Contents
2007
Volume: 27 Issue 8
37 Article(s)
Export citation format
Research Article
Determination of Lidar Geometric form Factor with Pure Rotational Raman Scattering Signal
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A new method was presented to determine lidar geometric form factor. The intensity distribution charateristic of pure rotational Raman spectra at different temperature is studied. Lidar geometric form factor can be determined accurately with the sum of pure rotational Raman lidar signal and the Rayleigh-Mie lidar signaA new method was presented to determine lidar geometric form factor. The intensity distribution charateristic of pure rotational Raman spectra at different temperature is studied. Lidar geometric form factor can be determined accurately with the sum of pure rotational Raman lidar signal and the Rayleigh-Mie lidar signal of atmospheric molecules. The method reduces aerosol wavelength exponent effect compared with vibrational Raman method and aerosol uniformity limit in contrast to horizontal determination method. The numerical simulation shows that the maximum relative error of geometric form factor retrieved from three kinds of temperature distribution modes and three kinds of aerosol wavelength exponent distribution modes is less than 0.5%. The lidar deomenic form factor is determined with real lidar aignal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1349 (2007)
Simulation and Analysis of Stochastic Parallel Gradient Descent Control Algorithm for Adaptive Optics System
[in Chinese], [in Chinese], and [in Chinese]
The stochastic parallel gradient descent (SPGD) algorithm can optimize the system performance directly, while being independent of wave-front sensor. Based on SPGD algorithm, an adaptive optics system model with a 32-element deformable mirror was simulated. Convergence of SPGD algorithm was verified through analyzing cThe stochastic parallel gradient descent (SPGD) algorithm can optimize the system performance directly, while being independent of wave-front sensor. Based on SPGD algorithm, an adaptive optics system model with a 32-element deformable mirror was simulated. Convergence of SPGD algorithm was verified through analyzing correction capabilities for static wave-front aberrations. The relationship of algorithm gain coefficient, stochastic perturbation amplitude and convergence rate were discussed. Convergence rate can be improved by adaptive adjustment of algorithm gain coefficient..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1355 (2007)
Atmospheric Turbulence Outer Scale Measurement Based on Angle-of-Arrival Covariance
[in Chinese], [in Chinese], and [in Chinese]
According to atmospheric turbulence phase structure function, the relation between the angle-of-arrival covariance of two points and the atmospheric turbulence outer scale is deduced, and normalized by the differential angle-of-arrival variance. The expression of outer scale by the ratio of angle-of-arrival variance anAccording to atmospheric turbulence phase structure function, the relation between the angle-of-arrival covariance of two points and the atmospheric turbulence outer scale is deduced, and normalized by the differential angle-of-arrival variance. The expression of outer scale by the ratio of angle-of-arrival variance and angle-of-arrival covariance is obtained. The experimental results for horizontal propagation in the real atmosphere by four-aperture angle-of-arrival variance measuring apparatus show that the average outer scale is about 4 m at the height of 6 m above the ground. Further more the outer scale changes with time, and they are different in different directions..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1361 (2007)
Scheme of Stepped Slowing Rb Atomic Beams by Isotropic Laser Light
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
We calculated the radiation force on atoms in an isotropic light produced by an integrating sphere. Then we present a new scheme of atomic beam slowing by 5 integrating spheres which are arranged in series with detuning of laser and atomic transition frequency from -70Γ to -10Γ respectively. The numerical results show We calculated the radiation force on atoms in an isotropic light produced by an integrating sphere. Then we present a new scheme of atomic beam slowing by 5 integrating spheres which are arranged in series with detuning of laser and atomic transition frequency from -70Γ to -10Γ respectively. The numerical results show that we can capture the atoms with velocity less than 331 m/s, and slow them down to less than 1 m/s, close to the Doppler limit..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1366 (2007)
Bi-Grating Imaging Analysis by Fresnel Diffraction Theory
[in Chinese], and [in Chinese]
The phenomenon of bi-grating imaging is theoretically studied with Fresnel diffraction theory and Fresnel diffraction formula of plane transmission grating, respectively. The distribution of complex amplitudes of the object waves after passing a system composed of two parallel plane transmission gratings is analyzed. AThe phenomenon of bi-grating imaging is theoretically studied with Fresnel diffraction theory and Fresnel diffraction formula of plane transmission grating, respectively. The distribution of complex amplitudes of the object waves after passing a system composed of two parallel plane transmission gratings is analyzed. A virtual image of the object is observed clearly behind the second grating under ideal conditions when the positions of two gratings meet special value. The function of the two gratings is analyzed theoretically during the process of bi-grating imaging and the relation formula among the two gratings' spatial frequencies, diffraction wave orders and positions necessary for obtaining bi-grating diffraction imaging is given. The result is satisfied with those of experiments..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1371 (2007)
Diffraction of Collimated Beam through Two-Dimensional Mechanical Collimator
[in Chinese], [in Chinese], and [in Chinese]
Assuming that the incident light is from different directions, the process of the incident light passing a series of grids with different intervals has been described and analyzed by applying two-dimensional Fourier optical method. A formula for the distribution of the collimated beam's spatial frequency is establiAssuming that the incident light is from different directions, the process of the incident light passing a series of grids with different intervals has been described and analyzed by applying two-dimensional Fourier optical method. A formula for the distribution of the collimated beam's spatial frequency is established and the spatial frequency distribution of the incident light is obtained. The main procedures and key points in the calculation are listed. When the incident light is from every direction, the calculation demonstrates the collimation performance, when the incident radiation strikes on the collimator paralle, the calculated result shows the diffraction of the collimated beam. The diffraction reaches out of the geometrical shade. The two-dimensional distribution of the collimated beam's spatial frequencies is obtained. The data agree better with the published experimental result than the one-dimensional calculation of foreign peers. This method is a quick and accurate way to calculate the performance of the collimator..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1377 (2007)
40 Gb/s Clock Recovery Based on Optical Phase-Locked Loop
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel optical phase-locked loop (OPLL) based on four-wave-mixing in optical fibers and optical voltage-controlled oscillator (OVCO) is proposed and built to perform clock recovery in optical time-division multiplexed systems. The operation principle of the optical phase-locked loop and the configurations and functionA novel optical phase-locked loop (OPLL) based on four-wave-mixing in optical fibers and optical voltage-controlled oscillator (OVCO) is proposed and built to perform clock recovery in optical time-division multiplexed systems. The operation principle of the optical phase-locked loop and the configurations and functions of modules in optical phase-locked loop are analyzed theoretically. With the use of highly-nonlinear fibers in all-optical phase detector, the fiber length is shortened sufficiently, which reduces the walk-off between two pulse trains induced by dispersion. The phase detector has an extinction ratio beyond 30 dB. The optical voltage-controlled oscillator based on regenerative mode-locked fiber laser provides high-quality pulses over a repetition frequency range of 380 kHz. In the clock recovery experiment, a transform-limited pulse train is recovered from a 40 Gb/s signal, with pulse width of 7.2 ps, timing jitter (root-mean-square) of 152 fs, and super-mode suppression ratio over 60 dB. The loop is robust against pattern effect and amplitude fluctuation of input signal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1382 (2007)
Sensitivity Calculation of Disk-Type Fiber-Optic Sensor
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Taking the disk-type fiber optic accelerometer with a center-embedded and edge-fixed rigid mass block as an example, the stress and strain distribution on the flexural disk of the sensor is analyzed. The mathematical model for the acceleration sensitivity of the sensor is established based on Michelson interferometer pTaking the disk-type fiber optic accelerometer with a center-embedded and edge-fixed rigid mass block as an example, the stress and strain distribution on the flexural disk of the sensor is analyzed. The mathematical model for the acceleration sensitivity of the sensor is established based on Michelson interferometer principle, and the optimum sticking fiber disk dimension is discussed. Two sensors are fabricated and compared experimentally to verify the calculation model. With the above model, the sticking area and sensitivity calculating formulas are deduced under different boundary conditions. The result is useful for the design of disk-type fiber-optic sensors, such as accelerometer, pressure gauge and hydrophone..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1387 (2007)
100 km Fiber Bragg Grating Sensor System Based on Fiber Ring Laser and Optical Amplification
[in Chinese], [in Chinese], and [in Chinese]
A novel method based on a tunable fiber ring laser configuration with Er-doped fiber Raman hybrid amplification is proposed for performance enhancement of long-distance in-fiber Bragg grating (FBG) sensor systems to achieve quasi-distributed measurement. Such a method employs a tunable Er-doped fiber ring laser as lighA novel method based on a tunable fiber ring laser configuration with Er-doped fiber Raman hybrid amplification is proposed for performance enhancement of long-distance in-fiber Bragg grating (FBG) sensor systems to achieve quasi-distributed measurement. Such a method employs a tunable Er-doped fiber ring laser as light source. Dual-wavelength Raman fiber amplification is adopted for achieving low-noise bidirectional amplification of FBG signals, and two sections of EDFs, arranged in the fiber link remotely, are used for generation of amplified spantaneous emission with residual pump power to illuminate remotely-located FBG sensors and amplification of sensing signals, which makes the whole sensor system capable of achieving quite high signal-noise-ratio along ultra-long distance. Experimental results show that an excellent optical signal-noise-ratio of ～57dB has been achieved for a 100 km transmission distance with a low Er-doped fiber amplification pump power of ～40 mW at wavelength of 980 nm, a low Raman pump power of ～170 mW at wavelength of 1455 nm and a Raman pump power of ～2 W at wavelength of 1480 nm,leading to FBG-based sensing along ultra-long distance..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1393 (2007)
Self-Starting Nonreturn-to-Zero/Retun-to-Zero Signal, Optical, Electrical Clock Signal Generator and Data Format Conversion
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Utilizing two-light-sources-injection optoelectronic oscillator, including generator and phase modulator, nonreturn-to-zero (NRZ), return-to-zero (RZ) signal and optical, electrical clock signal are generated simultaneously. In this configuration, a coupled dual-loop is formed in optical domain for suppressing the sideUtilizing two-light-sources-injection optoelectronic oscillator, including generator and phase modulator, nonreturn-to-zero (NRZ), return-to-zero (RZ) signal and optical, electrical clock signal are generated simultaneously. In this configuration, a coupled dual-loop is formed in optical domain for suppressing the side modes in each loop without adding any active device. The phase modulator is employed to perform feedback modulation and data format conversion between NRZ and RZ with tunable duty ratio. Two lights work together for eliminating the unexpected frequency components introduced by optical coding signal. The experimental results at 10 Gb/s rate are demonstrated. The timing jitter of optical signal outputs is 637 fs and the duty ratio of converted RZ data is 33%. The electrical clock signal has high-quality spectrum at 10 GHz with a side mode suppression ratio of 58 dB, and a phase noise of -109 dBc/Hz at 10 kHz away from carrier..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1397 (2007)
Effect of Fiber Coupling on Photon-Detection Probability of Quantum Key Distribution Systems
[in Chinese], [in Chinese], and [in Chinese]
Global secure communication networks could become ture by use of quantum cryptography and satellite. However, satellite-to-ground quantum key distribution (QKD) systems by using of commercial single photon counting module (SPCM) are facing a challenge of spatial-light-to-multimode-fiber coupling on the receiver end. SpGlobal secure communication networks could become ture by use of quantum cryptography and satellite. However, satellite-to-ground quantum key distribution (QKD) systems by using of commercial single photon counting module (SPCM) are facing a challenge of spatial-light-to-multimode-fiber coupling on the receiver end. Spatial light-to-multimode-fiber coupling qualification puts strict restricts on pointing and tracking precision of satellite-to-ground QKD systems. It is indicated by theoretical analysis and quantificational calculation that QKD systems work normally with a high photon detection probability when the ratio of tracking error ε to beam divergence θdiv is below 0.5, and that QKD systems could work better when ε/θdiv≤0.1 with a quantum key rate of a few kb/s. Light with shorter wavelength is more favorable to spatial-light-to-multimode-fiber coupling, and to achieve a higher quantum key production rate as well..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1401 (2007)
Interrogation Techniques for Fiber Bragg Grating Sensor System Based on Active Closed Cavity
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel fiber Bragg grating (FBG) sensor system with an active closed cavity is proposed according to the principle of fiber loop mirror (FLM) based on 3 dB wideband coupler fabricated by fused biconical taper technique. Ten cascaded wavelength-division-multiplexed (WDM) FBG sensors are fabricated in the FLM acting as A novel fiber Bragg grating (FBG) sensor system with an active closed cavity is proposed according to the principle of fiber loop mirror (FLM) based on 3 dB wideband coupler fabricated by fused biconical taper technique. Ten cascaded wavelength-division-multiplexed (WDM) FBG sensors are fabricated in the FLM acting as an end mirror of a closed cavity resonator. Active interrogation techniques are realized by controlling the applied voltage of the insert tunable Fabry-Pérot filter of the cavity and realizing wavelength scanning. The unbalanced Michelson interferometer transforms the wavelength-shift signal induced by the measured strain into phase-shift signal, and the demodulation is achieved. The experimental sensor sensitivity, 1.5835 °/10-6ε matches the predicted value (1.6662 °/10-6) basically..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1405 (2007)
Polarization-Dependent Loss of Long-Period Fiber Grating Fabricated by Dual-Side Exposure Method
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The polarization-dependent loss (PDL) of long-period fiber gratings (LPFGs) etched by high-frequency CO2 laser pulses through single-side and dual-side exposure technologies was investigated. Long-period fiber gratings induced by the single-side exposure method depend greatly on the polarization state of incident lightThe polarization-dependent loss (PDL) of long-period fiber gratings (LPFGs) etched by high-frequency CO2 laser pulses through single-side and dual-side exposure technologies was investigated. Long-period fiber gratings induced by the single-side exposure method depend greatly on the polarization state of incident light and have large polarization-dependent loss due to the asymmetry of refractive index profile in its cross section. A new dual-side exposure method is applied in long-period fiber gratings writing process to reduce polarization-dependent loss by uniforming the refractive index profile in the fiber cross section. Experimental results show that polarization-dependent loss of the long-period fiber gratings drops down to 0.42 dB by using dual-side exposure technology compared with 1.24 dB by the single-side exposure method. The dual-side exposure technique overcomes the influence of polarization state of incident light and can produce low-polarization-dependent loss long-period fiber gratings which can be widely used in optical fiber communication and sensing systems..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1409 (2007)
Influence of Scene Structure and Noise on Precision of Correlating Hartmann-Shack Wavefront Sensing
[in Chinese], [in Chinese], and [in Chinese]
Influence of the observed-scene structure and noise on the precision of correlating Hartmann-Shack wavefront sensing is systematically analyzed, where the scene structure is described with spatial spectrum, and the signal-noise-ratio (SNR) is described with the ratio of the root-mean-square (RMS) of image grey varianceInfluence of the observed-scene structure and noise on the precision of correlating Hartmann-Shack wavefront sensing is systematically analyzed, where the scene structure is described with spatial spectrum, and the signal-noise-ratio (SNR) is described with the ratio of the root-mean-square (RMS) of image grey variance to the root-mean-square of noise. Theoretical analysis shows that the subpixel interpolation error of correlation function at peak value of two subimages is equal to the weighted average of the correlation function interpolation error (CFIE) at peak value of their discrete frequency components. With the same power, the weighting coefficient of the low-frequency components is less, and the weighting coefficient of the high-frequency components is related with the subpixel shifts. Statistical simulations of one-dimensional narrow-band images show that, in zero-noise case, the CFIEs of the frequency components near the zero frequency or Nyquist frequency are relatively larger compared with the middle-frequency components. And the influence of noise on the high-frequency components is lower than that on the low-frequency components. Simulations of broad-band images with a typical spectrum and 32×32 pixels show that, The calculating error of sub-image shift is 0.03～0.11 pixels under the signal-to-noise ratio (SNR) of 2∶1, which only has a small increase in error compared with the zero-noise case..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1414 (2007)
Multi-Spectral Image Fusion Based on Two-ChannelNon-Separable Additive Wavelets
[in Chinese], and [in Chinese]
A construction method of non-separable wavelets with dilation matrix of [1,1;1,-1] is proposed and applied to the fusion of multi-spectral images and panchromatic images with high resolution. A construction method of two-channel symmetric non-separable wavelets filter bank is also proposed, and non-separable wavelets 6A construction method of non-separable wavelets with dilation matrix of [1,1;1,-1] is proposed and applied to the fusion of multi-spectral images and panchromatic images with high resolution. A construction method of two-channel symmetric non-separable wavelets filter bank is also proposed, and non-separable wavelets 6×6 filter banks with compact support, symmetry, orthogonality are designed. The images are discomposed and reconstructed through additive wavelet mode with low-pass filters of the above filter bank. ETM+ images and other multi-spectral images and panchromatic images with high resolution are fused and studied through NAWS, AWRGB and NAWL wavelet modes. The experimental results show that this method has well fusion performance for multi-spectral images and panchromatic images with high resolution. Compared with other fusion methods, the proposed method preserves the spectral information of multi-spectral images and the high resolution of panchromatic images. It overcomes the shortage of traditional vector product wavelet fusion method, i.e. being incapable of get images with high resolution, and saves computation time..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1419 (2007)
Imaging Characteristics of Wavefront Coding Systems within Spatial Domain
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Applying the wavefront coding technique to optical system can greatly increase the depth of focus and correct the focus-related aberrations. While most coventional imaging characteristics analysis of the wavefront coding system is carried out within spatial-frequency domain, here the analysis within spatial domain was Applying the wavefront coding technique to optical system can greatly increase the depth of focus and correct the focus-related aberrations. While most coventional imaging characteristics analysis of the wavefront coding system is carried out within spatial-frequency domain, here the analysis within spatial domain was applied. The approximate expression of point spread function for the wavefront coding system with cubic phase mask was derived with the stationary phase method, based on which the sensitivities of the wavefront coding system to defocus, astigmatism and coma were analyzed, and the boundary, bandwidth and oscillations of the point spread function were described. A further insight into the imaging characteristics of the wavefront coding system was acquired within spatial domain..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1425 (2007)
Vibration Menasurement Based on Moderate Optical Feedback Self-Mixing Interference
[in Chinese], [in Chinese], and [in Chinese]
Optical feedback self-mixing interferometry is an emerging sensing and measurement technique, which is quite different with traditional double-beam interferometry. To perform precision vibration measurement under the condition of moderate optical feedback, a vibration measurement method is proposed based on moderate opOptical feedback self-mixing interferometry is an emerging sensing and measurement technique, which is quite different with traditional double-beam interferometry. To perform precision vibration measurement under the condition of moderate optical feedback, a vibration measurement method is proposed based on moderate optical feedback self-mixing interference. Based on the analysis of the optical feedback self-mixing inteference signal fringes, it is found that saw-like fringes in the self-mixing signal waveforms can be observed by properly choosing the optical feedback level and line width enhancement factor of semiconductor laser. With the saw-like fringe not only the vibration amplitude can be measured, but the movement direction can also be determined. The proposed measurement is based on the analysis of saw-like fringes with the following two steps. Firstly, rough measurement of displacement is carried out by counting the fringe numbers with the resolution of half wavelength. Then based on the studies of fractional fringe structure under modulate optical feedback, a linear formula for displacement within half wavelength is derived, and precise displacement measurement is realized. Computer simulations show that the proposed technology is able to achieve high-resolution and large-range measurement of vibration amplitude..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1430 (2007)
Neural Network Applied to Three-Dimensional Measurement of Complex Objects
[in Chinese], and [in Chinese]
The neural network has been introduced into the reconstruction of the complex three-dimensional (3D) object based on structured light projection. In the network method, the neural network with powerful function of approximation is used to get the continuous approximate function of the discrete fringe pattern. The measuThe neural network has been introduced into the reconstruction of the complex three-dimensional (3D) object based on structured light projection. In the network method, the neural network with powerful function of approximation is used to get the continuous approximate function of the discrete fringe pattern. The measured object can be reconstructed by dealing with the approximate function and drawing phase distribution of the object. As a result, the network method based on structured light projection need only one deformed fringe pattern to reconstruct the tested object. Compared with the Fourier transform profilometry (FTP), the neural network method without filtering process does not lose high frequency of the measured object. So it has large space bandwidth product and high sensitivity can given out the detail precisely. Therefore, this method performs better than FTP in the three-dimensional shape measurement of complex objects. Moreover, compared with FTP, the network method can demodulate more useful phase from the fringe pattern with shadow. Computer simulations and experiment validate the feasibility of this method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1435 (2007)
Distortion Measurement and Calibration Technology for CCD Camera System Based on New Target Board
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The influence of testing map on distortion measurement and calibration is extensively studied. A so called “one target distortion testing method” is presented for distortion measurement and calibration. The distorted image of the self-designed and fabricated “integrated spot array target board” is recorded. The positioThe influence of testing map on distortion measurement and calibration is extensively studied. A so called “one target distortion testing method” is presented for distortion measurement and calibration. The distorted image of the self-designed and fabricated “integrated spot array target board” is recorded. The position of distorted points is determined by image processing, and compared with the ideal points position. The position relation between distorted points and ideal points is established by polynomial model. The position of ideal points is obtained by ideal imaging. Then polynomial coefficients of the model are computed from the least squares method. While corresponding the distorted points to ideal points, the whole CCD camera system's distortion is calibrated. The integrated spot array target board consists of gray spots and black interval belts, and makes it convenient to mark the spots in sequence and correspond the distorted points to the ideal points. The distortion of wide-angle CCD camera system with focal length of 2.6 mm is repeatedly measured and calibrated, and the calibrating precision is within 0.3%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1440 (2007)
Properties Analysis for Reflection-Type Filter Composed of Microring Resonator Array and Mach-Zehnder Interferometer
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The theoretical analysis is presented for the wavelength-selective reflection-type filter realized by combination of microring resonator array and Mach-Zehnder interferometer. By introducing the series-cascaded two kinds of four-port network, the general formulas are derived with the transfer matrix method, and expliciThe theoretical analysis is presented for the wavelength-selective reflection-type filter realized by combination of microring resonator array and Mach-Zehnder interferometer. By introducing the series-cascaded two kinds of four-port network, the general formulas are derived with the transfer matrix method, and explicit expressions for the power reflection coefficients of single-ring and three-ring structures are given. The changes of the reflection spectrum shapes are computed for different values of coupling coefficients by the transmission function matrices, and detailed analysis and discussions are given for the reason. For the three-ring structure, the influences of transmission loss on the power reflectivity of resonant peaks are simulated. The simulation results show that: when the ring-bus and ring-ring coupling ratios are selected properly, this device can be used as a reflection-type filter in dense wavelength division multiplexing (DWDM) system and an end mirror for lasers; the degradation of the peak reflectivity value with the transmission loss increase depends on the values of selected coupling ratios..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1443 (2007)
Formation and Properties of Glass in Ternary TeO2-Nb2O5-YF3System
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The ternary TeO2-Nb2O5-YF3 glass was synthesized and the formation range of TeO2-Nb2O5-YF3 glass system was investigated. The density, refractive index, differential thermal property (DTA), Raman spectra, UV absorption spectra and infrared transmission spectra of the samples were tested. The effects of composition contThe ternary TeO2-Nb2O5-YF3 glass was synthesized and the formation range of TeO2-Nb2O5-YF3 glass system was investigated. The density, refractive index, differential thermal property (DTA), Raman spectra, UV absorption spectra and infrared transmission spectra of the samples were tested. The effects of composition content change on the structure and infrared transmission properties of glasses were investigated by spectra analysis. The results show that the glass forming ability and thermal stability of the ternary TeO2-Nb2O5-YF3 glass are good. The presented oxyhalide tellurite glass exhibits a high transmissivity (80%) in the mid-infrared regions (3～5 μm). There is no evident [OH] absorption bands in the range of 2.8～3.3 μm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1449 (2007)
Organic Light-Emitting Devices Based on Novel Hole Transport Layer
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Double-layer organic light-emitting devices were fabricated by conventional vacuum deposition method using 2,7-bis (p-methoxyphenyl-m′-tolylamino)-9,9-dimethylfluorene (TPF-OMe) and N, N′-biphenyl-N, N′-bis-(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD) as hole transport layer (HTL), respectively, and tris(8-hydroxyDouble-layer organic light-emitting devices were fabricated by conventional vacuum deposition method using 2,7-bis (p-methoxyphenyl-m′-tolylamino)-9,9-dimethylfluorene (TPF-OMe) and N, N′-biphenyl-N, N′-bis-(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD) as hole transport layer (HTL), respectively, and tris(8-hydroxyquinolinato) aluminum (Alq3) as electron transport and light emitting layer (ETL and EML). The devices consisting of TPF-OMe as HTL show higher current density but lower luminous efficiency, and a green-blue emission at 516 nm, CIE (0.30,0.53), which is Alq3 electroluminescence spectrum. The devices with the structure of ITO/TPF-OMe (40 nm)/ 2,9-dimethyl-4,7- dipheny 1-1,10-phenanthroline (bathocuproine or BCP) (5 nm)/Alq3 (35nm)/Mg∶Ag (300 nm) was also fabricated, which showed blue light emission of TPF-OMe at the peak of 414 nm, CIE coordinates of (0.20, 0.24), current density of 1137 mA/cm2 and luminance of 900 cd/m2 at 15 V, the maximum luminous efficiency 0.11 lm/W at 3 V. Also, the devices based on TPF-OMe has 20 ℃ higher thermal stability compared with that using TPD as HTL, which may be caused by the 19 ℃ higher glass-transition temperature (Tg) of TPF-OMe than TPD material..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1455 (2007)
Achromatic Phase Shifter Implemented in Full-Field Optical Coherence Tomography
[in Chinese], and [in Chinese]
Theoretical model of an achromatic phase shifter based on a rotating half-wave plate and its implementation in a full-field optical coherence tomography (OCT) system are proposed for rapid and high-resolution OCT imaging. The phase shifter that is almost independent of the wavelength over a broad range can provide phasTheoretical model of an achromatic phase shifter based on a rotating half-wave plate and its implementation in a full-field optical coherence tomography (OCT) system are proposed for rapid and high-resolution OCT imaging. The phase shifter that is almost independent of the wavelength over a broad range can provide phase shift at eight times of rotating angle of the half-wave plate. Conventional monochromatic phase-shifting algorithms can thus be adopted without systematic errors. Numerical analysis on phase shifting error and amplitude ratio between orthogonal polarization components versus wavelength over a range of 240 nm for nominal phase shifts required for the revised Carré algorithm and three-step phase-shifting algorithm respectively is conducted. The results demonstrate increased phase shift error and increased fluctnation of amplitude ratio for larger nominal phase shift. The full-field OCT system with the proposed achromatic phase shifter has several advantages compared with previous system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1460 (2007)
Monte Carlo Simulation of Polarization Gating for Superficial Tissue Detection
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Previous studies have demonstrated that the techniques of polarization and oblique incidence can effectively suppress the scattered light from deep layer, thus providing feasible methods to detect optical properties of superficial tissue. Monte Carlo simulation is used to study their mechanism. The effects of optical pPrevious studies have demonstrated that the techniques of polarization and oblique incidence can effectively suppress the scattered light from deep layer, thus providing feasible methods to detect optical properties of superficial tissue. Monte Carlo simulation is used to study their mechanism. The effects of optical properties and incident angle on detection depth are investigated respectively. It is found that anisotropy factor and incident angle affects the detection depth much. While for the cases of small anisotropy (<0.8) or large incident angle (>1.4 rad), detection depth can be constrained in the depth of less than 2 fold of mean free path. The techniques of polarization and oblique incidence can effectively reduce scattering times and penetration depth of detected photons, which indicates that it can effectively differentiate signal from superficial tissue and remove background signal from underlying tissue through combining these two techniques..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1465 (2007)
Fourier-Domain Optical Coherence Tomography Based on Sinusoidal Phase Modulation
[in Chinese], [in Chinese], and [in Chinese]
A Fourier-domain optical coherence tomography based on sinusoidal phase modulation is presented. The complex Fourier domain interference fringe is reconstructed by detecting its real and imaginary components by sinusoidal phase modulating interferometry. After inverse Fourier transform of complex interference fringes, A Fourier-domain optical coherence tomography based on sinusoidal phase modulation is presented. The complex Fourier domain interference fringe is reconstructed by detecting its real and imaginary components by sinusoidal phase modulating interferometry. After inverse Fourier transform of complex interference fringes, the complex conjugate mirror images, direct current background and self-coherent noise in the Fourier-domain optical coherence tomography are eliminated. The tomographic experiment on glass sample is carried out. The result indicates that the range of imaging depth is doubled, and the Fourier domain optical coherence tomography for full-depth detection is realized..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1470 (2007)
Property of Ultrashort Electromagnetic Pulse Propagation in Metamaterial
[in Chinese], and [in Chinese]
By incorporating the dispersive permeability of metamaterial into the nonlinear polarization component, and borrowing the derivation way of nonlinear pulse propagation equation in ordinary material, a general nonlinear propagation equation for ultrashort pulse in metamterial is obtained. It is shown that for Drude dispBy incorporating the dispersive permeability of metamaterial into the nonlinear polarization component, and borrowing the derivation way of nonlinear pulse propagation equation in ordinary material, a general nonlinear propagation equation for ultrashort pulse in metamterial is obtained. It is shown that for Drude dispersive model, the dispersive permeability results in a self-steepening parameter which can be negative, positive or zero depending on the central frequency of the pulse, and a series of high-order nonlinear dispersion terms in the propagation equation. Furthermore, the propagation equation is analyzed by using the moment method, an explicit expression for energy conservation for the propagation equation is obtained, and unique propagation properties of ultrashort pulse in metamaterials are disclosed. It is found that due to the second-order nonlinear dispersion, the characteristic parameters of the ultrashort pulse, including energy, frequency shift, duration, center position, and chirp, all oscillate with propagation distance..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1475 (2007)
A Novel All-Optical Accurate Synchronization for Broadband Optical Parametric Chirped Pulse Amplification
[in Chinese], [in Chinese], and [in Chinese]
The generation of direct current background-free pulses at 1064 nm that are accurately synchronized with femtosecond pulses at 800 nm is reported by use of a continuous-wave diode laser seeded noncollinear optical parametric amplification pumped by frequency-doubled femtosecond laser at 800 nm. The experimental resultsThe generation of direct current background-free pulses at 1064 nm that are accurately synchronized with femtosecond pulses at 800 nm is reported by use of a continuous-wave diode laser seeded noncollinear optical parametric amplification pumped by frequency-doubled femtosecond laser at 800 nm. The experimental results show that the laser pulses are quite qualified as the seed pulses of the pulsed laser amplification operating at 1064 nm due to their high pulse energy and spatial beam quality. An accurate all-optical synchronization is realized between pump and signal beams in an optical parametric chirped pulse amplification system just through a single-stage compact noncollinear optical parametric amplifier..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1481 (2007)
Self-Bending Effect of Spatial Soliton in Photorefractive Medium
[in Chinese], [in Chinese], and [in Chinese]
Internal charge drift is induced by applying an external electric field on the photorefractive crystal. The drifted charges may lead to the diffusion of spatial charges which accounts for the nonlocal nonlinearity. The propagation of spatial soliton supported in the photorefractive medium with drift and diffusion nonliInternal charge drift is induced by applying an external electric field on the photorefractive crystal. The drifted charges may lead to the diffusion of spatial charges which accounts for the nonlocal nonlinearity. The propagation of spatial soliton supported in the photorefractive medium with drift and diffusion nonlinearity is investigated theoretically. The effective “acceleration” of soliton is derived by analyzing the dynamics of the (1+1) dimensional spatial soliton in this kind medium with equivalent-particle approximation methods. The parameters of input soliton and nonlocality determine the effective acceleration of soliton. The results can be used to calculate the propagation trajectory of solitons in a certain parameter range. We also simulate the propagation of soliton under perturbation of nonlocal nonlinearity. The theoretical analysis results are in good agreements with the numerical simulation results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1485 (2007)
Optical Throughput of Modified Sagnac Imaging Interferometer
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
According to Fresnell's formula, the coefficients of reflection and transmission of every interface of super-wide-angle Sagnac interferometer (SASI) are calculated. The exit solid angle and transmissivity are deduced, and the expression of luminous flux is derived. The luminous flux optical throughput is calculatedAccording to Fresnell's formula, the coefficients of reflection and transmission of every interface of super-wide-angle Sagnac interferometer (SASI) are calculated. The exit solid angle and transmissivity are deduced, and the expression of luminous flux is derived. The luminous flux optical throughput is calculated with the parameters such as sizes and reflective index of glass arms of ZBaF17 and QF14 in a modified super-wide-angle Sagnac interferometer. The solid angle is 1.7316×10-4 rad, the emergent intensity is about 0.4397 of incidence, with AΩ=0.4×10-4 cm2·sr..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1490 (2007)
Design of Optical Acceleration Sensor Based on Diffractive Micro Lens
[in Chinese], [in Chinese], and [in Chinese]
A novel optical acceleration sensor based on a Fresnel diffractive micro lens is presented. It can effectively solve the low immunity of inertial sensors widely used in navigation system towards electro magnetic interference and electro magnetic pulse. A reflecting membrane is parallelly located behind the diffractive A novel optical acceleration sensor based on a Fresnel diffractive micro lens is presented. It can effectively solve the low immunity of inertial sensors widely used in navigation system towards electro magnetic interference and electro magnetic pulse. A reflecting membrane is parallelly located behind the diffractive micro lens and its displacement is determined by the acceleration. Acceleration is calculated by measuring variational light intensity at the frontal focal point of the lens. The principles of the sensor and its dynamic system are described, and both the diffractive micro lens and the micro spring-mechanical structure of the dynamic system were designed and fabricated. Moreover, the performance and error of the sensor were analyzed. The results of proof-of-principle experiments indicate that the principle of the novel sensor is correct and the sensor has merits of simple structure and high sensitivity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1494 (2007)
Twin Defect Modes in One-Dimensional Photonic Crystals with Defect Layers of Multiple Single-Negative-Materials
[in Chinese], and [in Chinese]
The defect modes in one-dimensional photonic crystals containing defect layers of multiple single-negative materials are analyzed. The photonic crytals are stacked alternately with single-negative-permittvity and single-negative-permeability media with periodic defect layers. Twin defect modes are found inside the photThe defect modes in one-dimensional photonic crystals containing defect layers of multiple single-negative materials are analyzed. The photonic crytals are stacked alternately with single-negative-permittvity and single-negative-permeability media with periodic defect layers. Twin defect modes are found inside the photonic gap with zero effective phase. By varying the defect number or the thicknesses of the defect layers, the frequency interval of the defect modes can be changed, but the number of the defect modes remains two. The two defect modes inside the zero-effective-phase gap are insensitive to incident angle;the normalized frequency shift of the defect modes is always less than 0.03 as the incident angle varies. Moveover, the electric fields at the frequencies of the defect modes are strongly localized at the interfaces between defect layers and periodic structures..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1498 (2007)
Experiments and Theoretical Analyses of Non-Diffracting Beams Interference
[in Chinese], and [in Chinese]
The interference pattern and locus of interference fringes of two non-diffracting beams are analyzed. Two non-diffracting beams are generated when an axicon is illuminated by two coherent beams, which are produced by two pinholes illuminated by a monochromatic wave. Based on the non-diffracting property of an axicon inThe interference pattern and locus of interference fringes of two non-diffracting beams are analyzed. Two non-diffracting beams are generated when an axicon is illuminated by two coherent beams, which are produced by two pinholes illuminated by a monochromatic wave. Based on the non-diffracting property of an axicon in oblique illumination, the interference field is the linear superposition of each non-diffracting field of non-diffracting beam. The locus of interference fringes is analyzed to be hyperbola according to the zero-point formula of zero-order Bessel function. Results show that the distance of the two centers of interference field is proportional to the distance of the two pinholes and the distance between the axicon and interference field. The experimental results are in good agreement with the numerical simulation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1503 (2007)
Quantum Information Transfer Via Multi-Photon Interaction
[in Chinese], [in Chinese], and [in Chinese]
According to the complete quantum theory, the process of multi-photon interaction in the multi-atom-cavity system was studied. The universal evolution equations of the system were shown under different states. It is found that the quantum entanglement information can be transferred by using the interaction process. WheAccording to the complete quantum theory, the process of multi-photon interaction in the multi-atom-cavity system was studied. The universal evolution equations of the system were shown under different states. It is found that the quantum entanglement information can be transferred by using the interaction process. When the time of atoms interacting with cavities is controlled, namely, the atoms pass the cavity field with special speeds, the quantum entanglement information can be obtained via ground state atoms interacting with the cavity field carrying entanglement information, whereas the quantum entanglement information stored in the atoms can also be transferred to the cavity field of vacuum state. And the ground atoms as “flying qubit” can transmit the quantum entanglement information from a cavity field to another. The conclusions mentioned above are fit for the interaction among photons..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1508 (2007)
Debye Series of Gaussian Beam Scattering by a Multi-Layered Sphere
[in Chinese], [in Chinese], and [in Chinese]
On the basis of the generalized Lorenz-Mie theory, a new method to study Gaussian beam scattering by a multi-layered sphere is presented by the formula of the Debye series decomposition for scattering coefficients. The results calculated by this method and by the generalized Lorenz-Mie theory agree well. The scattered On the basis of the generalized Lorenz-Mie theory, a new method to study Gaussian beam scattering by a multi-layered sphere is presented by the formula of the Debye series decomposition for scattering coefficients. The results calculated by this method and by the generalized Lorenz-Mie theory agree well. The scattered field distribution in the far-zone of a multi-layered sphere illuminated by Gaussian beam is simulated and the interference intensity distribution of mixed order rainbows is separated efficiently. The refractive index profile of the multi-layered sphere is exponential versus the radial position. The intensity distribution of the twin first-order rainbow and the Airy structure of each layer by a two-layered sphere are simulated. At last, the influence of incident position and beam waist on scattering intensity distribution is discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1513 (2007)
Linear and Nonlinear Optical Properties of Two PPV Derivatives
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The effect of side chains with different length on the optical properties of two PPV derivatives, poly (2,5-dioctyloxy-1,4-phenylenevinylene) and poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene), was investigated by absorption spectroscopy, fluorescence spectroscopy and picosecond Z-scan technique. The oThe effect of side chains with different length on the optical properties of two PPV derivatives, poly (2,5-dioctyloxy-1,4-phenylenevinylene) and poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene), was investigated by absorption spectroscopy, fluorescence spectroscopy and picosecond Z-scan technique. The optical properties of two derivatives were discussed using the theories of π-electron conjugated structure and resonant/non-resonant enhancement, respectively. The obtained results demonstrated that the absorption and fluorescence emission bands of MEH-PPV shift towards the long wavelength direction compared with the counterparts of DO-PPV. Furthermore, the side chains also affect the third-order nonlinear susceptibilities χ(3) of PPV polymers. Under the resonant excitation, the third-order nonlinear susceptibility χ(3) of MEH-PPV at 532 nm is two orders of magnitude larger than that of DO-PPV, and reached a maximum of 9.30×1010 esu..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1519 (2007)
Lattice Vibrational Spectrum of Yb∶Y3Al5O12Crystals
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Y3Al5O12 (YAG) and Yb∶Y3Al5O12 (Yb∶YAG) single crystals with Yb3+ doping atomic number fraction of 5%, 10%, 15%, 20%, 25%, 50%, and 100% were grown by the Czochralski method. The effects of Yb3+ doping level on the Raman spectra were studied. There were little abrupt change of the vibration modes and little change of tY3Al5O12 (YAG) and Yb∶Y3Al5O12 (Yb∶YAG) single crystals with Yb3+ doping atomic number fraction of 5%, 10%, 15%, 20%, 25%, 50%, and 100% were grown by the Czochralski method. The effects of Yb3+ doping level on the Raman spectra were studied. There were little abrupt change of the vibration modes and little change of the crystal structure with the increase of Yb3+ doping level in Yb∶YAG crystals; but the fullwidth at half maximum of absorption peak centered at 370 cm-1 and 785 cm-1 increased with the increase of Yb3+ doping level. The results show that Yb3+ doping level influences the lattice, symmetry and fluorescence lifetime of Yb∶YAG crystals and this may influence the spectrum and lasing properties of the crystals..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1525 (2007)
Reflectivity of Au Film on K9 and Quartz Substrate in Vacuum Ultraviolet
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Au films of various thicknesses are fabricated by ion-beam sputtering with different coating parameters on quartz and K9 substrate which are processed with different cleaning procedures. Their reflectivity is measured continuously in a broad vacuum ultraviolet range. It is indicated that the auxiliary ion-beam source aAu films of various thicknesses are fabricated by ion-beam sputtering with different coating parameters on quartz and K9 substrate which are processed with different cleaning procedures. Their reflectivity is measured continuously in a broad vacuum ultraviolet range. It is indicated that the auxiliary ion-beam source and the film thickness impact significantly on the reflectivity. Substrate material and cleaning procedure also affect reflectivity of Au film to some extent. Ion-beam bombardment of substrate before deposition can significantly enhance the reflectivity and adhesion of films. The optimal film thickness for the highest reflectivity connects closely with substrate material and coating techniques. For quartz substrate processed by ion bombardment pre-deposition, the optimal film thickness is about 30 nm, and the reflectivity of quartz is higher than K9. The use of auxiliary ion beam source influences the optimal film thickness for the highest reflectivity, and the influence is larger for K9 substrate..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 8, 1529 (2007)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20