Journals >Acta Photonica Sinica
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2005
Volume: 34 Issue 9
38 Article(s)
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Research Article
Laser-diode Array Pumped Nd: YAG/KTP Continuous Wave 589 nm Laser with Intracavity Sum-frequency Mixing
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A laser diode array pumped Nd∶YAG laser that generates simultaneous laser action at wavelength 1064 nm and 1319 nm was reported.Nonlinear optical crystal KTP was used as intracavity sum frequency crystal.Using type Ⅱ critical phase-match,a yellow laser at 589 nm was obtained by 1064 nm and 1319 nm intracavity sum-frequA laser diode array pumped Nd∶YAG laser that generates simultaneous laser action at wavelength 1064 nm and 1319 nm was reported.Nonlinear optical crystal KTP was used as intracavity sum frequency crystal.Using type Ⅱ critical phase-match,a yellow laser at 589 nm was obtained by 1064 nm and 1319 nm intracavity sum-frequency mixing.With an incident pump laser of 12 W,the maximum output power of 430 mW was obtained.The optical-to-optical conversion was up to 3.6%.The M~2 beam quality factor of the sum-frequency mixed yellow laser was less than 1.2.Experimental results show that the intracavity sum-frequency mixing is an effective method for obtaining 589 nm laser.Also it can be applied to other transition wavelengths in other laser crystals to obtain more all-solid-state lasers with different wavelengths..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1281 (2005)
A Power-Equilibrium Tunable C+L band Erbium-doped Fiber Laser
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A power-equilibrium tunable C+L band Erbium-doped fiber laser is proposed and demonstrated,Which is based on Erbium-doped fiber ring,and a FP filter incorporated with a tunable bandpass filter in the ring.At the same time,the Auto-Power-Control(APC) technique is used to proportion the output power of the laser.With widA power-equilibrium tunable C+L band Erbium-doped fiber laser is proposed and demonstrated,Which is based on Erbium-doped fiber ring,and a FP filter incorporated with a tunable bandpass filter in the ring.At the same time,the Auto-Power-Control(APC) technique is used to proportion the output power of the laser.With wide tunable range from 1525 nm to 1612 nm,the sidemode suppression ratio of the laser is more than 55 dB.The output power variation is less than +/-0.1 dB over the running range..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1285 (2005)
LD-pumped Nd: YAG Outcavity Fourth Harmonic Generation High Power Ultraviolet Laser
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A diode-pumped,Cr∶YAG passively Q-switched Nd∶YAG laser with an ultraviolet output at 266 nm is studied.Usinga LDA with 15 W,when the incident pump power was 12 W,the passively Q-switched average power infrared output power reached 2.2 W,and the period of the pulse was 40 μs,and the width of the pulse was 18 ns,and theA diode-pumped,Cr∶YAG passively Q-switched Nd∶YAG laser with an ultraviolet output at 266 nm is studied.Usinga LDA with 15 W,when the incident pump power was 12 W,the passively Q-switched average power infrared output power reached 2.2 W,and the period of the pulse was 40 μs,and the width of the pulse was 18 ns,and the peak power rose up to 4.9 kW.Taking KTP as the second harmonic generation crystal,532 nm green light average power was 850 mW;Taking BBO crystal for fourth harmonic generation outcavity,266 nm ultraviolet average output power was 215 mW,the efficiency of green to ultraviolet conversation was 25.2.%,and the efficiency of infared to ultraviolet conversation was 9.8%..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1289 (2005)
Supercontinuum Generation in Photonic Crystal Fibers Depends on Pump Wavelengths
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The Ti:sapphire Optical Parametric Amplifier was applied as the pump source with the output wavelength tuning.Supercontinuum generation in photonic crystal fibers was researched with different pump wavelengths.It was concluded that the SC generation was depended on the pump wavelength,and the difference group velocitieThe Ti:sapphire Optical Parametric Amplifier was applied as the pump source with the output wavelength tuning.Supercontinuum generation in photonic crystal fibers was researched with different pump wavelengths.It was concluded that the SC generation was depended on the pump wavelength,and the difference group velocities in the two sides of the zero dispersive wavelength of the PCF and the OH absorption at about 1.4 μm in the PCF affected the flatness of the generated supercontinuum.When the pump wavelength lied further away from the zero dispersive wavelength,the flatness was reduced,even in the visible region the blue-shift peaks were separated and didnot come into being supercontinuum.Supercontinuum with a broad bandwidth of 300 nm to 1350 nm was generated with the pump wavelength of 1.2 μm,and the generated spectral bandwidth was beyond two octaves..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1293 (2005)
End Deformation's Experiment and its Computer Mimic in LD end Pumped Nd:YAG Crystal
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The end deformation,which is one of the thermal lens of the diode pumped Nd∶YAG is discussed by computer simulation with two different pumped light profile.First of all,Nd∶YAG′s heat model and theory model are built up,then the temperature field is calculated.Under the define condition,the deformation′s distribution isThe end deformation,which is one of the thermal lens of the diode pumped Nd∶YAG is discussed by computer simulation with two different pumped light profile.First of all,Nd∶YAG′s heat model and theory model are built up,then the temperature field is calculated.Under the define condition,the deformation′s distribution is plotted and the focal lens of the end deformation are known.And the experiment aims at a further a study of the thermal effects caused by the end deformation..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1297 (2005)
Multi-wavelength Injection-locking Using Fabry-Perot Laser Diode
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TE mode has larger cord coefficient and reflective index than TM mode in Fabry-Perot laser diode,when they realize injection locking without power less.The signal from TE mode increases,meanwhile,the signal from TM mode decreases.This character makes Fabry-Perot laser diode like a polarizer.Using the principle of injecTE mode has larger cord coefficient and reflective index than TM mode in Fabry-Perot laser diode,when they realize injection locking without power less.The signal from TE mode increases,meanwhile,the signal from TM mode decreases.This character makes Fabry-Perot laser diode like a polarizer.Using the principle of injection locking for Fabry-Perot laser diode,we transfered the polarized light into part polarized light,reducing the polarization sensitivity for the transmission signal,improving the quality of the transmission signal.Besides,multi-wavelength injection-locking was demonstrated by using Fabry-Perot laser diode for the first time..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1301 (2005)
Electrical Pulse-Shaping System on the High Power Laser System
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The arbitrary waveform generator(AWG) has been developed by using GaAs field-effect transistors(FETs) and microstrip technology.The shaped electrical waveform can be adjusted.The Full-Width-Half-Maximum(FWHM) is from 0 to 3.5 ns and amplitude from 0 to 5 V.Timing precision is 200 ps.The rise time of the shaped square eThe arbitrary waveform generator(AWG) has been developed by using GaAs field-effect transistors(FETs) and microstrip technology.The shaped electrical waveform can be adjusted.The Full-Width-Half-Maximum(FWHM) is from 0 to 3.5 ns and amplitude from 0 to 5 V.Timing precision is 200 ps.The rise time of the shaped square electrical waveform is 383 ps and the fall time is 642 ps.The top flatness of the pulse is 4~5%.The amplitude stability of the pulse is 4~5%(p-p).The AWG has been applied in the high power laser system successfully..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1304 (2005)
The Study on Successive Dislocation Feedback Method of Chaos System
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The successive dislocation feedback(SDF)method is proposed to control chaos system.Controlling principle is introduced,and single-mode laser Lorenz system is taken as a typical example to demonstrate the effectiveness of this method.The characteristic quantity of the nucontrolled and controlled system(phase figure、poweThe successive dislocation feedback(SDF)method is proposed to control chaos system.Controlling principle is introduced,and single-mode laser Lorenz system is taken as a typical example to demonstrate the effectiveness of this method.The characteristic quantity of the nucontrolled and controlled system(phase figure、power spectrums、reconstruction of phase space etc.) is compared with each ather.The numerical simulation results show that the phase figure and reconstruction of phase space in the system can be changed into the periodic states from the chaotic attractor which has self similar structure of infinite embedment and is restricted within terminate phase space,and the periodic numbers of different periodic orbits are 2~n×3~mp(n,m are integers);meanwhile the power spectrums of the system can also be changed from the continuous spectrum into the discrete spectrums with some separation single peaks..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1307 (2005)
Influence of the Input Signal and Noise on Characteristic of Stochastic Resonance in a Single-mode Laser System
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Using the linear approximation method,the signal-to-noise ration of the output intensity for a loss-noise model of a single-mode laser driven by the colored pump noise and the quantum noise with cross-correlation between the real and imaginary parts have been calculated,when the laser system input an additive periodicaUsing the linear approximation method,the signal-to-noise ration of the output intensity for a loss-noise model of a single-mode laser driven by the colored pump noise and the quantum noise with cross-correlation between the real and imaginary parts have been calculated,when the laser system input an additive periodically signal,and detected the phenomenon of stochastic resonance in the laser system by virtue of the curve of signal-to-noise versus cross-correlation coefficient between the real and imaginary parts of the quantum noise.Moreover,when the pump noise self-correlation time is very short,with the increase of the amplitude and frequency of the signal,and pump noise self-correlation time,the stochastic resonance in the laser system will enhance,but with the increase of the noises intensity the resonance will decrease.When the pump noise self-correlation time is very long,with the increase of the amplitude of signal and quantum noise intensity,the stochastic resonance in the laser system will enhance,b.
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1311 (2005)
Fabrication of Mid-Infrared 8-Channel Micro Integrated Filter
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Integration is the trend of multi-channel filter in imaging spectrum system,which is called mirco filters.Adjusting the center layer of F-P filter is an effective method to fabricate multi-channel filters.Because of limitation of usual optical coating technology,so the yield of integrating all channel in single substraIntegration is the trend of multi-channel filter in imaging spectrum system,which is called mirco filters.Adjusting the center layer of F-P filter is an effective method to fabricate multi-channel filters.Because of limitation of usual optical coating technology,so the yield of integrating all channel in single substrate is very low.A new method is developed to solve this problem,which combines multi-time ion mask etching with tradition coating technique.As an example,an 8-channel micro integrated filter is fabricated,and optical channel position control accuracy is below 1%..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1316 (2005)
Study on Kerr-Effect-Induced Bias Reduction Method for Resonator Fiber Optic Gyroscope
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The influence of Kerr effect to close-loop digital resonator fiber optic gyroscope based on square-wave frequency modulation was analyzed in theory.The results show that the Kerr-effect-induced bias relates to the light intensity difference between two inverse lightwaves,and the amplitudes of square-wave frequency moduThe influence of Kerr effect to close-loop digital resonator fiber optic gyroscope based on square-wave frequency modulation was analyzed in theory.The results show that the Kerr-effect-induced bias relates to the light intensity difference between two inverse lightwaves,and the amplitudes of square-wave frequency modulation of these inverse lightwaves also affect it.Through proper adjustment to frequency modulation amplitude,the Kerr-effect-induced bias can be effectively reduced.This method for Kerr-effect-induced bias reduction utilizing the characteristic of square-wave frequency modulation,need without any additional optical devices,has low intensity modulation frequency requirement.And it is a effective method for Kerr-effect-induced bias reduction in close-loop digital R-FOG..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1320 (2005)
The Improvement on PGC Demodulation Method Based on Optical Fiber Interferometer Sensors
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An improved phase generated carrier(PGC) demodulation method based on optical fiber interferometer sensors was brought forward.Through improvement on the PGC algorithm and adding frequency overlapped-resistable filter to the system,the result of the demodulation system has been great improved.At the same time,the samplAn improved phase generated carrier(PGC) demodulation method based on optical fiber interferometer sensors was brought forward.Through improvement on the PGC algorithm and adding frequency overlapped-resistable filter to the system,the result of the demodulation system has been great improved.At the same time,the sample rate of the system has get great reduced.The conclusion is very useful in designing the demodulation systems based on optical fiber interferometer sensors..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1324 (2005)
Study on the Technique of Brillouin Scattering Distributed Optical Fiber Sensing Based on Hilbert transform
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The scattering optical signal of BOTDR based on Brillouin scattering distributed sensor is very weak and have a frequency width of several decades megahertz,so it is hard to perform the traditional coherent demodulation.A optical heterodyne detection based on Hilbert transform is presented here.In detail,Brillouin backThe scattering optical signal of BOTDR based on Brillouin scattering distributed sensor is very weak and have a frequency width of several decades megahertz,so it is hard to perform the traditional coherent demodulation.A optical heterodyne detection based on Hilbert transform is presented here.In detail,Brillouin back-scattering light is heterodyne detected with the reference right which is modulated by microwave electric optical modulator to produce frequency-adjustable light,then the detected photoelectric signal is demodulated using Hilbert transform.At last the distributed sensing signal with better S/N ratio is gained,which can enhance the performance of the sensor..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1328 (2005)
Study on Property Improyement of Polymer Coated Materiat for Opticalfibre Bragg Gratings by Using nmSiO2
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The principle of property improvement for polymer by using rigid nanometric particles has been presented,and analysis of property-improving mechanism for polymer material by using nmSiO~~2/siloxane(silicone rubber) has been emphasized.Taking solvent gasoline No.120 as dispersing agent,a kind of compounded material has The principle of property improvement for polymer by using rigid nanometric particles has been presented,and analysis of property-improving mechanism for polymer material by using nmSiO_2/siloxane(silicone rubber) has been emphasized.Taking solvent gasoline No.120 as dispersing agent,a kind of compounded material has been made through co-mixing method to obtain nmSiO_2-vinyl siloxane with addition of hydrogen-containg siloxane for vulcanizing reaction.The agglomerative structure of the said material has been analyzed and studied by using AJ-Ⅲ_a atom-powered microscope,and its mechanical property has been tested.Results show that the elastic modulus of material has been enhanced by 15.4%,the tensile strength increased by 19.4%,and the specific elongation of breaking increased by 30%after improving property with siloxane rubber.Adopting property-improved siloxane polymer material to coat the optical fibre Bragg grating pressure sensor,the coupling behavior between coated material and optical fibre Bragg grating.
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1332 (2005)
Endmember Determination in Hyperspectral Data
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The analysis of hyperspectral data using linear unmixing requires the determination of endmembers consisting in hyperspectral data.All endmember determination methods at present need complex calculation and can not be proved universal for all the hyperspectral data.According to the effective analysis of the informationThe analysis of hyperspectral data using linear unmixing requires the determination of endmembers consisting in hyperspectral data.All endmember determination methods at present need complex calculation and can not be proved universal for all the hyperspectral data.According to the effective analysis of the information presented in hyperspectral data,a new method based on feature space analysis and spectral correlation mapping(FSASCM) was proposed.The method mentioned is simple and universal for almost all the hyperspectral data..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1336 (2005)
Enhanced Emission From Eu3+ in B Ions Doped Sol-gel SiO2 Phosphors
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Eu single doped and Eu,B co-doped SiO~~2 xerogels and films were prepared by sol-gel process,using tetraethoxy silane,boric acid and aluminium nitrate as precursors,europium nitrate as the dopant.The influence of B ions and annealing temperature on luminescent properties of phosphors has been studied using fluorescenceEu single doped and Eu,B co-doped SiO_2 xerogels and films were prepared by sol-gel process,using tetraethoxy silane,boric acid and aluminium nitrate as precursors,europium nitrate as the dopant.The influence of B ions and annealing temperature on luminescent properties of phosphors has been studied using fluorescence spectrum,X-ray diffraction and IR spectrum.The phosphors showed prominent luminescent in red.When heated up to 500℃,the emission spectrum showed six characteristic emission peaks,due to the electronic transition of ~5D_0→~7F_J(J=0,1,2,3,4)for Eu~(3+) respectively and the electronic transition of ~5D_0→~7F_1 was splited two peaks.When B ions were introduced to the Eu doped samples,the red Eu~(3+) emission was enhanced remarkably.This is because Si-O-B bonds were formed in the luminescent materials,and the symmetry of network was breached.Annealing changed the network structure and reduced the content of-OH and water,which benefits intensity of emission from Eu~(3+).The intensity of emission from.
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1340 (2005)
Analysis and Near-lossless Compression Based on CPLD of Interference Hyperspectral Image
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After introducing the interferometer scheme and calculating and analyzing correlation coefficients of interference hyspectral images,a method of Near-lossless Compression based on part DPCM for interference hyspectral image is proposed.Complex programmable logic device(CPLD)has been chosen as the hardware design platfoAfter introducing the interferometer scheme and calculating and analyzing correlation coefficients of interference hyspectral images,a method of Near-lossless Compression based on part DPCM for interference hyspectral image is proposed.Complex programmable logic device(CPLD)has been chosen as the hardware design platform,and the algorithm has been described with VHDL.The designed algorithm has been successfully fulfilled system simulation with Maxplus Ⅱ software.The simulation result shows that the algorithm is simple and feasible and can be realized with hardware..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1346 (2005)
Optical Design of a Flat Field Unobstructed Two-mirror System with Wide Field of View
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Based on aberration theory,the design idea of flat field unobstructed two-mirror system is presented.In this system,spherical aberration,coma,astigmatism and field curvature are free.Designing method and process is described and characteristic of system is summarized.Two systems are designed with the field of view of 6Based on aberration theory,the design idea of flat field unobstructed two-mirror system is presented.In this system,spherical aberration,coma,astigmatism and field curvature are free.Designing method and process is described and characteristic of system is summarized.Two systems are designed with the field of view of 6°×6° and 20°×1° and the image quality is in limit of diffraction.The configuration is simple and alignment is convenient.This system is very valuable for space sensing field..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1351 (2005)
Analysis on Increment of Index of Glass and Increment of Secondary Spectrum of the Wide Bands FT Lens
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The effect induced by the increment of refraction index and dispersion of glass in the wide bands FT(Fourier Translate) lens were introduced.The formula of the increment of secondary spectrum which brought by the increment of refraction index and dispersion of glass were deduced.The increment of secondary spectrum of tThe effect induced by the increment of refraction index and dispersion of glass in the wide bands FT(Fourier Translate) lens were introduced.The formula of the increment of secondary spectrum which brought by the increment of refraction index and dispersion of glass were deduced.The increment of secondary spectrum of thin double lens in wide bands system was emphatically discussed.In this thesis,the coefficient of the increment to secondary spectrum is 0.28,which is said this increment is about 28% of the theory secondary spectrum of thin double lens,so it should not be ignored by any designer.The example showed in this thesis indicated that the increment of refraction index and dispersion of glass in the wide bands system had more serious effect to its imaging quality.In addition,the FT lens wavefront aberrations were mentioned,and the wavefront aberrations were designed less than 1/10 waves in the using bands.When the best glasses couple were used to produce the FT lens,the wavefront aberration could be rem.
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1355 (2005)
Fractional Correlation Properties of the Joint Fractional Fourier Transform Correlator
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The mathematical expressions of the joint fractional Fourier transform correlator(JFRTC) are demonstrated,according to which,the properties of the JFRTC are discussed.It is shown that the properties of a JFRTC are different from that of a conventional JTC.In a conventional JTC,the distance between the two desired correThe mathematical expressions of the joint fractional Fourier transform correlator(JFRTC) are demonstrated,according to which,the properties of the JFRTC are discussed.It is shown that the properties of a JFRTC are different from that of a conventional JTC.In a conventional JTC,the distance between the two desired correlation signals at the output plane is fixed and is depended on the distance between the target and the reference images.However,by shifting the fractional orders,the distance between the two desired correlation signals at the output plane of a JFRTC can be changed larger or smaller than that of a conventional JTC.Besides,when the fractional order is shifted appropriately,the distortion of the fractional spectrum derived from the dimension distortion of the target image can be offset.Thus the JFRTC is predicted having the capability of distortion-invariant pattern recognition.On the other hand,the intensity of the desired correlation signals at the output plane of a JFRTC is always lower than tha.
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1367 (2005)
Pulsed Laser Induced Damage Model of Optical Coatings with Absorbing Inclusion
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Pulsed laser damage model of optical coatings with absorbing inclusion was investigated.The case for absorbing inclusion thermal model was derived from the thermal conduction equations and the heat transfer from the absorbing defects to the host coatings materials was considered.The absorption cross section of the inclPulsed laser damage model of optical coatings with absorbing inclusion was investigated.The case for absorbing inclusion thermal model was derived from the thermal conduction equations and the heat transfer from the absorbing defects to the host coatings materials was considered.The absorption cross section of the inclusion was simplified by introducing scattering coefficient.The model was used to simulate the damage onset and the damage expanding process.ZrO_2∶Y2O_3 monolayer was prepared by Electron Beam Evaporation(EBE),and laser damage testing was performed.The typical damage was defects-initiated.The main impurity element was platinum from the Glow Discharge Mass Spectrometer(GDMS) analysis,and the content of it was about 0.9%.The numerical simulation result of laser damage was found to agree well with experimental data..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1372 (2005)
GdFeCo/TbFeCo Films for Magnetic Super Resolution Magneto-optical Recording
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rs(GdFeCo/TbFeCo) were prepared by sputtering method.The magnetization transition caused by temperature changes has been investigated by the hysteresis loops and the Kerr rotation hysteresis loops.The results indicate that the magnetization direction of readout layer changes from in-plane to perpendicular with temperatrs(GdFeCo/TbFeCo) were prepared by sputtering method.The magnetization transition caused by temperature changes has been investigated by the hysteresis loops and the Kerr rotation hysteresis loops.The results indicate that the magnetization direction of readout layer changes from in-plane to perpendicular with temperature increaseing.The films have the basic properties of the CAD-MSR disks.The transition occurs mainly as a result of the changes in the saturation magnetization.When the temperature is increased to the compensation temperature,the saturation magnetization and the demagnetizing energy of the GdFeCo layer decrease,with the exchange-coupled interaction,the magnetization direction of readout layer changes from in-plane to perpendicular.Magneto-optical recording;Magnet.
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1376 (2005)
Statistical analysis of Cascaded PLC-based PMD Compensator with PDL
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By utilizing Müller matrix approach,a detailed statistical analysis on the PDL(polarization dependent loss) dependence of differential group delay(DGD) in cascaded planar lightwave circuit(PLC) based PMD compensator is presented.For PDL values ranging from 0 to 10 dB,the DGD distributions were calculated with MontBy utilizing Müller matrix approach,a detailed statistical analysis on the PDL(polarization dependent loss) dependence of differential group delay(DGD) in cascaded planar lightwave circuit(PLC) based PMD compensator is presented.For PDL values ranging from 0 to 10 dB,the DGD distributions were calculated with Monte Carlo simulation for cascaded PLC circuits of 3,4,5 and 15 segments.Based on comparison with Maxwell distribution,it was found that an optimized segment number for cascaded PLC circuit with PDL is around 4,and that DGD distribution exhibits a severe deviation away from the Maxwellian as PDL is above 8 dB..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1380 (2005)
Numerical Simulation on Gain and Noise Characteristic of High Concentration Tellurite-based EDFA
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Numerical simulation on high concentration tellurite EDFA is based on four energy-level model.The main characteristic of gain and noise figure both in C-band and L-band is presented.The bandwidth achieves 85 nm when gain of amplifier both in C-band and L-band achieves above 20 dB.Furthermore,the degradation of gain andNumerical simulation on high concentration tellurite EDFA is based on four energy-level model.The main characteristic of gain and noise figure both in C-band and L-band is presented.The bandwidth achieves 85 nm when gain of amplifier both in C-band and L-band achieves above 20 dB.Furthermore,the degradation of gain and noise characteristic caused by the effect of upconversion which is brought by high concentration is analyzed.The degradation is 4% in C-band and 10% in L-band.The degradation is decreasing when the pump power increasing.It is just 0.1% when the two-stage amplifier is bi-directional pumped..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1385 (2005)
Research on the Propagation of Femetosecond Optical Solitons Under the Perturbation of Continuous Wave
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Perturbed higher order nonlinear Schrdinger equation describing the propagation of femetosecond optical pulse in the optical fiber under the perturbation of continuous wave was presented.The interactions between bright optical soliton and continuous wave have been studied by moment method and perturbation theory.Also Perturbed higher order nonlinear Schrdinger equation describing the propagation of femetosecond optical pulse in the optical fiber under the perturbation of continuous wave was presented.The interactions between bright optical soliton and continuous wave have been studied by moment method and perturbation theory.Also the numerical evolution by Runge-Kutta and split step Fourier method are given.As a conclusion,the injected continuous wave should be avoided at best since it was harmful to the optical soliton communication..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1389 (2005)
Investigation on All-Optical Clock Recovery from RZ-Format Data at 64Gbit/s by Using a Two-Section Index-Coupled DFB Laser
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High speed all-optical clock recovery from 64Gbit/s RZ-format PRBS data by using atwo-section index-coupled distributed feedback (DFB) laser is simulated and demonstrated. Theperformance of it such as timing jitter, lockup time, locking range are described and analyzed indetail.High speed all-optical clock recovery from 64Gbit/s RZ-format PRBS data by using atwo-section index-coupled distributed feedback (DFB) laser is simulated and demonstrated. Theperformance of it such as timing jitter, lockup time, locking range are described and analyzed indetail..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1393 (2005)
A Fast Optimal Design Method for Broadband Raman Amplifiers
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An improved Simulated Annealing(ISA) method for fast optimizing distributed multi-pump Raman amplifier(DMRA) was presented.A simple algorithm for counter-pumped DMRA was derived through reasonable approximations.The proposed ISA can effectively solve the multimodal optimization including the global and local optima in An improved Simulated Annealing(ISA) method for fast optimizing distributed multi-pump Raman amplifier(DMRA) was presented.A simple algorithm for counter-pumped DMRA was derived through reasonable approximations.The proposed ISA can effectively solve the multimodal optimization including the global and local optima in the DMRA.Optimization results show that,under the conditions of the ON-OFF gain of 10 dB,the relative gain flatness of <0.12 and the fiber haul of 80 km,amplifier bandwidths at larger 80 nm have been achieved with 4,5 and 6 pumps by using the optimization of the ISA.Comparing with other existing methods,the ISA method can attain a required low gain ripples and larger bandwidth with less pumps..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1397 (2005)
Application of Homomorphic Technologyin in Infrared Images Processing
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In order to improve the contrast of infrared image,a method of homomorphic filtering for image enhancement is proposed.By use of the method,the influences of noises are reduced and the contrast and quality of original images improved.A good foundation is built in order to collect the characteristic information in the iIn order to improve the contrast of infrared image,a method of homomorphic filtering for image enhancement is proposed.By use of the method,the influences of noises are reduced and the contrast and quality of original images improved.A good foundation is built in order to collect the characteristic information in the images further.The computer simulation and experiment results show that homomorphic filtering is an efficient method for contrast enhancement of infrared images..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1401 (2005)
An Automatic Location Algorithm for Low SNR Moving Targets Based on Adaptive Template
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SNR is used to analyze target gray characters to its neighbor pixels. According to these low SNR moving puny targets, an adaptive template matching method has been proposed to extract these targets by part Hausdorff distance in measuring the similarity between the templates and target images. Then combined with adaptivSNR is used to analyze target gray characters to its neighbor pixels. According to these low SNR moving puny targets, an adaptive template matching method has been proposed to extract these targets by part Hausdorff distance in measuring the similarity between the templates and target images. Then combined with adaptive thresholding technique, targets precision pixel dimensions can be calculated in given pictures. Critical experiments results of different target images sequences show that this algorithm is fast, stable and flexible with much reference value in related Automatic Target Recognition and location fields..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1404 (2005)
An Algorithm of Multi-resolution Steps Image Partition Based on Strong Edge Blocks
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According to the detection of changes in image sequences,an algorithm of multi-resolution steps image partition based on strong edge blocks is proposed in this papers.Firstly,the histogram is computed from the strong edge blocks in the image sequences.Then,different images are compared by algorithm of multi-resolution According to the detection of changes in image sequences,an algorithm of multi-resolution steps image partition based on strong edge blocks is proposed in this papers.Firstly,the histogram is computed from the strong edge blocks in the image sequences.Then,different images are compared by algorithm of multi-resolution steps.This method can not only further detect the changes of image,but also judge the types of changing images.In the process of selecting thresholds,the adaptive thresholds are used.The experimental results show that this method is promising..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1408 (2005)
Selection of Regularization Parameter for Anisotropic Diffusion Filtering
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The selection of regularization parameter for anisotropic diffusion in image processing is discussed.An approach of noise estimation based piecewise constant image model is proposed.In this approach,image noise is estimated by minimal variance of region in image.And then the relation between regularization parameter anThe selection of regularization parameter for anisotropic diffusion in image processing is discussed.An approach of noise estimation based piecewise constant image model is proposed.In this approach,image noise is estimated by minimal variance of region in image.And then the relation between regularization parameter and image noise is analyzed.A modified formula between regularization parameter and image noise is suggested.According to this formula,regularization parameter is adapted to image noise.Finally,the rule to select size of gauss mask to regularization parameter is given.Resutt shows that anisotropic diffusion have good adaptability to image noise with the selection of regularization parameter..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1411 (2005)
Camera Calibration Based on Image Series
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A practicable method of determining the camera′s intrinsic parameters(with 5 parameters) as well as its extrinsic parameters is proposed.All the camera parameters are determined based on the walking humans and their shadows and the method is linearly.Meanwhile the relationship of the corresponding points have not to beA practicable method of determining the camera′s intrinsic parameters(with 5 parameters) as well as its extrinsic parameters is proposed.All the camera parameters are determined based on the walking humans and their shadows and the method is linearly.Meanwhile the relationship of the corresponding points have not to be considered,so the speed of calibration could be increased greatly.Extensive simulations and experimental results with real images show that this proposed method is both accurate and robust.This method can be used in on-line system..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1415 (2005)
Image Enhancement Based on
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Since forward and backward diffusion cannot hold flow-like edges,and coherence enhancement diffusion cannot sharpen edges,a new edge-directed nonlinear diffusion equation to enhance image is put forward.The new model introduces forward and backward diffusion to the tensor diffusion,and gets a new diffusivity,which combSince forward and backward diffusion cannot hold flow-like edges,and coherence enhancement diffusion cannot sharpen edges,a new edge-directed nonlinear diffusion equation to enhance image is put forward.The new model introduces forward and backward diffusion to the tensor diffusion,and gets a new diffusivity,which combines the merits of these two methods.The new model adapts an operator like coherence enhancement diffusion for edge orientation,and defines eigenvalues based on edge′s orientation such that the new tensor has positive diffusion coefficient in edge direction and negative diffusion coefficient in gradient direction.Both theory analysis and numerical results show that the new model has better enhancement result than coherence enhancing diffusion and forward and backward diffusion..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1420 (2005)
Face Recognition Using Neural Network Based on Continuous Wavelet Transform
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A face recognition method using neural network is proposed based on continuous wavelet transform.The theory of wavelet analysis is introduced.The method of selecting mother wavelet function is detailed according wavelet transform norm,and the number of wavelet knot and the initialization are decided by wavelet ridge.ThA face recognition method using neural network is proposed based on continuous wavelet transform.The theory of wavelet analysis is introduced.The method of selecting mother wavelet function is detailed according wavelet transform norm,and the number of wavelet knot and the initialization are decided by wavelet ridge.The training method of parameters is also introduced.Through continuous wavelet analysis and self-organizing and self-training of neural networks,the connection weights and the parameters of scales and positions are adapted to complete the task of face recognition........
Acta Photonica Sinica
- Publication Date: Jun. 12, 2006
- Vol. 34, Issue 9, 1425 (2005)
A Study on the Multiplication Technique of Nano-moiré Fringe
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A nano-moiré fringe multiplication method is proposed and used to measure nano-deformation of single crystal materials.The lattice structure of single crystal materials is captured by TEM(Transmission Electron Microscope) and acted as a specimen grating.An unidirectional grating fabricated on glass or film is seleA nano-moiré fringe multiplication method is proposed and used to measure nano-deformation of single crystal materials.The lattice structure of single crystal materials is captured by TEM(Transmission Electron Microscope) and acted as a specimen grating.An unidirectional grating fabricated on glass or film is selected as a reference grating.The formation principles of TEM nano-moiré fringe,the relationship between TEM magnification and grating frequency,as well as displacement and strain measurement method .......
Acta Photonica Sinica
- Publication Date: Jun. 12, 2006
- Vol. 34, Issue 9, 1431 (2005)
Research on Un-illuminant Space Target Visual Detection Technique
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In space targets,about 7% of them are manmade satellites;others are space relics or debris.Only rely on sun shining can these targets be detected because all of them do not illuminant themselves.They are so far from the sensor that can be considered as point targets.Mathematics model of un-illuminant space target is seIn space targets,about 7% of them are manmade satellites;others are space relics or debris.Only rely on sun shining can these targets be detected because all of them do not illuminant themselves.They are so far from the sensor that can be considered as point targets.Mathematics model of un-illuminant space target is set up.Based on classical optical theory the relationships between brightness and dimension and surface characteristic and view angle and distance are analyzed;and the relationships between detection ability of optical sensor and parameters of optics and exposal time are demonstrated based on energy conservation law. In the end the correctness of the model and formula are proved by test, so it can provide reference to optical system design used in space un-illuminant targets detection..
Acta Photonica Sinica
- Publication Date: Aug. 25, 2021
- Vol. 34, Issue 9, 1438 (2005)
Optoelectronics
A Model for 1/f Noise in Optoelectronic Coupled Devices
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Flicker noise(1/f noise) in Optoelectronic Coupled Devices(OCDs) is studied over a wide range of bias currents with special emphasis on the influence of electrical stress.Experimental results demonstrate that there is a similar rule for OCDs before and after stressed,and the magnitude of 1/f noise is proportional to thFlicker noise(1/f noise) in Optoelectronic Coupled Devices(OCDs) is studied over a wide range of bias currents with special emphasis on the influence of electrical stress.Experimental results demonstrate that there is a similar rule for OCDs before and after stressed,and the magnitude of 1/f noise is proportional to the bias current in the range of low currents and proportional to the power of the bias current in the rang of high currents.Comparing to virgin device,the magnitude of 1/f noise in the stressed device increases about 7 times.It is discussed that 1/f noise belongs to diffusion 1/f noise in the rang of low currents,while,at high currents,it belongs to recombination 1/f noise,and the increasing magnitude of 1/f noise is due to new traps induced by electrical stress.Based on the mechanisms of carrier numbers fluctuations and carrier relocity fluctuations,a 1/f noise model in OCDs is developed.Experimental results agree well with the developed model..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1359 (2005)
The Study of InAsxSb1-x on GaSb Substrate Grown by LP-MOCVD
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InAsSb epitaxy had been obtained on(100) GaSb substrate by a home-made low pressure MOCVD system.The characteristic of InAsSb epitaxy was investigated by means of x-ray diffraction technique,optical microscopy and scanning electron microscopy(SEM),and electron microprobe analysis(SEM).And the dependence of surface morpInAsSb epitaxy had been obtained on(100) GaSb substrate by a home-made low pressure MOCVD system.The characteristic of InAsSb epitaxy was investigated by means of x-ray diffraction technique,optical microscopy and scanning electron microscopy(SEM),and electron microprobe analysis(SEM).And the dependence of surface morphology and solid composition of epitaxy on growth temperature,Ⅴ/Ⅲ ratio and buffer layer is studied.High quality mirror-like surfaces with a minimum lattice mismatch was obtained..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2005
- Vol. 34, Issue 9, 1363 (2005)
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