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2005
Volume: 34 Issue 1
40 Article(s)
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Research Article
Theoretical Study on the Butt-coupling of Semiconductor Laser and Fiber Bragg Grating
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The butt-coupling between a semiconductor laser diode and a fiber Bragg grating external cavity acts a key roll on the laser characteristics. The scatter matrix method considering the butt-coupling efficiency is used to analyze the butt-coupling between them. It is found that the butt-coupling distance and coupling effThe butt-coupling between a semiconductor laser diode and a fiber Bragg grating external cavity acts a key roll on the laser characteristics. The scatter matrix method considering the butt-coupling efficiency is used to analyze the butt-coupling between them. It is found that the butt-coupling distance and coupling efficiency determine the laser characteristics. For strong feedback, the single lasing wavelength changes in the reflection bandwidth of the effective reflectivity (approximately the Bragg region of the fiber Bragg grating) as the distances change. For weak feedback condition, some different results are obtained. The SMSRs in the two conditions are presented and analyzed. These results can provide important design guidance of device parameters for the practical fabrication..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 1 (2005)
Multi-wavelength Erbium-doped Superfluorescent Fiber Source with High Power,High Efficiency and High Extinction
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Based on an erbium-doped double pass backward (DPB) superfluorescent fiber source (SFS), by employing a improved Mach-zehnder interferometer filter (MZI) as spectrum slicing and spectrum pre-slicing component, respectively, two multi-wavelength superfluorescent fiber sources (MW SFSs) with channel spacing of ～0.8 nm arBased on an erbium-doped double pass backward (DPB) superfluorescent fiber source (SFS), by employing a improved Mach-zehnder interferometer filter (MZI) as spectrum slicing and spectrum pre-slicing component, respectively, two multi-wavelength superfluorescent fiber sources (MW SFSs) with channel spacing of ～0.8 nm are got. For the 20 channels around 1550 nm (from 1542 to 1559 nm), the power fluctuations are less than 0.5 dB. The extinction of the former is as high as 27 dB, and the latter is ～18dB. With the latter schematic, output power as high as 25.3 mW with pump efficiency of 34.8% is achieved under a limited 980 nm pump power of 72.8 mW. By changing the difference of the arms of the Mach-Zehnder interferometer filter, 50 channels around 1550 nm with spacing of ～0.4 nm are got, and the extinction is ～16 dB..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 6 (2005)
Passive Q-switched Modelocking Diode-end-pumped Yb∶YAG with Surface-state Type of Semiconductor Saturable Absorption Mirror
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A new type of surface-state semiconductor saturable absorption mirror was introduced, with which passive Q-switched modelocking of diode-end-pumped Yb∶ YAG laser was realized. At the 1.4 W of pumping power, Q-switched modelocking seires was obtained, which has 1 mW average output and 200 MHz frequency.A new type of surface-state semiconductor saturable absorption mirror was introduced, with which passive Q-switched modelocking of diode-end-pumped Yb∶ YAG laser was realized. At the 1.4 W of pumping power, Q-switched modelocking seires was obtained, which has 1 mW average output and 200 MHz frequency..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 11 (2005)
HHG of 795nm Ti∶sapphire Femtosecond laser in Ar by Using Static Gas Target
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High-order harmonics of 120 fs/795 nm Ti∶sapphire laser in Ar in static gas target are reported. Compared with the traditional gas target, static gas target is simple in experimental configuration and experimental parameters can be easily controlled. Changes of high-order harmonic intensities vs gas pressures are obserHigh-order harmonics of 120 fs/795 nm Ti∶sapphire laser in Ar in static gas target are reported. Compared with the traditional gas target, static gas target is simple in experimental configuration and experimental parameters can be easily controlled. Changes of high-order harmonic intensities vs gas pressures are observed with 42 mJ and 7.5 mJ linearly-polarized laser..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 14 (2005)
Effect of Absorption on the Optical Characteristics of VCSELs
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The effect of absorption in DBR and fused interface on the optical characteristics of vertical-cavity surface-emitting lasers (VCSELs) has been analysed in detail by using optical transfer matrix method. The result shows that the absorption in DBR and fused interface has significant influence on both the reflectivity aThe effect of absorption in DBR and fused interface on the optical characteristics of vertical-cavity surface-emitting lasers (VCSELs) has been analysed in detail by using optical transfer matrix method. The result shows that the absorption in DBR and fused interface has significant influence on both the reflectivity and the potential transmittivity of the DBR and the VCSEL, but has a weak effect on the phase change on reflection of the DBR at center wavelength and the mode phase change on reflection and mode position of the VCSEL.With the increase of the absorption in DBR and fused interface,the reflectivity of DBR at center wavelength decreases gradually,and the mode reflectivity of VCSEL decreases greatly to a minimum and then increases gradually,and the potential transmittivity of DBR at center wavelength and of VCSEL at mode wavelength reduce greatly respectively.Moreover, it is beneficial to increase the optical output efficiency of VCSELs to put the fused interface a little far away from the active reg.
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 18 (2005)
Scattering Characteristics and Targets Recognition of Laser TDD
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Based on the 3D coordinates of target facet primitives and flying-time of laser pulse, a novel method is presented here to describe the scattering characteristics of Laser Target Detection Device. The scattering power equations of target and aerosol are derived theoretically, as well as the simulating pulses wave of reBased on the 3D coordinates of target facet primitives and flying-time of laser pulse, a novel method is presented here to describe the scattering characteristics of Laser Target Detection Device. The scattering power equations of target and aerosol are derived theoretically, as well as the simulating pulses wave of receiving signal is given. According to the amplitude-width information of pulse, a recognition method of discriminating target and disturbing signals is shown..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 22 (2005)
Fabrication of 808 nm SQW Semiconductor Laser Facet AR HR Coating
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HfO 2/SiO 2 front and back facet coatings of 808 nm SQW semiconductor laser has been fabricated with Plasma Assisted Electron Beem Deposition (Plasma-Ion Assisted Deposition) method.Front AR coating reflectivity is as low as 12.2% and back HR coating is as high as 97.9%.The output power is improved 79%,external differeHfO 2/SiO 2 front and back facet coatings of 808 nm SQW semiconductor laser has been fabricated with Plasma Assisted Electron Beem Deposition (Plasma-Ion Assisted Deposition) method.Front AR coating reflectivity is as low as 12.2% and back HR coating is as high as 97.9%.The output power is improved 79%,external different quantum efficiency improved 80%.The output efficiency increased from 22.2% to 39.8% for 100 μm wide 1000 μm-cavity length device..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 25 (2005)
Continuous-wave Quasi-phase-matched Second Harmonic Generationat 490 nm in Periodically Poled MgO:LiNbO3
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A first order quasi-phase-matched periodically poled micro-structure MgO∶LiNbO 3 for SHG with 4.8～5.2 μm period, 20 mm length, 18 mm width and 1 mm thickness has been successfully fabricated by applying an external field at room temperature. Because the switching field of MgO∶LiNbO 3 is ～5.5 kV/mm, which is approximateA first order quasi-phase-matched periodically poled micro-structure MgO∶LiNbO 3 for SHG with 4.8～5.2 μm period, 20 mm length, 18 mm width and 1 mm thickness has been successfully fabricated by applying an external field at room temperature. Because the switching field of MgO∶LiNbO 3 is ～5.5 kV/mm, which is approximately one fourth that of the conventional congruent field, periodic poling of thicker MgO∶LiNbO 3 substrates was successfully performed by means of an electric field poling process at room temperature. Using the sample to double the frequency of a diode laser at 980 nm was studied. About 40 mW of CW 490 nm blue light was obtained pumped by 800 mW of the fundamental power, which corresponds to 5% power conversion efficiency. No obvious optical damage has been observed..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 29 (2005)
Influence of Stimulated Raman Scattering on Modulation Instability in Single-mode Fibers
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Modulation instability (MI) in single-mode optical fibers is investigated analytically and numerically using a modified nonlinear Schrdinger equation. Due to the role of stimulated Raman scattering, Raman gain spectrum is superposed over the conventional MI gain spectrum in optical fibers. As a result, MI occurs in thModulation instability (MI) in single-mode optical fibers is investigated analytically and numerically using a modified nonlinear Schrdinger equation. Due to the role of stimulated Raman scattering, Raman gain spectrum is superposed over the conventional MI gain spectrum in optical fibers. As a result, MI occurs in the normal dispersion region where MI does not appear otherwise; in the anomalous dispersion region, as initial power increases, the spectral range and gain of the conventional MI gain spectrum increase, while the spectral range of the Raman gain spectrum remains unchanged even though its gain increases. Thus the conventional instability region gradually intrudes and eventually screens Raman gain region. Numerical simulations confirms the analytical results and demonstrates that ultrashort pulse trains can be generated by MI in the anomalous dispersion regime, but Raman soliton self-frequency shift appears as the pulse train propagates further..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 32 (2005)
Phase-shifted Long-period Fiber Grating Written by High-frequency CO2 Laser Pulses
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The spectrum of phase-shifted long-period fiber grating is analyzed by the coupled-mode theory and transfer-matrix method. Then under the guidance of this analysis, it is for the first time that the phase-shifted long-period fiber grating is fabricated successfully by using high-frequency CO 2 laser pulses. During the The spectrum of phase-shifted long-period fiber grating is analyzed by the coupled-mode theory and transfer-matrix method. Then under the guidance of this analysis, it is for the first time that the phase-shifted long-period fiber grating is fabricated successfully by using high-frequency CO 2 laser pulses. During the process of fabrication, computer is used to draw the structural graph of the gratings and to control the power and time of laser pulses exposed on the optical fiber. In such a way, the gratings are made automatically. The grating made actually shows the phase-shifted spectrum during the scale of 1520～1570 nm and 1610～1670 nm. The temperature response of the latter is tested, and the result shows that the center wavelengths of the one pass band and the two loss bands have the same index: 0.064 nm/℃.What′s more, the strain response of the PSLPG is measured, and the result shows that the index is -0.51 nm/mε. So in the sensing field, it is viable to test the centre wavelength of the pass band to m.
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 38 (2005)
Influence of Light Sport at End-face of Optical Fibers to Powers of Axis-symmetrical Guided Modes in Step-index Optical Fibers
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The formula of transmitted power of axis-symmetrical modes is obtained from the integrate solution of wave equations. It contains the influence of the incident light and can be used to compare the powers of different modes. Simulating a practical light spot on the end-face of an optical fiber with a Gaussian-spot, the The formula of transmitted power of axis-symmetrical modes is obtained from the integrate solution of wave equations. It contains the influence of the incident light and can be used to compare the powers of different modes. Simulating a practical light spot on the end-face of an optical fiber with a Gaussian-spot, the influences of focus situation on power distribution among different modes are discussed. It is shown that by adjusting frequency and focusing situation properly, some modes can be enhanced and others can be restrained..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 41 (2005)
Distortion Detect of Large Field Projection Lithography Lens
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Distortion is the key index of lithography lens system, but there is no much reports about it. This paper presents a new theory and system about distortion detect, and a new method about how to process the detected data. A new 6-inch dimension, 3 μm resolution large field projection lithography lens was detected with tDistortion is the key index of lithography lens system, but there is no much reports about it. This paper presents a new theory and system about distortion detect, and a new method about how to process the detected data. A new 6-inch dimension, 3 μm resolution large field projection lithography lens was detected with this system and the results is that the distortion of this lithography lens is less than 2.0 μm in all field..
Acta Photonica Sinica
- Publication Date: Jun. 12, 2006
- Vol. 34, Issue 1, 46 (2005)
Optical System Design for a Dual-band Space Imaging Spectrometer
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Optical features of optical system of a dual-band imaging spectrometer is analyzed.Based on the mutual compensation of optical materials focal plane shift constant, the equations are formulated for athermalization of optical system. A design example of a three lenses optical system with two materials operating in the 3Optical features of optical system of a dual-band imaging spectrometer is analyzed.Based on the mutual compensation of optical materials focal plane shift constant, the equations are formulated for athermalization of optical system. A design example of a three lenses optical system with two materials operating in the 3～5 μm and 8～11 μm wavelength bands with 100% cold shield efficiency, 10° field of view, 100 mm focal length, 1.98 F number is designed, associated with high optical quality in large working temperature range -20～70°C. The defocus, wavefront error and modulation transfer function(MTF) of optical system are analyzed..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 50 (2005)
The Analysis of Relative Illumination for Projection Lens Based on étendue
Based on étendue, relative illumination of projection lens is analyzed. With consideration of the inner intensity distribution and angular distribution of light source, the intensity distribution vs étendue of facular emitted from lamp together with reflector has been deduced. Moreover, the intensity vs angulBased on étendue, relative illumination of projection lens is analyzed. With consideration of the inner intensity distribution and angular distribution of light source, the intensity distribution vs étendue of facular emitted from lamp together with reflector has been deduced. Moreover, the intensity vs angular distribution of facular on LCD panel, which is far different away from Lambert distribution, has also been obtained by étendue transfer. Under the analysis, calculation method for relative illumination is revised, and relative illumination of LCD projection lens is calculated. By experiment, the new method based on étendue has more accuracy in relative illumination calculation for LCD projection lens..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 55 (2005)
Adjustive Methods for Image-formation System Adopting X-ray Excitated Glass Scintillator
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In an optical image-formation system with very narrow depth of field,it is impossible to get a very clear image because of the longitudinal distribution of different illuminant plane.The image-formation system adopting X-ray excitated glass scintillator features this character. In glass scintillator,luminous intensity In an optical image-formation system with very narrow depth of field,it is impossible to get a very clear image because of the longitudinal distribution of different illuminant plane.The image-formation system adopting X-ray excitated glass scintillator features this character. In glass scintillator,luminous intensity of different planes decay exponentially with the depth X-ray penetrate through.In order to get a clear image from such a system,changing law of image definition is simulated in the way of geometrical optics and some very meaningful results are derived.The reasons how to adjust such a system according to the X-ray energy and the width of the glass are also explained.The experimental results according with the simulated image definition are displayed..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 59 (2005)
Binary Optic Dual-band Infrared Imaging Spectrometer
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On the basis of the characteristics of the infrared radiation and binary optical elements, a novel binary optic dual-band infrared imaging spectrometer is described. The design methodology is presented and theoretical formulas are established. A practical example proves proposed method valid and feasible. It shows thatOn the basis of the characteristics of the infrared radiation and binary optical elements, a novel binary optic dual-band infrared imaging spectrometer is described. The design methodology is presented and theoretical formulas are established. A practical example proves proposed method valid and feasible. It shows that the method is useful in designing compact, economical, lightweight dual-band infrared imaging spectrometer..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 63 (2005)
Theoretical Study of the Dispersion Effect of Linear Birefringenceupon the Sensitivity of an Optical Current Sensor
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The dispersion properties of linear birefringence and its effect upon the sensitivity of a bulk-glass optical current sensor are theoretically analyzed taking the Jones′ Matrix as a mathematical tool and simulated with a computer. The peak wavelength of the optical source used in an optical current sensing system will The dispersion properties of linear birefringence and its effect upon the sensitivity of a bulk-glass optical current sensor are theoretically analyzed taking the Jones′ Matrix as a mathematical tool and simulated with a computer. The peak wavelength of the optical source used in an optical current sensing system will be changed by the fluctuations of the driving current or its ambient temperature. This will result in the fluctuation of the sensitivity of the system because of the dispersion of the linear birefringence existing inside the sensing head. The investigation results show that the dispersion will affect the scale factor of the system. But the effect is so small that can be omitted. These results might be useful for the researchers and designers working in the optical current sensing techniques area..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 66 (2005)
A Novel Mach-Zehnder Interferometer-based Sensor with Microbending Structures and Its Optimal Design
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A novel Mach-Zehnder Interferometer (MZI)-based planar waveguide sensor is introduced. The microbending waveguides are used in the two arms of the MZI. The sensitive region and the influence of the microbending shape to the sensitivity of the sensor are studied with three-dimensional beam propagation method. The amplitA novel Mach-Zehnder Interferometer (MZI)-based planar waveguide sensor is introduced. The microbending waveguides are used in the two arms of the MZI. The sensitive region and the influence of the microbending shape to the sensitivity of the sensor are studied with three-dimensional beam propagation method. The amplitude and period of a sin microbending structure are optimized with a gradient-based search algorithm. The sensitivity of the novel sensor is shown to be much better than that of a conventional MZI-based planar waveguide sensor..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 69 (2005)
Analysis for the Effect of Optical Packet Assembly Mechanism on Self-similar Traffic Shaping
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Optical packet assembly at the edge router is expected to serve as a traffic shaper to mitigate the adverse influence of self-similar traffic in optical packet-switched networks. The paper aims to fully explore the effects of optical packet assembly on traffic shaping. Our study by simulation shows that optical packet Optical packet assembly at the edge router is expected to serve as a traffic shaper to mitigate the adverse influence of self-similar traffic in optical packet-switched networks. The paper aims to fully explore the effects of optical packet assembly on traffic shaping. Our study by simulation shows that optical packet assembly performs self-similar traffic shaping not only by significantly reducing of self-similarity, but also by improving the short-term correlation and the marginal distribution of traffic processes..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 73 (2005)
The Applicability Of Initial Chirp Compensating For Fiber Dispersion Function
Taking the transmission of Gauss pulse with initial chirp through Single-mode optical fiber as an example, the theoretical analysis and numerical calculation of the compensation the linear initial chirp having on the second-order and third-order dispersion are made.It is shown that the linear initial chirp has some comTaking the transmission of Gauss pulse with initial chirp through Single-mode optical fiber as an example, the theoretical analysis and numerical calculation of the compensation the linear initial chirp having on the second-order and third-order dispersion are made.It is shown that the linear initial chirp has some compensation to the second-order dispersion (linear dispersion), but that the third-order dispersion can′t be compensated by the initial chirp simply..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 78 (2005)
Optimal Design of Optical Buffer for WWW Service
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The system performance of optical buffing is investigated based on fiber delay lines in asynchronous optical packet-switched networks. The queuing model here is different from other papers in that the interval of optical packet arrival is defined by Weibull distribution, which has been demonstrated to be a suitable traThe system performance of optical buffing is investigated based on fiber delay lines in asynchronous optical packet-switched networks. The queuing model here is different from other papers in that the interval of optical packet arrival is defined by Weibull distribution, which has been demonstrated to be a suitable traffic model for WWW service. Through numerical analysis, conclusions show that the system performance of optical buffering, such as packet loss possibility, the average waiting time, can be optimized by the proper design of the delay unit and the buffering depth for given traffic load..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 82 (2005)
Study of Fiber Bragg Grating Sensor System Based on OFDR/WDM
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Optical frequency domain reflectometry(OFDR) techniques and wavelength division multiplexing(WDM) techniques are applied to interrogating fiber grating array and tunable optical filter (TOF) to modulating multiplex signals. The fundamental principle of OFDR has been analyzed and the space resolution and measurement ranOptical frequency domain reflectometry(OFDR) techniques and wavelength division multiplexing(WDM) techniques are applied to interrogating fiber grating array and tunable optical filter (TOF) to modulating multiplex signals. The fundamental principle of OFDR has been analyzed and the space resolution and measurement range of this system were calculated theoretically and then a sensor network of FBG array was experimentally demonstrated. Making full use of optical frequency and wavelength information, this system has shown the potentialities of interrogating and demodulating signals from several hundreds FBG sensors on the premise that power of light source is large enough. This system has good prospects in two or three-dimensional distribution stress monitoring of large structures..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 86 (2005)
Second-order Polarization Mode Dispersion and Its Statistical Characteristics in Single Mode Fiber
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The second-order Polarization Mode Dispersion of 22 km and 75 km single mode fiber were measured with Jones matrix eigenanalysis method and Poincare Sphere Method.The parallel component,perpendicular component,depolarization effect,PCD,the statistical charactristics and effects of these components were analyzed thoroulThe second-order Polarization Mode Dispersion of 22 km and 75 km single mode fiber were measured with Jones matrix eigenanalysis method and Poincare Sphere Method.The parallel component,perpendicular component,depolarization effect,PCD,the statistical charactristics and effects of these components were analyzed thorouly.The result is that the perpendicular component had a greater impact on pulse than that of the parallel component in mean. This will be a very helpful researching work for second-order PMD compensation..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 89 (2005)
One Dimensional Photonic Crystal Applied for the Spectrum Modification of BaF2 Scintillation Crystal
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One dimensional photonic crystal was proposed to modify the emission spectrum of BaF 2 scintillation crystal. The photonic crystal was composed of the basic unit, Al 2O 3/MgF 2/Al/ MgF 2. The transmittance spectrum of the photonic crystal and the relevant emission spectrum of the BaF 2 were discussed with relation to pOne dimensional photonic crystal was proposed to modify the emission spectrum of BaF 2 scintillation crystal. The photonic crystal was composed of the basic unit, Al 2O 3/MgF 2/Al/ MgF 2. The transmittance spectrum of the photonic crystal and the relevant emission spectrum of the BaF 2 were discussed with relation to period number, metallic layer thickness and its position in the low refractive index material, emission angle etc. Results show that the attenuation of the fast component is less than 5 times and the relative restraint ratio of the slow component is larger than 20 with the designed photonic crystal. The relative restraint ratio of the slow component can be larger than 100 by selecting appropriate detect angle range..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 94 (2005)
Optical Switch and Bistability Based on Nonlinear One-dimensional Photonic Crystals
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The optical switch and bistability based on nonlinear one-dimensional photonic crystals is designed and manufactured.The device, which has 20 periods, is made from ZnS layers and ZnSe layers alternately. When the incident power density reaches 1.0×10 5 W/cm 2, the Ar ion laser,wavelength of which is 514.5 nm, is sThe optical switch and bistability based on nonlinear one-dimensional photonic crystals is designed and manufactured.The device, which has 20 periods, is made from ZnS layers and ZnSe layers alternately. When the incident power density reaches 1.0×10 5 W/cm 2, the Ar ion laser,wavelength of which is 514.5 nm, is shifted out of the optical bandgap of the one-dimensional nonlinear photonic crystals. Optical switch turns on to a high trasmission state. It also can be made into optical bistability device. The threshold power density of the optical bistability is 1.38×10 5 W/cm 2 and the switching time of the optical bistability is about 100 ps. The experimental results agree well with the theory one..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 98 (2005)
Study of Equivalent Core Radius of Photonic Crystal Fibers
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The effective index of fundamental mode and effective cladding index for index-guiding photonic crystal fibers with triangular lattice are calculated by using finite-difference beam propagation method and plane wave expansion method, respectively. Then the equivalent core radius for photonic crystal fibers is obtained The effective index of fundamental mode and effective cladding index for index-guiding photonic crystal fibers with triangular lattice are calculated by using finite-difference beam propagation method and plane wave expansion method, respectively. Then the equivalent core radius for photonic crystal fibers is obtained through putting them into the mode dispersion equation for step index fibers. Variational regularity of the normalized equivalent radius(r norm=r/Λ) with normalized frequency(Λ/λ) is found out for different photonic crystal fiber parameters. Finally, the approximate formula for r norm as a function of d/Λ and Λ/λ, suitable to 2≤Λ/λ≤10 and 0.2≤d/Λ≤0.7, is given out..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 102 (2005)
Research on a New Adjustment Technique of Playback Wavelength of MBDCG Lippmann Hologram
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A new technique was presented for adjusting the playback wavelength of Lippmann holograms recorded in methylene-blue sensitized dichromated gelatin(MBDCG). The main feature of this technique is introducing a water-soluble organic reagent into MBDCG photosensitive layer as preswelling reagent and wavelength adjuster. ThA new technique was presented for adjusting the playback wavelength of Lippmann holograms recorded in methylene-blue sensitized dichromated gelatin(MBDCG). The main feature of this technique is introducing a water-soluble organic reagent into MBDCG photosensitive layer as preswelling reagent and wavelength adjuster. This method has wide wavelength adjustment range (up to 200 nm) and high signal-to-noise ratio, can be applied to quantitatively adjust the playback wavelength of reflection hologram by changing the concentration of preswelling reagent. Its possible applications include color image display, holographic optical elements, and optical anti-counterfeiting..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 106 (2005)
Imaging Properties of the Computer-generated Holograms Based on a Spatial Light Modulator
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The dynamic computer-generated holographic imaging system with spatial light modulators (SLM) is considered as a special coherent imaging system, and the point spread function (PSF) of this system is derived. Based on the PSF, the apodization and the enlargement caused by the pixelated SLM are analyzed, and the influenThe dynamic computer-generated holographic imaging system with spatial light modulators (SLM) is considered as a special coherent imaging system, and the point spread function (PSF) of this system is derived. Based on the PSF, the apodization and the enlargement caused by the pixelated SLM are analyzed, and the influences of the fill factor of SLM and the diffraction distance on the resolution of this imaging system are investigated by computer simulation. Moreover, the minimum diffraction distance required for sampling theorem is also considered, and a pretreatment method for eliminating this influence is reported. This works is meaningful to the perfection of this system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 110 (2005)
Study on the Kinoform of Frequency-change Sampling
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Based on the imaging theorem and different patial space-frequency characteristic of the kinoform , the kinoform has been sampled by frequency-change,ensuring that the same digitized grade should be taken in the phase difference from 0 to 2π or -π to π. In the way, the information redundancy of the kinoform that resultsBased on the imaging theorem and different patial space-frequency characteristic of the kinoform , the kinoform has been sampled by frequency-change,ensuring that the same digitized grade should be taken in the phase difference from 0 to 2π or -π to π. In the way, the information redundancy of the kinoform that results from the sampling redundancy has been eliminated. Further more, a good reconstructed image can be acquired from restoration kinoform by the nearest interpolation. The feasibility and efficiency of the method are confirmed by theoretical analysis and experimental results. So a new thought has been offered for fast computation, the information storage and transmission of kinoform..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 114 (2005)
A Studing Method of Making Stereo-rainbow Hologram of Outdoor Natural Scenery
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A kind of technology making stereo-rainbow hologram is presented,which can record outdoor natural scenery by continuous laser. Firstly,the primary stereoscopic picture of outdoor natural scenery is taken with the linear lens array camera made by ourselves. Then continuous laser illuminates the primary stereoscopic pictA kind of technology making stereo-rainbow hologram is presented,which can record outdoor natural scenery by continuous laser. Firstly,the primary stereoscopic picture of outdoor natural scenery is taken with the linear lens array camera made by ourselves. Then continuous laser illuminates the primary stereoscopic picture and the stereo-rainbow hologram is fabricated. Here the linear lens array not only has imaging capability, but also acts as the slits of rainbow holography. This technology is the same with outdoor dynamic objects also. In our experiments stereo-rainbow holograms of outdoor natural scenery are fabricated. The results prove that the technique is feasible.The principle of the proposed technique and the experimental result are presented..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 118 (2005)
Analysis on the Photometric Characteristics of Imaging Deflection Measuring System for Bridge
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The calculation of the photometric characteristics such as image plane′s illumination and contrast are presented according to the demand of photoelectric imaging deflection measurement system. The relationship between the source, background radiation, optical system and image sensor is analyzed. Illumination and contraThe calculation of the photometric characteristics such as image plane′s illumination and contrast are presented according to the demand of photoelectric imaging deflection measurement system. The relationship between the source, background radiation, optical system and image sensor is analyzed. Illumination and contrast on the image plane of camera are also discussed when replacing the system′s source with high reflectivital material or using material with low reflectivity replacing background. The result contributes to putting forward the method of photometric design of photoelectric imaging deflection measurement system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 129 (2005)
A fast Identification & Location Algorithm for Moving Targets in TV Theodolite Tracking System
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To meet the demand of TV theodolite tracking system, a new algorithm is proposed in this paper. According to the characteristics of moving targets and tracking system, fast image difference computing method based on angle changes of TV theodolite is found, with calculation much reduced. Then after median filtering and To meet the demand of TV theodolite tracking system, a new algorithm is proposed in this paper. According to the characteristics of moving targets and tracking system, fast image difference computing method based on angle changes of TV theodolite is found, with calculation much reduced. Then after median filtering and image segmentation of difference image,precision location for targets accomplished. Experiment results prove it a fast, stable, effective algorithm and a real-time processing mode in tracking system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 134 (2005)
A Multi-resolution VA-File for High-dimensional Image Feature Matching
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The similarity search of images can be transformed into the point matching in the high-dimensional vector space by the feature extraction and transformation. In order to reduce the curse of dimensionality, a new Vector Approximation File approach based on the multi-resolution data structure is proposed. The new approacThe similarity search of images can be transformed into the point matching in the high-dimensional vector space by the feature extraction and transformation. In order to reduce the curse of dimensionality, a new Vector Approximation File approach based on the multi-resolution data structure is proposed. The new approach computes the lower bound of distance from low-resolution level. If it is larger than the latest maximum distance in the result set, the candidate can be removed without calculating the full-resolution distance. The computational time can be dramatically reduced by eliminating improper candidates at lower levels. The algorithm supporting k-nearest neighbor search is also presented in the new approach and has been applied for feature matching in the large image data sets. The experiment results show that the new approach improves the k-nearest neighbor search speed and outperforms the Vector Approximation File approach..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 138 (2005)
New Image Segmentation Methods Based on Regionally Minimal Cost Watershed Transform
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According to mathematical morphology, a new image segmentation method based on regionally minimal cost watershed transform is introduced. Firstly, local region needing watershed was segmented after erosion、dilation and edge detection by canny. Secondly, the local region of the picture is processed applying the methods According to mathematical morphology, a new image segmentation method based on regionally minimal cost watershed transform is introduced. Firstly, local region needing watershed was segmented after erosion、dilation and edge detection by canny. Secondly, the local region of the picture is processed applying the methods in this paper. And in the last of this paper many rules solving over-segmentation are introduced. Experiments show that the new algorithm′s time is low and the method in this paper has the advantage of giving accurate contour of object..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 142 (2005)
An Image Change Detection Method Using Statistical Analysis
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In order to detect the actrul changes from two remotely sensed multispectral images gained at the same location and at different times, a statistical method is created —Statistical Test. In the method, local regression is applied to the areas of interest from the two images which are gained from two times. And when theIn order to detect the actrul changes from two remotely sensed multispectral images gained at the same location and at different times, a statistical method is created —Statistical Test. In the method, local regression is applied to the areas of interest from the two images which are gained from two times. And when the difference of regression coeffients are very large, these areas of interest are subdivided into more smaller areas. Compared with the conventional methods, the proposed method is not only undependent of the impulse noise, but also the method is not influenced by the apparent changes caused by the sensitivity degradion in sensors or the location changes of the light source..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 146 (2005)
Development of Uncompressed Multichannel Digital Video Optical Fiber Transmission System
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A solution of uncompressed multichannel digital video transmission system is presented.Based on time-division multiplexing technology and the serial digital video transmission,the system can transfer multichannel video signal over a single optical fiber. Designing scheme , main technologies and high speed data interfacA solution of uncompressed multichannel digital video transmission system is presented.Based on time-division multiplexing technology and the serial digital video transmission,the system can transfer multichannel video signal over a single optical fiber. Designing scheme , main technologies and high speed data interface design are introduced in detail.Experiments show that the system works stably and has a good effect of real-time transmission. It is a good and practical scheme for security and surveillance systems..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 150 (2005)
Silicon Nitride Thin Films Deposited by R.F. Magnetron Sputtering
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Silicon nitride thin films were deposited on K9 glass by r.f. magnetron sputtering without heating. Comparisons of the optical properties were made as the films′ deposition conditions changed. Several different deposition routines showed that gas ratio played much more important role than total gas pressure when total Silicon nitride thin films were deposited on K9 glass by r.f. magnetron sputtering without heating. Comparisons of the optical properties were made as the films′ deposition conditions changed. Several different deposition routines showed that gas ratio played much more important role than total gas pressure when total pressure is low. The turning point of Si-rich film and N-rich film lies at the flow rate N 2-to-Ar of 3∶14 . Keeping total pressure low is necessary for the sake of deposition rate and refractive index. SiN x thin films were studied by AFM and UV-VIS scanning spectrophotometer..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 154 (2005)
Non Destructive Testing of Laser Induced Damage in Optical Thin Films by Laser Photothermal Deflection Image
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The principle testing laser induced damage of optical thin films by laser photothemal deflection method (PTDM) and corresponding experimental testing set up are described. The laser induced damage on surface of optical thin films is tested by scanning surface using the set up. Grey image coded by tested two dimensionalThe principle testing laser induced damage of optical thin films by laser photothemal deflection method (PTDM) and corresponding experimental testing set up are described. The laser induced damage on surface of optical thin films is tested by scanning surface using the set up. Grey image coded by tested two dimensional photothermal deflection signals is directly displayed and shown that the testing laser induced damage of optical thin films by PTDM possesses many advantages such as direct display of damage and determination of damage threshold. And the method is available..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 158 (2005)
Optical Device
Study of the Key Technology of Optical Fiber Biosensor
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By using of the Rifs (Reflectometric Interference Spectroscopy) system and the testing result of AFM (atomic force microscope), a novel method for directly monitoring the change of reflectometric spectrum extremum during antigen-antibody interactions is proposed. Experiments show that the process of immunoreactions canBy using of the Rifs (Reflectometric Interference Spectroscopy) system and the testing result of AFM (atomic force microscope), a novel method for directly monitoring the change of reflectometric spectrum extremum during antigen-antibody interactions is proposed. Experiments show that the process of immunoreactions can be directly monitored and the results can be saved continuously by this method. Compared with film thickness extremun method, this method is simple, sensitive and effective for immune dynamics study..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 121 (2005)
The Focus Diffraction Property of Axicons Illuminated by Incident Spherical Wave
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Simple expressions based on the method of stationary-phase are derived for the axis line images produced by acicons illuminated by spherical wave. By using these expressions, the characteristics of its energy flow along axis and the lateral intensity distribution are gotten. The numerical calculations indicate that theSimple expressions based on the method of stationary-phase are derived for the axis line images produced by acicons illuminated by spherical wave. By using these expressions, the characteristics of its energy flow along axis and the lateral intensity distribution are gotten. The numerical calculations indicate that the on –axis intensity distribution and focal depth range can be developed and the lateral intensity distribution may be ensured by choosing correct spherical wave. For the axicons with 20 mm radius, 10 -2 cone angle, when using incident spherical wave whose radius of curvature varius from 1200 mm to 1400 mm, the focal length increases from 200 mm to 120 mm and the lateral intensity distribution increases only 15μm..
Acta Photonica Sinica
- Publication Date: Jan. 01, 2005
- Vol. 34, Issue 1, 126 (2005)
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