Contents
2004
Volume: 24 Issue 2
31 Article(s)
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Research Article
Influence of Crosstalk on the Scalability of Dense Wavelength Division Multiplexing Networks
[in Chinese], and [in Chinese]
Crosstalk is an important limiting factor on the scalability of dense wavelength division multiplexing (DWDM) netwoks. Crosstalk contributions in three types of DWDM cross-connect topologies with dilated Benes switch architecture have been identified. Results show that first-order crosstalk can be removed in the three Crosstalk is an important limiting factor on the scalability of dense wavelength division multiplexing (DWDM) netwoks. Crosstalk contributions in three types of DWDM cross-connect topologies with dilated Benes switch architecture have been identified. Results show that first-order crosstalk can be removed in the three optical cross-connect (OXC) nodes and the second-order crosstalk can be eliminated with narrow-band tunable optical filter introduced in the second scheme. Scalability of intensity-modulation direct-detection DWDM networks which built with the three OXC nodes is compared and discussed by numerical simulation. Results indicate that dilated Benes switch-based OXC nodes have good scalability although they are built with high crosstalk-level component. Although the crosstalk of the optical devices used in OXC node is large, it can be reduced by carefully designing the OXC node topology..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 298 (2004)
Atomic and Molecular Physics
Study of the Characteristics of the Surface Ripple on Si Material Irradiated by Pulsed Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The mechanism of coherent stimulated light scattering and the characteristics of the surface ripple in the laser interaction with materials is described. Experimental research on the surface ripple with Si material irradiated by pulsed laser, is carried out with 1.06 μm laser wave length, 15 mJ energy, 2 mm spot diametThe mechanism of coherent stimulated light scattering and the characteristics of the surface ripple in the laser interaction with materials is described. Experimental research on the surface ripple with Si material irradiated by pulsed laser, is carried out with 1.06 μm laser wave length, 15 mJ energy, 2 mm spot diameter, about 10 ns pulse width and Brewster angle incidence. The surface ripple′s modality of the laser-induced Si material is measured by optical microscope and atomic microscope. A set of liner ripple structure with parallel, equal spaces is found at the surface of silicon material after pulsed laser irradiation under a little higher laser intensity than damage threshold. If this ripple phenomena is related to sound wave velocity in material, the ripple period could be well explained according to the sound wave velocity and pulse duration, and thermal stress is a main role in the formation of surface ripple..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 239 (2004)
Fiber Optics and Optical Communications
Temperature Sensing Properties of Multimode Fiber Grating
[in Chinese], [in Chinese], and [in Chinese]
Fiber Bragg grating was written in hydrogenated multimode fiber, and the temperature sensing properties of multimode fiber gratings are investigated experimentally and theoretically in this paper. Experimental results show that the Bragg wavelength of grating in multimode graded-index fiber is linearly dependent on itsFiber Bragg grating was written in hydrogenated multimode fiber, and the temperature sensing properties of multimode fiber gratings are investigated experimentally and theoretically in this paper. Experimental results show that the Bragg wavelength of grating in multimode graded-index fiber is linearly dependent on its temperature; and its repeatability is good. The measured temperature sensitivity of each reflection peak is equal to 0.0098 nm/℃; the temperature sensitivity attained from experimental data is tallies with theoretical analysis. The characteristics are similar to that of a conventional Bragg grating in single-mode fiber. So the multimode fiber grating may replace single-mode fiber grating to produce fiber sensors. The experimental results can also provide guidance for further studying on multimode fiber Bragg gratings..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 175 (2004)
Synthesis and Fabrication of Fiber Bragg Gratings with Triangular and Broad-Bandwidth Reflection Spectrum
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The fiber Bragg gratings with triangular spectrum will have important applications in fiber sensing areas. The coupling coefficient distribution along the length is acquired for triangular spectrum fiber Bragg gratings by using genetic algorithms synthesizing. The simulation results show that the triangular fiber BraggThe fiber Bragg gratings with triangular spectrum will have important applications in fiber sensing areas. The coupling coefficient distribution along the length is acquired for triangular spectrum fiber Bragg gratings by using genetic algorithms synthesizing. The simulation results show that the triangular fiber Bragg gratings can be realized; the reflection bandwidth can be adjusted by chirping of the grating; uniform fiber Bragg gratings have small reflection bandwidth, while the gratings with chirped period have larger reflection bandwidth, which is similar to the chirp. A triangular fiber Bragg grating with 0.77 nm base width of reflection spectrum is fabricated experimentally by using a scanning method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 179 (2004)
A Novel Extrinsic FiberOptic FabryPerot Interferometric Sensing System Based on Optical Amplification
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel method of enhancing the signal level of extrinsic fiber-optic Fabry-Perot interferometer (EFPI) is proposed and demonstrated. This method is based on the simultaneous use of the amplified spontaneous emission (ASE) and optical amplification of an erbium-doped fiber (EDF) pumped by a 980 nm laser diode. The imprA novel method of enhancing the signal level of extrinsic fiber-optic Fabry-Perot interferometer (EFPI) is proposed and demonstrated. This method is based on the simultaneous use of the amplified spontaneous emission (ASE) and optical amplification of an erbium-doped fiber (EDF) pumped by a 980 nm laser diode. The improvement in interferometric signal level is very significant as an enhancement of 4 orders of magnitude can be achieved. An experiment is carried out to verify this concept. An improvement of 43 dB in signal level has been achieved with a small pump power of ～30 mW. The strain accuracy has been improved by a factor of two compared with authors' previous EFPI system without optical amplification. Such an EFPI system has a good performance-to-price ratio since it can enhance the optical intensity greatly while it doesn't increase the cost of the sensor system significantly..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 183 (2004)
A High-Sensitivity inFiber Bragg Grating Pressure Sensor
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Based on in-fiber Bragg grating sensing model, a high-sensitivity in-fiber Bragg grating pressure sensor was proposed by using uniform strength beam and bellow. The analytical formulae between pressure and relative shift of Bragg wavelength of in-fiber Bragg grating were derived. The pressure sensitivity coefficients wBased on in-fiber Bragg grating sensing model, a high-sensitivity in-fiber Bragg grating pressure sensor was proposed by using uniform strength beam and bellow. The analytical formulae between pressure and relative shift of Bragg wavelength of in-fiber Bragg grating were derived. The pressure sensitivity coefficients were also obtained by analytical formulae and experiment respectively. The theoretical and experimental pressure sensitivity coefficients could reach 1.476×10-2 MPa-1 and 1.35×10-2 MPa-1, which were 7455 and 6808 times of that of the bare-fiber grating respectively. The experimental result fits the theoretical one well. At the same time, it was pointed out that the pressure sensitivity coefficients of this kind of sensor could be very large by regulating the parameters of strength beam and bellow till the in-fiber Bragg gratings were damaged..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 187 (2004)
Ring Cavity Yb3+-Doped Fiber Laser with Frequency Selecting by Fiber Bragg Grating
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 190 (2004)
The Characteristics Analysis of an Integrated Optical Acoustooptic Tunable Filter Based on Spectrometer
[in Chinese], [in Chinese], and [in Chinese]
An integrated optical acoustooptic tunable filter (AOTF)-based new type spectrometer is brought forward, and its characteristics are introduced in detail. Through analysis of the transmission functions, point spread function and dispersion power of the spectrometer detailedly, it is pointed out that the spectral resoluAn integrated optical acoustooptic tunable filter (AOTF)-based new type spectrometer is brought forward, and its characteristics are introduced in detail. Through analysis of the transmission functions, point spread function and dispersion power of the spectrometer detailedly, it is pointed out that the spectral resolution is proportional to acoustooptic interaction length L, and the square root of the number of stages. So the resolution can be enhanced more effectively by increasing acoustooptic interaction length L than increasing the number of stages. In addition, it is proposed that quasi-collinear acoustooptic coupling is a effective way to suppress sidelopes and improve the resolution of AOTF spectrometer. The testing the quasi-collinear device shows that as the acoustooptical coupling length is 25 mm and the angle between acoustical and optical waveguid is 0.42°, it is obtained that the measured FWHM is 1.44 nm when the acoustic frequency is about 174 MHz,the measured sidelobes level is -13.2 dB and the mode-conversion efficiency of 99%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 195 (2004)
A Novel Method of Edge Filter Linear Demodulation Using Long-Period Grating in Fiber Sensor System
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel demodulation method of fiber Bragg grating sensor is presented. Based on the filter characteristics of long-period grating, it is used as the filter component of the demodulation system. An experimental system is built up to achieve one or multi channels of sensor demodulation. Using this method based on intensA novel demodulation method of fiber Bragg grating sensor is presented. Based on the filter characteristics of long-period grating, it is used as the filter component of the demodulation system. An experimental system is built up to achieve one or multi channels of sensor demodulation. Using this method based on intensity, it can achieve linear demodulation with a bandwidth of 5 nm. And the resolving wavelength is 0.002 nm, with the demodulation speed up to 10 kHz. The experimental results were analyzed in detail. The advantages of this system are an all-fiber design, quasistatic and dynamic operation, and potential high-speed demodulation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 199 (2004)
Transition Loss and Polarization Effect in Planar Lightwave Circuits Based on Silicon-on-Insulator Rib Waveguides
[in Chinese], [in Chinese], and [in Chinese]
Four kinds of star couplers with different structures at rib-to-slab and slab-to-rib transition region on silicon-on-insulator are fabricated. The testing results are consistent with the theoretical calculation in which transition loss about 1 dB by using taper waveguides was obtained. The loss is caused by mode dismatFour kinds of star couplers with different structures at rib-to-slab and slab-to-rib transition region on silicon-on-insulator are fabricated. The testing results are consistent with the theoretical calculation in which transition loss about 1 dB by using taper waveguides was obtained. The loss is caused by mode dismatching between the rib waveguides and slab waveguides. Polarization effect in SOI rib waveguides is also discussed. Experimental data in the released literature are quoted to validate the analysis method. And the effective index difference which is as low as 10-5 order between two polarizations of single mode rib waveguides is obtained by optimal design for the rib waveguide thickness, rib height, rib width. In fact this so little effect can be neglected in practical design..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 203 (2004)
A Study of the Influence of Polarization Mode Dispersion in Dispersion-Managed Soliton Transmission Systems
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The rule of dispersion-managed soliton transmission in birefringent fiber is analyzed by variational method. Firstly,The model of perturbed soliton transmission in birefringent fiber is built, and then the rule of transmission evolvement of the DMS parameters influenced by PMD is analyzed, at the last, the analysis resThe rule of dispersion-managed soliton transmission in birefringent fiber is analyzed by variational method. Firstly,The model of perturbed soliton transmission in birefringent fiber is built, and then the rule of transmission evolvement of the DMS parameters influenced by PMD is analyzed, at the last, the analysis results are numerical computed. The results indicate that the parameter of PMD has a great impact on the energy and width of DMS evolution. While the PMD is big like as the Dp>0.3 ps/km1/2, the some of online control methods must be used to restrain the PMD effects on this transmission system, but if Dp≤0.1 ps/km1/2, the transmission system can hardly be effected by PMD. The results also prove that the DMS possess a characteristic of robustness to PMD. These results provide the theoretical evidence and research way for studying influence of PMD in systems of high-speed nonlinear pulse transmission, particularly in DMS system transmission..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 215 (2004)
The Dispersion Compensation of Optical Fiber Bragg Grating on the Long-Distance G.652 Fiber Transmission System
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The coupled mode theory of fiber Bragg grating (FBG) is analyzed. The fabrication course of FBG is explored and optimized, and the good quality FBGs with the wavelengths that fit the ITU-T criterion are made. The 4×10 Gb/s-400 km and 4×10 Gb/s-800 km transmission systems on G.652 fiber with dispersion compensThe coupled mode theory of fiber Bragg grating (FBG) is analyzed. The fabrication course of FBG is explored and optimized, and the good quality FBGs with the wavelengths that fit the ITU-T criterion are made. The 4×10 Gb/s-400 km and 4×10 Gb/s-800 km transmission systems on G.652 fiber with dispersion compensation by FBGs are implemented. The FBGs are made by double lens and scanning stage with phase mask, respectively. The power penalty is less than 2 dB in each channel, and the best power penalty is negative. And the polarization mode dispersion (PMD) of 4×10 Gb/s-800 km transmission system is monitored for a long time. The result shows that in 10 Gb/s system, the PMD compensation is not needed. Developing the 10 Gb/s transmission system fits the situation of China..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 220 (2004)
Research of Algebraic Congruent Codes Used in TwoDimensional Code Division Multiaddress System
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
After summarizing the application of linear, quadratic and hyperbolic operators in CDMA system, a generalized algebraic congruent code is given out by its construction formula in three different categories, which are frequency-hop (FH), time-spread (TS) and FH-TS codes. A novel two-dimensional optical CDMA system is giAfter summarizing the application of linear, quadratic and hyperbolic operators in CDMA system, a generalized algebraic congruent code is given out by its construction formula in three different categories, which are frequency-hop (FH), time-spread (TS) and FH-TS codes. A novel two-dimensional optical CDMA system is given out, in which different categories of codes are used to provide different types of service. Such a OCDMA system is very fit for the case that a small part of services are with high bit rate or high quality of service, while great amount of services are common one. In order to prove the possibility of such a hybrid system, the cross-correlation constants between those three codes are given firstly, the probabilities to attend those cross-correlation values are calculated secondly, system's BER performances under several different types of interferences are provided at last. Numerical analysis and discussion is also given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 225 (2004)
Fourier Optics and Signal Processing
Double Refraction and Reflection of Sequential Interfaces in a Crystal and Application to Integration of 1×N Optical Witch
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The general formulation of double refraction or internal double reflection with different directions of propagation vector and wave vector in a uniaxial crystal is analyzed in terms of the Huygens principle. Then double refraction and double reflection along the sequential interfaces in a crystal are discussed. With thThe general formulation of double refraction or internal double reflection with different directions of propagation vector and wave vector in a uniaxial crystal is analyzed in terms of the Huygens principle. Then double refraction and double reflection along the sequential interfaces in a crystal are discussed. With the relations between the output of the former interface and the input of the latter, double refraction and/or double internal reflection in a crystal along two and multiple successive interfaces can be calculated. On this basis, a configuration of electrooptic 1×N optical switch integrated in a single slab of LiNbO3 is suggested, which consists of an array of electrooptic polarization modulators between the interfaces for total internal reflection. Due to double refraction effect, the ordinary ray and the extraordinary ray have different reflections. From different switching states of modulators, internal double reflection along the sequential interfaces of a crystal can lead to different directions of the output beam. The suggested 1×N optical switch is simple and compact in construction, low in loss and insensitive to environment. An experimental 1×4 switch is demonstrated, too..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 152 (2004)
Improvement of The Reconstruction Algorithm of Optical Computerized Tomography
[in Chinese], and [in Chinese]
Optical computerized tomography (OCT) has found wide applications in the noncontact detection of the flow field such as temperature filed, density field etc. However, the reconstruction of OCT is a projection reconstruction of incomplete data, and the algebra reconstruction technique usually adopted cannot solve the prOptical computerized tomography (OCT) has found wide applications in the noncontact detection of the flow field such as temperature filed, density field etc. However, the reconstruction of OCT is a projection reconstruction of incomplete data, and the algebra reconstruction technique usually adopted cannot solve the problem of reconstruction precision very well. A new kind of algebra reconstruction technique is presented. The property matrix including the prior knowledge is introduced. The fixed ultra-relaxation coefficient usually determined artificially is abandoned and an unfixed ultra-relaxation coefficient is adopted in the algorithm. The reconstruction results indicate that the algorithm with property matrix and unfixed ultra-relaxation coefficient can reconstruct the flow field of incomplete data satisfactorily, improve the reconstruction precision greatly, and match the measured results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 158 (2004)
Five-Step Color Phase-Shifting Technique in Digital Photoelasticity and Its Applications
[in Chinese], [in Chinese], and [in Chinese]
Combined color imaging with phase shifting, a technique named five-step color phase shifting (CPST) is presented to determine principal direction angle and the whole-field single isoclinic phase map in the range of [0,π/2]. A digital camera recorded five isoclinic color images coupled with isochromatics from a plane poCombined color imaging with phase shifting, a technique named five-step color phase shifting (CPST) is presented to determine principal direction angle and the whole-field single isoclinic phase map in the range of [0,π/2]. A digital camera recorded five isoclinic color images coupled with isochromatics from a plane polariscope with five different settings, respectively. The unloaded light intensity image is introduced to operation. For knowing the accuracy of the CPST influenced by the different error sources, such as measuring intensities errors, orientation errors, and especially the initial stress errors, methods are given to analyze and estimate the influence of the different error sources on the final calculated isoclinic results. Experiments have been carried out with the simulation of a circular disk under diametral compression and some actual applications. This technique utilizes white light, which avoids undefined isoclinics near the locations where the isochromatics exist, and will have active effect on experimental stress analysis and structural strength design..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 162 (2004)
Geometric Optics
Green Function Method for the Numerical Calculations of Pinhole Diffraction and Near-Field Light Scattering
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Starting from the Helmholtz Equation, the integral equation of light wave on medium interfaces is obtained by use of Green theorem. Then the integral equation is discretized into a set of linear equations with unknown values of light wave and its derivative on the interface. Numerical solutions of these linear equationStarting from the Helmholtz Equation, the integral equation of light wave on medium interfaces is obtained by use of Green theorem. Then the integral equation is discretized into a set of linear equations with unknown values of light wave and its derivative on the interface. Numerical solutions of these linear equations give the values of light waves. This method is applied to the calculations of both the pinhole diffraction in subwavelength scale and random light field produced by random self-affine fractal surfaces in near field. A method for generation of random self-affine fractal surfaces is proposed by analogy to the derivation process of the autocorrelation functions of speckles in Frauhofer plane, and the Fourier transformation method for numerical derivative of the random surfaces is presented. The calculated results show that in near field, the random light fields vary dramatically with the distance increasing from the random surfaces, and the properties of light wave propagation are quite different from those of the light waves in far field..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 145 (2004)
Lasers and Laser Optics
Generalized M2 Factor of Laser Beams with Amplitude Modulations and Phase Distortion Passing Through Hard-Edge Apertures
[in Chinese], [in Chinese], and [in Chinese]
The beam propagation M2 factor is a useful parameter for characterizing laser beam. By using the treatment that the rectangular function can be expanded into an approximate sum of complex Gaussian functions with finite numbers, approximate formulas for the second-order moments of partially coherent beam after it passesThe beam propagation M2 factor is a useful parameter for characterizing laser beam. By using the treatment that the rectangular function can be expanded into an approximate sum of complex Gaussian functions with finite numbers, approximate formulas for the second-order moments of partially coherent beam after it passes hard-edge diaphragm are given. The generalized M2 factor of partially coherent beam after it passes hard-edge diaphragm can be obtained. A laser beam with amplitude modulation and phase distortion is taken as a typical example of partially coherent beams. The analytical expression for the generalized M2 factor is derived. The calculation precision of our method is analyzed by numerical calculations. It can been seen from the study that by making use of the approximate calculation method proposed, the calculation error for the generalized M2 factor is less than 1% and the approximate analytic expressions can be obtained immediately. Consequently, the calculation can be simplified and the calculation efficiency can be improved efficiently..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 274 (2004)
Analysis of Monolithic Nonplanar Ring Oscillators by Considering the Stress-Induced Birefringence
[in Chinese], [in Chinese], and [in Chinese]
The principle of monolithic nonplanar ring single-frequency laser was introduced, and eigenpolarization states of monolithic unidirectional traveling wave nonplanar ring oscillator (NPRO) were calculated by Jones matrix. The influences of magnetic field strength, reflection coefficients of the output coupler, incident The principle of monolithic nonplanar ring single-frequency laser was introduced, and eigenpolarization states of monolithic unidirectional traveling wave nonplanar ring oscillator (NPRO) were calculated by Jones matrix. The influences of magnetic field strength, reflection coefficients of the output coupler, incident angle, nonplanar angle and other parameters inside cavity on the loss and loss difference of eigenpolarizations were analyzed. How to choose the parameters of cavity to decrease the loss of eigenpolarization states and increase the loss difference between two eigenpolarization states was pointed out. The influences of the stress direction and the stress-induced birefringence coefficient on the loss and loss difference of the eigenpolarization states in the cavity were discussed by calculating the phase difference between two eigenpolarization states induced by stress birefringence..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 279 (2004)
The Function of a Brewster Angle-Positioned Birefrigent Filter in Improvement of Intracavity Frequency Doubling
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The functions of birefringent filter(BF) narrowing the operation line width of fundamental-wave laser, and improving the stability of frequency-doubling laser are investigated in experiment and theory. The dependence of line width of fundamental wave and frequency-doubling efficiency on the thickness of BF, the thermalThe functions of birefringent filter(BF) narrowing the operation line width of fundamental-wave laser, and improving the stability of frequency-doubling laser are investigated in experiment and theory. The dependence of line width of fundamental wave and frequency-doubling efficiency on the thickness of BF, the thermal source in oscillator, the compensation for thermal effect with BF, and the position of BF in cavity, are investigated experimentally. The experimental results presents that BF not only can narrow the line width of fundamental wave, but also compensate for the birefringence induced by thermal effect of intracavity elements, and decrease the laser loss, further increase dramatically the efficiency of frequency doubling and stability..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 284 (2004)
Nonlinear Optics
Optical Limiting Characteristics Dependent on Pump Energy in Stimulated Brillouin Scattering Process
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Adopting a noise-initiation mode of stimulated brillouin scattering (SBS), optical limiting effect are numerically simulated by using 7 ns, 1064 nm, Nd∶YAG laser pulses within CCl4 liquid in SBS process. When the pump energies are low, the nonlinear medium can be optical transparent. When pump energies are higher than Adopting a noise-initiation mode of stimulated brillouin scattering (SBS), optical limiting effect are numerically simulated by using 7 ns, 1064 nm, Nd∶YAG laser pulses within CCl4 liquid in SBS process. When the pump energies are low, the nonlinear medium can be optical transparent. When pump energies are higher than the threshold of stimulated Brillouin scattering, the peak powers of nanosecond laser pulses are limited, pulses are narrowed and the energies tend to saturated. This means the optical limiting has both power limiting and energy limiting characteristics. The relationships of optical limiting effect such as output peak power, output energy, transmissivity and pulse compression ratio versus pump energy are investigated by a theoretical model. The experimental results of above optical limiting effects were given. In authors' experimental regime, results were in good agreement with the conclusions predicted by theoretical simulations..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 168 (2004)
LiNbO3 Electrooptic Tuning Optical Parametric Oscillator
[in Chinese], [in Chinese], and [in Chinese]
The main problems of classical angle-tuning and temperature-control tuning in optical parametric oscillator are the complexity of operation and slowness of tuning rate. However, electrooptic tuning takes advantage over in operation and rates. Based on the electrooptical effect of the nonlinear optic crystal LiNbO3, pumThe main problems of classical angle-tuning and temperature-control tuning in optical parametric oscillator are the complexity of operation and slowness of tuning rate. However, electrooptic tuning takes advantage over in operation and rates. Based on the electrooptical effect of the nonlinear optic crystal LiNbO3, pumped by 1.064 μm Nd∶YAG laser, when the cut angle θ=47.5°, DC voltage varying in the range of -4.5～4.5 kV is applied to LiNbO3 and tunable output of optical parametric oscillator is obtained. The maximum output energy is ～2.6 mJ and the conversion efficiency η is ～17.3%. The experimental results agree well with the theoretical calculation. This is a viable novel approach for changing the optical parametric wavelength..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 172 (2004)
Physical Optics
Bidirectional Reflectance Distribution Function of Aluminium Diffuser at UV Spectral Band
[in Chinese], and [in Chinese]
The experimental setup for the measurement of aluminium diffuser′s bidirectional reflectance distribution function has been established by choosing a proper illuminating and viewing method. Characteristics of aluminium diffuser′s bidirectional reflectance distribution function under different situation are studied in eThe experimental setup for the measurement of aluminium diffuser′s bidirectional reflectance distribution function has been established by choosing a proper illuminating and viewing method. Characteristics of aluminium diffuser′s bidirectional reflectance distribution function under different situation are studied in experiment. The change trends of bidirectional reflectance distribution function with wavelength of different surfaces roughness of Al diffusers are different; after coated with Al+MgF2,the reflectance increase approximately from 1.5 to 3 times; from 200 to 280 nm, the relative bidirectional reflectance distribution function of Al diffuser does not change with wavelength, but it increases up to 13 percent while wavelength is longer than 280 nm. Contour plots resulting from experimental data show the change of aluminium diffuser′s bidirectional reflectance distribution function with different illuminating angles while viewing angles are fixed, a fitted empiristic formula in such case is given, its relative accuracy is 2.4 percent..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 230 (2004)
Phase-Compensation Design of Isosceles Blazed Grating
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A new type of isosceles blazed grating with compensated phase on the obverse side (IBGCPOS) is designed. Isosceles design ensures the positive and negative diffractive orders distributing on the two sides of the grating normal symmetrically. By optimizing the size of the groove to observe phase compensation, the diffraA new type of isosceles blazed grating with compensated phase on the obverse side (IBGCPOS) is designed. Isosceles design ensures the positive and negative diffractive orders distributing on the two sides of the grating normal symmetrically. By optimizing the size of the groove to observe phase compensation, the diffractive energy can be transferred to the middle orders. Two maximum diffractive directions are reserved. Energy distribution of zeroth order and higher orders diffraction is restrained, which can avoid energy wasting. Moreover,the problems of double-sided fabricating alignment and multiple-diffraction are solved. The theoretical model of diffraction intensity is founded and simulated by computer. The difference between IBGCPOS and the isosceles blazed grating with compensated phase on the inverse side (IBGCPIS) is analyzed. Typical distribution figures of diffraction intensity are given. In addition, the fabricating method with gray-scale mask for the new type grating is discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 235 (2004)
Measurement System of Projection Lens Based on CCD Modulation Transfer Function
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Modulation transfer function is a common method for evaluating the performance of optical imaging system. The measurement of MTF is very important in production and testing. But there is no standard quantitative method for the measurement of projection lens in the production of projection display system. A new method oModulation transfer function is a common method for evaluating the performance of optical imaging system. The measurement of MTF is very important in production and testing. But there is no standard quantitative method for the measurement of projection lens in the production of projection display system. A new method of measuring LCD projection lens' MTF with CCD imaging system placed on the image plane is introduced. The method is based on the theory of Fourier transform and linear system, and can provide a quantified standard for lens measurement. At the end, the testing results of some practical objective lenses are presented and compared with the designed MTF. Factors that will affect system accuracy are also analyzed here..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 260 (2004)
Sensitization of Ga3+ Ion on the Characteristic Fluorescence of Tb3+∶YAG Layers Grown by LPE
[in Chinese], [in Chinese], and [in Chinese]
Tb3+∶YAGG monocrystalline layers are grown by liquid phase epitaxy (LPE) method. The study of sensitization of Ga3+ on the fluorescent properties of those epitaxially grown Tb3+∶YAGG layers are presented. The doping of Ga3+ in YAG with the replacement of a portion of Al3+ can give quite improvement on the brightness anTb3+∶YAGG monocrystalline layers are grown by liquid phase epitaxy (LPE) method. The study of sensitization of Ga3+ on the fluorescent properties of those epitaxially grown Tb3+∶YAGG layers are presented. The doping of Ga3+ in YAG with the replacement of a portion of Al3+ can give quite improvement on the brightness and the saturation characteristics of Tb3+.
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 264 (2004)
Accurate Measurement of Print Grain Index of Color Film
[in Chinese], [in Chinese], and [in Chinese]
The properties of the color film and the affecting factors when measuring the print grain index value have been analyzed. The film measuring point of print grain index should be made according to its light-sensitive characteristics, being the density corresponding to the 0.74 gray density of color paper when printing; The properties of the color film and the affecting factors when measuring the print grain index value have been analyzed. The film measuring point of print grain index should be made according to its light-sensitive characteristics, being the density corresponding to the 0.74 gray density of color paper when printing; the two main factors affecting print grain index accuracy are contrast amendment factor a of the color paper and cover power efficiency ECP of the color film. The methods of obtaining a and ECP are found, and these two efficiencies of several films have been measured. Finally, the print grain index amendment arousing from the variation of a(ECP) is calculated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 268 (2004)
Spectroscopy
Study of the (4,0) and (5,0) Spectral Bands in the Triplet System d3Δ-a{sup>3Π of CO
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Optical heterodyne magnetic rotation enhanced concentration modulation spectroscopy which is a high sensitive spectroscopic technique for detection of transient and excited molecules, is employed to directly observe the rovibronic absorption spectrum of CO (d3Δ←a3Π) in the regions of 16400～16500 cm-1 and 17450～17750 cmOptical heterodyne magnetic rotation enhanced concentration modulation spectroscopy which is a high sensitive spectroscopic technique for detection of transient and excited molecules, is employed to directly observe the rovibronic absorption spectrum of CO (d3Δ←a3Π) in the regions of 16400～16500 cm-1 and 17450～17750 cm-1 respectively. The (4,0) and (5,0) bands of CO triplet system were observed and analyzed by taking account of the perturbation interaction between the d3Δ1 (v=4),d3Δ2 (v=4) states and A1Π(v=0),D1Δ (v=0) states, respectively, d3Δ1 (v=5) and A1Π (v=1) states as well. A set of precise rotational molecular constants for the d3Δ (v=4,5) have been determined..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 255 (2004)
Thin Films
Reflection Properties of Dielectric Mirror with Weak Absorption Using Equivalent-Cavity Model
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
By using equivalent-cavity model, quarter-wave multilayer dielectric mirrors are studied. For the reflection coefficient with the form as ρ(ω)exp[iψ(ω)], it is proved that around the central frequency ω0 of the mirror, ρ(ω) is equal to ρ(ω0) and ψ(ω) is proportional to the frequency ω. And the expressions for the refleBy using equivalent-cavity model, quarter-wave multilayer dielectric mirrors are studied. For the reflection coefficient with the form as ρ(ω)exp[iψ(ω)], it is proved that around the central frequency ω0 of the mirror, ρ(ω) is equal to ρ(ω0) and ψ(ω) is proportional to the frequency ω. And the expressions for the reflectivity reductions and reflection delays of the weakly absorptive quarter-wave multilayer dielectric mirrors are derived. Studies are made on the dependence of the reflectivity reductions and reflection delays on the parity of the layer number. Based upon these studies, A set of weighting factors is extracted, which can be used to quantify the contributions of any individual layer to such important mirror characteristics as reflection reduction, reflection delay, etc..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 243 (2004)
Polarization Properties of Anodic Alumina Film with Implanted Nanohole Metallic Arrays
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Anodic alumina formed by electrochemical oxidation has a fine structure with a nanohole array. Cu is implanted into the pores of anodic alumina by means of electroplating. With such metallic array, the alumina film exhibits polarization properties like a wire grid polarizer. At the wavelength of 1.5 μm, the film embeddAnodic alumina formed by electrochemical oxidation has a fine structure with a nanohole array. Cu is implanted into the pores of anodic alumina by means of electroplating. With such metallic array, the alumina film exhibits polarization properties like a wire grid polarizer. At the wavelength of 1.5 μm, the film embedded manifests higher transmissivity and better extinction ratio. The dependence of the polarization properties on anodization and electroplating conditions is also studied. To a certain extent, the extinction is enhancing with the increase of anodic oxidation voltage. With the electroplating current density growing, the polarization property is also increasing because of the growth of metallic columns, but the trend is stopped when the current density is too high to make the Joule heat exhale as quickly as possible and result in the irregularity of the columns. The simple microprocessing techniques, the low cost and the small bulk make the film embedded Cu extensive prospects in optical telecommunication..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 247 (2004)
Effect of Spectral Width of Thickness-Monitoring System on Performance of Narrow-Band Filters
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The effect of spectral width of thickness-monitoring system on performance of wavelength division multiplexing (WDM) filters is discussed. Unusual thickness-monitoring signal during deposition is analyzed, which is because of wide spectral width and deviation between monitoring wavelength and central wavelength of the The effect of spectral width of thickness-monitoring system on performance of wavelength division multiplexing (WDM) filters is discussed. Unusual thickness-monitoring signal during deposition is analyzed, which is because of wide spectral width and deviation between monitoring wavelength and central wavelength of the filter. Therefore the spectral width of thickness-monitoring system must be less than half of the turning wavelength width for last two layers of single Fabry-Perot filter. This means that spectral width should be at least less than 0.2 nm for a 100 GHz filter. When the central wavelength is deviated, the thickness error occurs. The signal change regularity for high index and low index materials is shown. When central wavelength is longer than monitoring wavelength, the thickness becomes thinner; and when central wavelength is shorter than monitoring wavelength, the monitoring signal will change in unusual way. These induce a large thickness error, and make maximum transmittance drop and full width at half maximum (FWHM) increase..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 2, 251 (2004)
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