discussed. And at the same time, anti-jamming ability and temperature measurement inaccuracy are also analyzed. Five main reasons resulted in temperature measurement uncertainty are presented. And the two are briefly discussed. Temperature measurement uncertainty exceeds 0.3%..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1103 (2005)
A Video Stabilization Algorithm Based on Feature Tracking
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A video stabilization algorithm is presented based on the feature window tracking. First, the proposed algorithm extracts the corner-points as feature from the specified reference frame. Then, based on the fuzzy Kalman filtering, the extracted features are tracked with window-matching method from the succeed frames. ByA video stabilization algorithm is presented based on the feature window tracking. First, the proposed algorithm extracts the corner-points as feature from the specified reference frame. Then, based on the fuzzy Kalman filtering, the extracted features are tracked with window-matching method from the succeed frames. By registering the corresponding feature windows, the motion parameters of the camera can be calculated between the reference frame and succeed frames. Finally, vibration of images due to camera shake is stabilized with motion compensation. The experimental results illustrate that the proposed algorithm is effective and robust with low computational complexity..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1108 (2005)
Signal Processing of Quadrature Double Paths Optical Current Transfomer
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An approach to implementing quadrature double paths OCT and the corresponding signal processing method is presented, meeting the real time processing requirement of electric power transient protection. The current signal can recover directly through the double paths while suppressing the effects of ripples in optical pAn approach to implementing quadrature double paths OCT and the corresponding signal processing method is presented, meeting the real time processing requirement of electric power transient protection. The current signal can recover directly through the double paths while suppressing the effects of ripples in optical paths. By over sampling in data converting and advanced digital signal processing technique, the response delay to transient failure is lowered down and the detecting performance is improved.The experiment proves this method has lower processing delay and higher precision than the conventional one..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1113 (2005)
Quantum Optics
Cavity Field Spectra of Two Atoms Interacting with Two-mode Field in Superposition States
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The cavity field spectra of two atoms interacting with two-mode field with different coupling constant via two-photon resonant transition processes are investigated. The results for the initial fields in coherent state or squeezed vacuum state are presented. The effects of relative coupling constant R=g~~2/g~~1 and iniThe cavity field spectra of two atoms interacting with two-mode field with different coupling constant via two-photon resonant transition processes are investigated. The results for the initial fields in coherent state or squeezed vacuum state are presented. The effects of relative coupling constant R=g_2/g_1 and initial field intensity on the spectrum structure are discussed. When the two modes are both in coherent states, the each mode spectrum appears two peeks for small R and three peeks for R≈1. When the two modes are both in squeezed vacuum states, the complicated multi-peak structure appears for weak fields and single classical resonance peak appears for strong field..
Acta Photonica Sinica
- Publication Date: Jul. 01, 2005
- Vol. 34, Issue 7, 1117 (2005)
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