Contents
2005
Volume: 25 Issue 6
28 Article(s)
Export citation format
Atmospheric Optics and Oceanic Optics
Study of the Detection Mode of Upper Atmospheric Wind Field Based on Lorentzian Profile Aurora
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Based on Lorentzian profile auroral theoretical formula of interference intensity, modulation and optical path difference (OPD), measurement of upper atmospheric wind field can be achieved. Four interference intensities are obtained by “four-intensity way” to detect upper atmosphere wind speed, temperature and pressureBased on Lorentzian profile auroral theoretical formula of interference intensity, modulation and optical path difference (OPD), measurement of upper atmospheric wind field can be achieved. Four interference intensities are obtained by “four-intensity way” to detect upper atmosphere wind speed, temperature and pressure based on Lorentzian profile. The modified Sagnac interferometer (MSI) has been put forward to substitute Michelson interferometer for wind field; the benchmark optical path difference (OPD) formula of MSI has been presented. The technique of coating pyramid prism (CPP) has been put forward too. By the technique of coating pyramid prism's anti-reflection coating for three faces, four intensities can been obtained through stepped optical path difference of λ/4 at the same time. A simulation test has made: when the symmetrical light of Kr 557.0 nm to the two-faces CPP's vertex of 60° angle, there are two imager speckle patterns on the CCD camera of 768×576, copying the two imager speckle patterns there are four interference intensities in a periods, so Lorentzian profile auroral upper atmospheric wind field can be achieved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 721 (2005)
Fiber Optics and Optical Communications
Reconstruction of Refractive Index Profile of Diffused Planner Waveguide by Iteration Method
[in Chinese], and [in Chinese]
An iteration method is presented to reconstruct planar waveguide refractive index profile from mode indices spectra. In the current method, a numerical process is employed to solve the Helmholtz equation, the “turning point” positions of all the propagation modes are adjusted in sequence from the lowest to the highest An iteration method is presented to reconstruct planar waveguide refractive index profile from mode indices spectra. In the current method, a numerical process is employed to solve the Helmholtz equation, the “turning point” positions of all the propagation modes are adjusted in sequence from the lowest to the highest by iteration, and repetitions of the iteration are performed to eliminate the effect of refractive index profile variation beyond each “turning point” on the corresponding “turning point” position. The convergence of “turning point” position over iteration in this process is briefly illustrated by means of the WKB principle. A demonstrative reconstruction is made for a planar waveguide with exponential refractive index profile, and results show that the current method can be used to reconstruct planar waveguide refractive index profile with high accuracy. Analysis indicates: this iteration method is expected to be superior in both self-consistence and accuracy to the inverse WKB method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 726 (2005)
Theoretical and Experimental Study on White-Light Interferometric Sensing Network with Double-Ring Topology
[in Chinese], and [in Chinese]
A white-light interferometric fiber optical sensing network based on the double-ring topology is demonstrated, which can be applied to the measurements of quasi-distributed strain and temperature in a smart structure. In order to increase the multiplexing capacity, decrease the measurement cost of each single point senA white-light interferometric fiber optical sensing network based on the double-ring topology is demonstrated, which can be applied to the measurements of quasi-distributed strain and temperature in a smart structure. In order to increase the multiplexing capacity, decrease the measurement cost of each single point sensor, and improve the ability to resist destruction of the sensor network by resorting to the double-port inquiring technology, the double-ring fiber optical sensing network based on the space division multiplexing (SDM) is further developed. The low-coherent multiplexing principle in the double-ring network structure is analyzed. And based on the optical path matching condition of space division multiplexing, the intensity characteristic of the interference signal in the sensor is deduced. The characteristics of double-ring sensing network connecting 9 sensors and its property of resisting destruction are verified by experiments, and the results of experiments are analyzed and discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 731 (2005)
Expanded Core Fiber Principle and Its Application in Optical Device Coupling
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Two kinds of expanded core fibers (ECF) are fabricated, one is single-mode fiber cascaded gradual index (GI) fiber and the other is thermally diffused expanded core fiber (TEC). The testing shows that ECF can reduce loss in fiber-to-fiber coupling and increase the misalignment tolerance greatly, so that it make the aliTwo kinds of expanded core fibers (ECF) are fabricated, one is single-mode fiber cascaded gradual index (GI) fiber and the other is thermally diffused expanded core fiber (TEC). The testing shows that ECF can reduce loss in fiber-to-fiber coupling and increase the misalignment tolerance greatly, so that it make the alignment and adjustment easier than normal single mode fiber(SMF). The transmission characteristics of the two kinds of ECF are studied and the probable use in optical devices such as connector, isolator and optical filter working as collimator are analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 737 (2005)
The Combination of Beams between Single-Mode and Multimode Fibers in Fused Coupler
[in Chinese], [in Chinese], and [in Chinese]
As a splitter, the common fiber coupler has a low insert loss, while as a combiner it exhibits high loss. In order to obtain the combining beams with low insert loss, a new configuration coupler is presented, which is consituted with a single-mode fiber and a multimode fiber. The working principle is theoretically analAs a splitter, the common fiber coupler has a low insert loss, while as a combiner it exhibits high loss. In order to obtain the combining beams with low insert loss, a new configuration coupler is presented, which is consituted with a single-mode fiber and a multimode fiber. The working principle is theoretically analyzed by the coupling wave equation and the coupling procedure is simulated by the computer. The coupler was made with a single-mode fiber and a multimode fiber by fused-taper technology. The result agreed well with the simulating drawing. The combining of two beams is realized. The coupling ratio of each arm is more than 90%. As a combiner, with low insert loss, this component could be used in optical communication and double cladding fiber laser to improve coupling efficiency of pumping light..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 743 (2005)
Studies on Supercontinuum Generation in Dispersion Shifted Fiber by Using Mode-Locked Fiber Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The 20 dB-bandwidth of 125 nm covering the whole C, L bands and part of S band of supercontinuum (SC) in a 4.2 km dispersion-shifted fiber (DSF) was obtained in the experiment, which was based on the actively mode-locked erbium-doped fiber laser (AMLFL) with the repetition rate of 10 GHz and the pulse duration of 7.97 The 20 dB-bandwidth of 125 nm covering the whole C, L bands and part of S band of supercontinuum (SC) in a 4.2 km dispersion-shifted fiber (DSF) was obtained in the experiment, which was based on the actively mode-locked erbium-doped fiber laser (AMLFL) with the repetition rate of 10 GHz and the pulse duration of 7.97 ps. The dispersion-shifted fiber (DSF) was pumped by the output pulses from the AMLFL without being compressed. In a DSF, the supercontinuum results from combined interaction of nonlinear effects including self-phase modulation (SPM) and cross-phase modulation (XPM). The influences of peak powers and wavelengths of pumping pulse on supercontinuum (SC) spectrum were experimentally investigated. It is clear that the generated supercontinuum could be broadened further when the pump pulse peak power is increased; The broader supercontinuum could be got by optimization of pump wavelength; At the same time, the characteristics of pulses which are filtered out from supercontinuum spectrum by tunable filter with 0.4 nm bandwidth were studied. The stable, narrow optical pulses with pulse-width of 8.90～9.80 ps and time-bandwidth product of 0.44～0.49 were filtered out from the supercontinuum at different wavelengths..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 746 (2005)
Analysis of Coupling Power for Fused-Biconical 2×6 Single-Mode Optical Fiber Coupler
[in Chinese], [in Chinese], and [in Chinese]
Based on linear couple mode equation, propagation constants, eigenmodes and power coupling characteristics of 2×6 fused-biconical single-mode fiber coupler with weak fusion and weak couple were derived. The two layers 2×6 fiber coupler was fabricated by fused-biconical method. Experimental results obtained abBased on linear couple mode equation, propagation constants, eigenmodes and power coupling characteristics of 2×6 fused-biconical single-mode fiber coupler with weak fusion and weak couple were derived. The two layers 2×6 fiber coupler was fabricated by fused-biconical method. Experimental results obtained about spectral responses of the coupler are in good agreement with the theoretical results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 751 (2005)
Image Processing
Multi-Focus Image Fusion Based on Non-Negative Matrix Factorization
[in Chinese], and [in Chinese]
A new method based on the sharpness-constrained non-negative matrix factorization (SNMF) technique was presented for multi-focus images fusion. An new objective function was defined to impose sharpness constraint, in addition to the non-negativity constraint in the standard NMF. An algorithm was presented for SNMF. TheA new method based on the sharpness-constrained non-negative matrix factorization (SNMF) technique was presented for multi-focus images fusion. An new objective function was defined to impose sharpness constraint, in addition to the non-negativity constraint in the standard NMF. An algorithm was presented for SNMF. The local feature based representation could be obtained by choosing suitable dimension of the feature subspace in NMF. It was pointed out that when using SNMF, if the dimension of the feature subspace was set to 1, the resulted feature base was just the fusion result of the original input images. The feature base obtained included the global feature of the original images. Experimental results were presented to compare SNMF with wavelet transform and Laplacian methods for image fusion, which demonstrates advantages of SNMF in preserving the global feature information..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 755 (2005)
A New Tracking Method of Dynamic Contour Based on Image Fusion
[in Chinese], [in Chinese], and [in Chinese]
Infrared (IR) and visible sensors are commonly used in the target tracking and recognition system. Image fusion for these two modal images can effectively improve the system's tracking and detection accuracy. The model of dynamic contour is combined with image fusion and feature points in feature search are used toInfrared (IR) and visible sensors are commonly used in the target tracking and recognition system. Image fusion for these two modal images can effectively improve the system's tracking and detection accuracy. The model of dynamic contour is combined with image fusion and feature points in feature search are used to implement image registration accurately. Meanwhile a new feature-level image fusion is applied. Control points of B-spline curves for the target's contour in two modal images are used to implement a real-time differential coupling. This coupling makes improvement on the differential coupling proposed by Curwen, where a rigid template is transformed into a real-time transformation template with image registration. Moreover, a new dynamic equation is derved for dynamic contour after this image fusion. In this fusion, the dynamic contour's convergent shape in visible image is restricted by the target's contour in IR image. This fusion improves dynamic contour's tracking accuracy effectively. A contrasting experiment on moving hand image sequence indicates average tracking error of dynamic contour has decreased by 60.25% in visible image with this image fusion..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 760 (2005)
Improved Fast Fourier Transform Profilometry Based on Composite Grating
[in Chinese], [in Chinese], and [in Chinese]
In Fourier transform profilometry (FTP), zero frequency of the captured patterns influences the measuring range and measuring precision, and even makes the reconstruction of three-dimensional surface incorrect. π phase shifting technique is usually used to eliminate the zero component. But this method needs capturing tIn Fourier transform profilometry (FTP), zero frequency of the captured patterns influences the measuring range and measuring precision, and even makes the reconstruction of three-dimensional surface incorrect. π phase shifting technique is usually used to eliminate the zero component. But this method needs capturing two fringe patterns with π phase difference, which influences the real-time application of the method. Now a novel method is proposed, in which a composite pattern is projected. The composite pattern is formed by modulating two separate fringe patterns with π phase difference along the orthogonal direction of the two distinct carrier frequencies. The method can eliminate zero frequency by using only one fringe pattern. The experiments show that there is no distinct decrease in the precision of the novel method compared with the traditional π phase shifting technique. So, the novel method can allow for real-time and high-speed implementation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 767 (2005)
Imaging Systems
Limited-View Scanning Photoacoustic Imaging Based on Algebraic Reconstruction Techniques
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Since the reconstruction with the filtered backprojection (FBP) algorithm needs sufficient views to all points in the “detection region”, it requires a quite long time to get enough data, which restricts the application in the medical field. The limited-view photoacoustic imaging based on algebraic reconstruction technSince the reconstruction with the filtered backprojection (FBP) algorithm needs sufficient views to all points in the “detection region”, it requires a quite long time to get enough data, which restricts the application in the medical field. The limited-view photoacoustic imaging based on algebraic reconstruction techniques (ART) was studied. A Q-switched Nd∶YAG laser operating at 1064 nm was used as light source. The laser had a pulse width of 6 ns and a repetition frequency of 20 Hz. A needle polyning lidene difluoride (PVDF) hydrophone with diameter of 1 mm was used to detect photoacoustic signals. The simulations and experiments demonstrated that ART works well for limited-view data in photoacoustic imaging, and ART can improve the resolution and contrast of reconstruction images compared with the FBP. Limited-view photoacoustic imaging based on ART has far-reaching significance to noninvasive medical inspectable technology..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 772 (2005)
A New Approach for Improvemnet of CCD Imaging Resolution
[in Chinese], [in Chinese], and [in Chinese]
Improvemnet of imaging resolution is a hot topic, it plays the important role in modern war. The relation of pixel gray-level of low resolution images and high resolution image is found based on charge coupled device (CCD) imaging theory, and a new approach for improvement of CCD imaging resolution is proposed. A high Improvemnet of imaging resolution is a hot topic, it plays the important role in modern war. The relation of pixel gray-level of low resolution images and high resolution image is found based on charge coupled device (CCD) imaging theory, and a new approach for improvement of CCD imaging resolution is proposed. A high resolution image is obtained by moving multi-shift images with low resolution, the objective of improvement of CCD resolution for many times is attained. Making the indeterminate equation into unique-value equation is the essence of this approach.The simulation examples show that the approach for improvemnet of CCD imaging resolution is right, resolution can be improved 2 times, 3 times and even N times in theory. In addition, operation time is lower than other methods..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 777 (2005)
Instrumentation, Measurement and Metrology
Fringe Analysis with Hilbert Transform and Its Application in the Measurement of Aspheric Mirror
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A method for interferometric phase's demodulation with a discrete Hilbert transform is proposed. A Hilbert transform demodulated phase principle is represented and the phase information of aspheric surface is evaluated only one interferogram. The sine and cosine components are calculated from a single interference A method for interferometric phase's demodulation with a discrete Hilbert transform is proposed. A Hilbert transform demodulated phase principle is represented and the phase information of aspheric surface is evaluated only one interferogram. The sine and cosine components are calculated from a single interference signal. Then wavefront reconstruction is achieved using Zernike polynomical fitting. In addition, the phase-extraction algorithm, error correction and some applications to the measurement of the surface shape are discussed. On-line measurements to aspheric surface are realized. Several experiments showed the accuracy of the measurement to be λ/10 ( RMS)..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 781 (2005)
Rapid Measurement Method of Absolute Radiometer by Using Forecast Radiation in Electrically Heating Compensation
[in Chinese], [in Chinese], and [in Chinese]
Two phases of radiation reception and electrical calibration are needed for absolute radiometer to measure radiation. Because absolute radiometer is thermoelectricity detector, at the two phase temperature response of the cavity could be compared after the receive cavity of the absolute radiometer reaches balance, and Two phases of radiation reception and electrical calibration are needed for absolute radiometer to measure radiation. Because absolute radiometer is thermoelectricity detector, at the two phase temperature response of the cavity could be compared after the receive cavity of the absolute radiometer reaches balance, and then the radiation value is electrically calibrated. According to the law that the temperature of the reception cavity rises up exponentially when radiated or heated up, dynamic forecast of the temperature is adopted and then it gets compensation by heating up with electricity. A new method of measurement is worked out under the state that the temperature of the cavity maintains invariable both at the phases of observation and calibration. The rapid measurement method was used on two Solar Irradiance Absolute Radiometers (SIARs) named SIAR-2a and SIAR-2b constructed for Physikalisch-Meteorologisches Observatorium Davos/World Radiometric Center (PMOD/WRC). Comparison experiments were carried at WRC for a year and a half. The sun was observed together with the instruments of WSG more than 10000 times at the same time. The data obtained from PMOD/WRC shows that its absolute precision reaches 0.08%. The precision of the new method is same with the old one (the balance is slower and the measurement time is longer) but the measurement cycle is shorter..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 786 (2005)
Study on Fast Ultra-Precision Measurement Model in Laser Heterodyne Interferometry
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In order to describe accurately laser heterodyne interferometer measurement in fast ultra-precision, a new model is proposed. The laser heterodyne interferometer measurement theory is analyzed, and laser interferometer fast ultra-precision model based on the Doppler frequency shift model is deduced. In the model, the iIn order to describe accurately laser heterodyne interferometer measurement in fast ultra-precision, a new model is proposed. The laser heterodyne interferometer measurement theory is analyzed, and laser interferometer fast ultra-precision model based on the Doppler frequency shift model is deduced. In the model, the integral of v2/c is added, the part is ignored in laser heterodyne interferometer conventional model. With this model, when the highest measurement speed is up to 1 m/s and the displacement is up to 3 m, about 18 nm of measurement error is reduced, and the residual error is removed, the fast ultra-precision measurement is realized..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 791 (2005)
Study on Laser Doppler Demodulation System Applied to Remote Measurement in High Altitude
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
To measure artificial seismic wave with high accuracy in remote distance, the theory and methods of coherence of light resource, stability of system, intensity and signal to noise ratio (SNR) of laser Doppler signal, and sensitivity and accuracy of displacement measurement are investigated. Two optical stops (whose diaTo measure artificial seismic wave with high accuracy in remote distance, the theory and methods of coherence of light resource, stability of system, intensity and signal to noise ratio (SNR) of laser Doppler signal, and sensitivity and accuracy of displacement measurement are investigated. Two optical stops (whose diameter is 1.8 mm) inserted into the resonant cavity and collimating structure of light output (4×) are adopted to increase coherent length and measurable distance. Acousto-optical modulation device and 1/4 wave plate are inserted respectively into two light paths to implement the matching of polarization, to make the system more stable and the SNR higher. The lens focusing is adopted to increase signal intensity. Trent reverse reflection device is adopted to offset the effect caused by beat and cross sliding during displacement or vibration and to enhance measurement sensitivity and accuracy nearly one time. Through the principle experiment of vibration in 2 m distance by using above system, the measurement relative error of amplitudeis of 0.1% and the measurable frequency up to 750 Hz are obtained. So the system can be applied to remote measurement of artificial seismic wave in high altitude..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 795 (2005)
A New Method to Calibrate Accurately a Photoelastic Modulator
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A new method to calibrate accurately a photoelastic modulator is proposed to compensate for the shortcomings of current calibration methods. Firstly, the photoelastic modulator is calibrated roughly to locate its peak retardation around 1.841 rad using the fundamental component's maximum of the detection signal in A new method to calibrate accurately a photoelastic modulator is proposed to compensate for the shortcomings of current calibration methods. Firstly, the photoelastic modulator is calibrated roughly to locate its peak retardation around 1.841 rad using the fundamental component's maximum of the detection signal in an optical system for calibration which is composed of polarizer, waveplate, photoelastic modulator and analyzer. Then the waveplate is taken away to form an optical system for accurate calibration. Before and after the analyzer is rotated, the direct current and secondary harmonic components of the detection signals are obtained to calculate the peak retardation of the photoelastic modulator. The accurate calibration for the photoelastic modulator is realized and its precision is independent of the incident intensity and the circuit parameters. The calibration method was verified by experiments. The calibrated error of the method is less than 0.7%. The peak retardation of the photoelastic modulator is small in the calibration, so the photoelastic modulator can be calibrated in the long-wave band of its spectral range using this calibration method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 799 (2005)
Optical Measurement Platform for Micro-Structures Characterization
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Micro-structures are a few typical elements of micro-electromechanical system (MEMS). The physical dimensions, motion characteristics, material and mechanical properties have important influences on the system performance of MEMS device. An optical measurement platform for static and dynamic characteristics of micro-stMicro-structures are a few typical elements of micro-electromechanical system (MEMS). The physical dimensions, motion characteristics, material and mechanical properties have important influences on the system performance of MEMS device. An optical measurement platform for static and dynamic characteristics of micro-structures is put forward. Computer micro-vision, Mirau microscopic interferometry, stroboscopic photography and laser Doppler vibrator are integrated into this platform. In-plane and out-of-plane periodic motion characteristics of micro-resonator are measured, and out-of-plane transient motion of micro-mirror is analyzed. In-plane displacement, motion phase and resonance frequency can be measured by integrating computer micro-vision with stroboscopic photography, and the repeatable accuracy of in-plane displacement is 30 nm. Out-of-plane displacement and tolerance can be measured by integrating Mirau microscopic interferometry with stroboscopic photography, and the repeatable accuracy of out-of-plane displacement is 3 nm. Laser Doppler vibrator has an advantage of analyzing the motion in frequency domain, and it is the complementarity of measuring periodic motion in time domain..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 803 (2005)
Support Schemes and Thermal Deformation Analysis of Large-Aperture Interferometer Mirrors
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In the field of inter-satellite communication, the measurement of large-aperture and diffraction limit wavefront is required. In order to ensure the measuring precision, the deformations of the interferometer mirrors induced by self-weight and the thermal effects must be controlled strictly. In a variety of support schIn the field of inter-satellite communication, the measurement of large-aperture and diffraction limit wavefront is required. In order to ensure the measuring precision, the deformations of the interferometer mirrors induced by self-weight and the thermal effects must be controlled strictly. In a variety of support schemes, the surface deformations of large-aperture interferometer mirrors are computed by means of finite element method. By comparison, the band support of 180° wrap angle is accepted to be optimum. In that case, the peak-to-valley (P-V) value is only 1.35 nm and RMS value is 0.363 nm. According to the results, the statically indeterminate supporting structure is designed. In that mounting configuration, the thermoelastic analysis for the mirror is performed for special thermal effects (axial, radial, circumferential temperature gradients). According to the results, it is clear that the influence of thermal gradient effects is much greater than the ones of self-weight. Lastly, some suggestions (relative constant temperature circumstance and average processing) are given to reduce the influence of thermal effects..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 809 (2005)
Integrated Optics
Beam Expansion Law and Its Application in Total Internal Reflection Induced by Thermo-Optic Effect
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Based on the thermal model of thermo-optic device and analytical expression of temperature distribution, by employing the ray optics, the beam expansion cause and law in thermo-optic-effect-induced total internal reflection (TIR) are analyzed by calculating the ray reflection trace in different meridan plane of the corBased on the thermal model of thermo-optic device and analytical expression of temperature distribution, by employing the ray optics, the beam expansion cause and law in thermo-optic-effect-induced total internal reflection (TIR) are analyzed by calculating the ray reflection trace in different meridan plane of the core, and a theoretical method to calculate the specific expanding value of beamwidth is given. A 2×2 polymer thermo-optic switch with high reflection coefficient is designed as an illustration of the law. Utilizing the law in authors′ design, the structure parameters of expansion waveguide width, buried depth of the core, and enlarged reflection area width are calculated. Simulation results show that the structure exhibits a reflection coefficient of 82.6 % at reflecting state, a cross coefficient of 84.4% at cross state, the cross talks are better than 30 dB. The simulation optimized result of these structure parameters agrees with theoretical calculation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 816 (2005)
Lasers and Laser Optics
Study on Stable Multi-Wavelength Erbium-Doped Fiber Laser at Room Temperature
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A sinusoidal phase modulator composed of a piece of single-mode fiber around a piezoelectric transducer is inserted in the linear resonant cavity, which makes the loss corresponding to different lasing lines uncertain, the mode competition owing to the homogeneous broaden line in erbium-doped fiber is suppressed and thA sinusoidal phase modulator composed of a piece of single-mode fiber around a piezoelectric transducer is inserted in the linear resonant cavity, which makes the loss corresponding to different lasing lines uncertain, the mode competition owing to the homogeneous broaden line in erbium-doped fiber is suppressed and the unstable single-wavelength lasing at room temperature is eliminated. In order to achieve flat multi-wavelength output, a long-period fiber grating with loss peak at 1530 nm is used to obtain flat gain spectrum. The stable output from the multi-wavelength erbium-doped fiber laser is realized. Simultaneous multi-wavelength lasing is observed with 0.45 nm intervals defined by the reflective comb-like filter. In the meantime, there are 9 lasing lines in power differences less than 10 dB and the side-mode suppression ratio is higher than 25 dB..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 821 (2005)
Application of Optical Matrix in Semiconductor Laser Coupling
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The optical matrix under paraxial approximation can make the calculation of optical transmission easy and convenient in designing optical system. The ABCD transformation matrix method for the coupling optical system design is introduced, using the ABCD law of the Gaussian beam. The design of a coupling system of semicoThe optical matrix under paraxial approximation can make the calculation of optical transmission easy and convenient in designing optical system. The ABCD transformation matrix method for the coupling optical system design is introduced, using the ABCD law of the Gaussian beam. The design of a coupling system of semiconductor laser diode to single-mode fiber is given in detail; additionally, the changes of the coupling loss with the coupling distance of the system are calculated, and then the recently reported results are compared, they roughly agree with each other, which shows the method is feasible. From the whole design and the calculation for coupling efficiency, the ABCD matrix makes the design easier and reduces the cumbersome calculation. Compared with general diffraction calculation, it is a convenient and effective method and it can give some instructional suggestion for fabricating the semiconductor laser diode coupler..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 825 (2005)
Cooling of a Side-Pumped Laser Slab by Heat Sink
[in Chinese], [in Chinese], and [in Chinese]
The thermal stress of the high-power solid-state laser slab is becoming a more and more serious problem hindering the further increase of the power of the laser, the laser slab can operate safely only if it is efficiently cooled. Based on the non-uniform heat transfer coefficient model, researches are performed on the The thermal stress of the high-power solid-state laser slab is becoming a more and more serious problem hindering the further increase of the power of the laser, the laser slab can operate safely only if it is efficiently cooled. Based on the non-uniform heat transfer coefficient model, researches are performed on the cooling characteristics of the both side-pumped laser slab with non-uniform heat source by forced convection cooling in a narrow passage. Numerical simulations are conducted to investigate the temperature and thermal stress distributions of the laser slab cooled by forced convection cooling through heat sink. Three kinds of materials are selected to serve as the heat sink, they are the composite slab, sapphire, and diamond, respectively. The calculation results show that neglecting the non-uniformity of the convective heat transfer coefficient causes an underprediction of the temperature and thermal stress of the slab. For the present side-pumped/side-cooled laser slab case, the cooling scheme using the diamond heat sink is the best, that using the sappire heat sink follows, whereas that using the composite slab heat sink does not apply..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 829 (2005)
Medical Optics and Biotechnology
Application of the Quasi-Weibull Distribution Density Function to Data Analysis of Fluorescence Lifetime Imaging
[in Chinese], and [in Chinese]
Fluorescence lifetime imaging is a rather effective and powerful method that can be used to analyze complex biological tissues and molecules. Conventional analyses of fluorescence lifetime data resolve the fluorescence decay profile in terms of discrete single exponential components with distinct lifetimes. In complex,Fluorescence lifetime imaging is a rather effective and powerful method that can be used to analyze complex biological tissues and molecules. Conventional analyses of fluorescence lifetime data resolve the fluorescence decay profile in terms of discrete single exponential components with distinct lifetimes. In complex, heterogeneous biological samples such as tissue, multi-exponential decay functions can appear to provide a better fit to fluorescence decay data than the assumption of a single-exponential decay, but the assumption of multiple discrete components is essentially arbitrary. Quasi-Weibull distribution density function was likely to provide a truer representation of the underlying fluorescence dynamics. As comparing with those of single exponential and multi-exponential decay functions, the novel model can yield the better goodness of fit using data from multi-well plate assays of chemically and biologically interesting fluorophores. At the same time, the potential application of the quasi-Weibull distribution density function to fluorescence lifetime imaging was discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 835 (2005)
Up-Converting Phosphor Technology-Based Biosensor and Its Application
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An up-converting phosphor technology-based biosensor (UPT-based biosensor) was developed for immunoassay and fast detecting using up-converting phosphor (UCP) as the biological marker. UCP can emit visible light when excited by infrared light. Through detecting and analyzing the content of UCP particle on the test striAn up-converting phosphor technology-based biosensor (UPT-based biosensor) was developed for immunoassay and fast detecting using up-converting phosphor (UCP) as the biological marker. UCP can emit visible light when excited by infrared light. Through detecting and analyzing the content of UCP particle on the test strip after immunoreaction, the UPT-based biosensor can obtain the concentration information of target analyte in the sample. The UPT system realized the quantitative detection and had good ability to meet the need of some emergencies. High sensitivity (nanogram/ml), good linear relationship in the concentration range of 200～6000 ng/ml and an excellent correlation (R2≥0.95) were verified by quantitative detection results. The sensitivity of the UPT-based biosensor was better than that of the indirect hemagglutination test in the practical application. All the results were comparable with that obtained by Western Blot detection. The UPT-based biosensor had stable, reliable and sensitive working performances, and it can meet the need of some various applications such as rapid immunoassay, chemical and biological detection and so on..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 841 (2005)
Nonlinear Optics
Propagation Properties the Paraxial Gaussian Beam in Strongly Nonlocal Media
[in Chinese], [in Chinese], and [in Chinese]
The propagation of paraxial Gaussian beam in three-dimensional strongly nonlocal media is disccussed with a variational approach. A set of evolution equations are obtained for the beam. The potential function, critical power and ε determined by both the material property and the initial beam width are obtained. The anaThe propagation of paraxial Gaussian beam in three-dimensional strongly nonlocal media is disccussed with a variational approach. A set of evolution equations are obtained for the beam. The potential function, critical power and ε determined by both the material property and the initial beam width are obtained. The analysis of the potential function shows that the model for the beam propagation in the strongly nonlocal media is valid only when 0≤ε<1/3. A stable optical spatial soliton is found when the input power equals the critical power. Generally, the beam width takes periodical contraction, diffraction, or always diffracts respectively. The results agree with the numerical solutions..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 848 (2005)
Optical Devices
A LED Light Unit for the Projector
[in Chinese], [in Chinese], and [in Chinese]
For current light source of projectorUHP lamp, the disadvantages of short lifetime, high colour temperature, having harmful light, high heat density etc., restrict the application of projector in home entertainment. Recent development of LED provides the possibility of LED being a substitute light source of UHP lamp. AFor current light source of projectorUHP lamp, the disadvantages of short lifetime, high colour temperature, having harmful light, high heat density etc., restrict the application of projector in home entertainment. Recent development of LED provides the possibility of LED being a substitute light source of UHP lamp. A LED-based lighting unit composed of a LED, a collimating lens, a front fly-lens and a back fly-lens is brought forward. Several such lighting units make a basic lighting system of projector. The divergence angle of light beam from LED is compressed by collimator lens. Then the light beam is divided into several tiny light beams by the front fly-lens, and each tiny light beam will be converged to micro-display panel by converging lens. So, the light energy is gathered and the light field is redistributed. The requirements of projector on light flux and homogeneity could be met. The back fly-lens is used to match with following optical elements. As an application of the lighting unit, a signal panel liquid crystal on silicon projector is analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 855 (2005)
Quantum Optics
The Matrix Method in Treating Atom Interferometer
[in Chinese], and [in Chinese]
Based on the Schrdinger equation for atomic waves, the relation between the gravity and the phase difference of atom interferometer is derived. A new 3×3 matrix method was introduced to calculate the phase difference for complicated system of the multiloop interferometers, which simplifies the calculation greatlyBased on the Schrdinger equation for atomic waves, the relation between the gravity and the phase difference of atom interferometer is derived. A new 3×3 matrix method was introduced to calculate the phase difference for complicated system of the multiloop interferometers, which simplifies the calculation greatly. By use of this method, not only the propagation matrix of atom beam in free space under the influence of gravity can be, but also the interaction matrix of atom beam with π/2 and π pulse can be obtained. As an example, the phase difference for the three-pulse atom gravimeter by using the 3×3 matrix is derived, and the results obtained coincide precisely with those obtained by Wolf et al. through the integration of the Lagrangian over the classical trajectory. Finally, the phase difference of five-pulse atom gravimeter is analyzed to illustrate the convenience of the 3×3 matrix method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 6, 860 (2005)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20