Contents
2007
Volume: 27 Issue 4
34 Article(s)
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Atmospheric Optics and Oceanic Optics
The Characteristic of the Cracked Beam Spot
[in Chinese], and [in Chinese]
The beam spot will break up into some cracks when the beam propagates through the turbulent atmosphere. The characteristic of the cracked beam spot are studied statistically for different emitting beam shapes and beam qualities, and with different turbulent effects. It is shown that, with the degeneration of the beam sThe beam spot will break up into some cracks when the beam propagates through the turbulent atmosphere. The characteristic of the cracked beam spot are studied statistically for different emitting beam shapes and beam qualities, and with different turbulent effects. It is shown that, with the degeneration of the beam spot and the turbulence being stronger, the total radius of the beam spot and the number of the fragments will increase; meanwhile the radius of the fragments will keep invariable almost: about the radius of the bucket which contain 63% of the total energy. In order to understand this phenomenon, four different kind of situations: the diffraction of thin ring, diffraction of double apertures, decomposing the field into the superimposition of different frequencies and the propagation of solid beam with strong turbulent effects, are analyzed and primary explanation are given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 567 (2007)
Fiber Optics and Optical Communications
Improvement of Extinction Ratio of 40 GHz Optical Clock Using with High-Birefringence Fiber Loop Mirror
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The quality of clock signal plays a key role in synchronization, demultiplexing and optical decision. The extinction ratio of optical clock signal can be greatly increased after passing through birefringent fiber loop mirror (FLM), due to its flexibly tunable filtering characteristics, and then the clock signal qualityThe quality of clock signal plays a key role in synchronization, demultiplexing and optical decision. The extinction ratio of optical clock signal can be greatly increased after passing through birefringent fiber loop mirror (FLM), due to its flexibly tunable filtering characteristics, and then the clock signal quality is improved. We propose a method of using high-birefringence fiber loop mirror to enhance the extinction ratio (ER), numerically simulate the transmission spectrum variation of birefringent fiber loop mirror by adjusting birefringence device' polarization delay, fast/slow axis angle and optical path difference of the polarization controller; and theoretically analyze the clock spectrum after it passes through birefringent fiber loop mirror with an unperfect extinction ratio. With a 40 GHz clock signal extracted by Fabry-Pérot filter as input, an experiment is performed. The result shows that the extinction ratio of the input clock is improved by 13 dB, which verifies the results of numerical simulation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 574 (2007)
Design and Fabrication of 10 Gb/s Transponder with Electronic Dispersion Compensation
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
10 Gb/s transponder with electronic dispersion compensation (EDC) is designed and fabricated. Inter-symbol-interference brought about by chromatic dispersion and polarization mode dispersion is minimized by electronic dispersion compensation. So the transmission distance is greatly enhanced .Apart from electronic dispe10 Gb/s transponder with electronic dispersion compensation (EDC) is designed and fabricated. Inter-symbol-interference brought about by chromatic dispersion and polarization mode dispersion is minimized by electronic dispersion compensation. So the transmission distance is greatly enhanced .Apart from electronic dispersion compensation, the transponder fabricated features DFB+EA integrated light source and avalanche photodiode (APD) module carrying transimpedance amplifier. Experiments and tests show that the sensitivity of back-to-back transmission is -24.6 dBm, and the transmission distance of the module is more than 100 km, the sensitivity is -20.8 dBm after transmission of 100 km G.652 fiber. Compared with transponder without electronic dispersion compensation, which has a transmission distance of about 50 km, the transmission distance is doubled. Hence the requirement of dispersion management of the system is cut down greatly and cost reduced..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 579 (2007)
Bistability Phenomenon in Erbium-Doped Fiber
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Optical bistability is observed in a fiber ring laser with erbium-doped fiber (EDF) as the gain medium. A qualitative explanation about the mechanism of optical bistability is put forward, i.e. the long erbium-doped fiber can be divided into two different parts, where gain saturation and absorption saturation prevails Optical bistability is observed in a fiber ring laser with erbium-doped fiber (EDF) as the gain medium. A qualitative explanation about the mechanism of optical bistability is put forward, i.e. the long erbium-doped fiber can be divided into two different parts, where gain saturation and absorption saturation prevails respectively and the absorption saturation has a lower saturation threshold. Furthermore, the gain characteristic of EDF is measured and fitted with a formula derived from the qualitative explanation. At last, a quantitative explanation of the optical bistability is put forward with the gain characteristic of the erbium-doped fiber..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 583 (2007)
Optimization of Chirped Fiber Bragg Gratings by Asymmetrically Apodization Method
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Asymmetrical apodization method is introduced to optimize chirped fiber Bragg gratings based on the analysis of its reflectivity spectrum and time delay response. The optimization effects for grating parameters, by the optimum apodization ratio of the symmetrical apodization, the left-shifted and right-shifted asymmetrAsymmetrical apodization method is introduced to optimize chirped fiber Bragg gratings based on the analysis of its reflectivity spectrum and time delay response. The optimization effects for grating parameters, by the optimum apodization ratio of the symmetrical apodization, the left-shifted and right-shifted asymmetrical apodization methods and different apodization functions, are analyzed and compared. The results show that, compared with symmetrical apodization method, the asymmetrical apodization method can avoid the disadvantage of the former method that widens the reflectivity bandwidth by reduction of apodization ratio, which meanwhile increases the time delay ripple. The left-shifted apodization method can reduced the time delay ripple by 43.5%, adjacent with the experimental result of 39.9%, while the refectivity spectrum is nearly unchanged. Furthermore, better performance can be obtained with super-Gaussian function on left-side and Hamming function on right-side of chirped fiber Bragg gratings than Hamming function on both sides. The plain part of the reflectivity ripple is reduced 89.3%, as well as fitting error of group delay ripple 16.7%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 587 (2007)
Photonic Crystal Fiber with Single Polarization
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel photonic crystal fiber that maintains single polarization at a relatively wide wavelength range is presented and analyzed with a full-vectorial compact-two-dimensional finite-difference method. When the space of hole to hole is 2.3 μm, the diameter of the larger holes in the first ring is 2.4 μm, the diameter oA novel photonic crystal fiber that maintains single polarization at a relatively wide wavelength range is presented and analyzed with a full-vectorial compact-two-dimensional finite-difference method. When the space of hole to hole is 2.3 μm, the diameter of the larger holes in the first ring is 2.4 μm, the diameter of the smaller air holes in the first ring is 1.4 μm, and the diameter of other air holes is 0.6 μm, this single polarization fiber (SPF) maintains a high mode birefringence at wavelength range of 1.02～2.0 μm. When the diameter of the larger air holes is 2.8 μm, and the diameter of the smaller air holes is 1.4 μm, only one polarization mode can be guided in the range of 1.35～2.0 μm and the modal birefringence at the wavelength 1.31 μm can reach 3.5×10-3..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 593 (2007)
Fourier Optics and Signal Processing
Spectral Analyses of Rare-Earth Ions in Solid Luminescent Materials
[in Chinese], [in Chinese], and [in Chinese]
Spectral analyses are the basis of estimating spectroscopic properties of rare-earth ions doped materials and Judd-Ofelt (J-O) theory is considered the foundation of spectral analyses. The process calculating three intensity parameters according to J-O model and some important radiative parameters are detailed; the reaSpectral analyses are the basis of estimating spectroscopic properties of rare-earth ions doped materials and Judd-Ofelt (J-O) theory is considered the foundation of spectral analyses. The process calculating three intensity parameters according to J-O model and some important radiative parameters are detailed; the reasonable applications of related formulas are discussed; the originations of errors in calculations are summarized, and a different approach is recommended to obtain more reliable radiative parameters. Experimental oscillator strengths are suggested to be calculated by transmission spectra. The light reflection, scattering and the inherent absorption of matrix should be subtracted in absorption coefficient and cross-section calculations. The line shape factor must be taken into account for determining the average wavenumber and wavelength. The line shape of measured emission spectrum is proposed to be considered for calculating emission cross-sections at different wavelength. However, the errors are usually relatively high, even leading to unreliable results, because many approximations and assumptions were involved in J-O model. It is put forward that if measured radiative lifetimes and branching ratios at low temperature are used to calculate parameters, obtained results will be more reliable and meaningful..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 598 (2007)
A Method of Phase-Shifting Measurement by the Difference of Phase-Shifting Interferograms
[in Chinese], [in Chinese], and [in Chinese]
A method of phase-shifting measurement of interferograms is proposed by the difference between two interferograms. In this method a phase-shifting interferogram is subtracted from the other one,and then the phase-shifting difference function, in which the amplitude is correlated only with the phase-shifting value, is oA method of phase-shifting measurement of interferograms is proposed by the difference between two interferograms. In this method a phase-shifting interferogram is subtracted from the other one,and then the phase-shifting difference function, in which the amplitude is correlated only with the phase-shifting value, is obtained and normalized, so the phase-shifting value can be calculated by the maximum extremum of phase-shifting difference function, meanwhile two metheds including the direct search method and the average method are introduced to determine the maximum extremum of the normalized function. Experimental and analysis results show the phase-shifting value between two interferograms can be obtained when contrast function of interferogram is determined and the results are not affected by the measured phase. And as a statistical analysis for many sampling points in spatial domain is used in calculation, the high-precision phase-shifting measurement can be achieved. For another, as Fourier transform is not used in above proposed method, and it can be used in analyzing the high spatial frequency fringes, sparse parallel fringes,even arbitrary form fringes. Meanwhile the measuring precision of the proposed method is compared with that of Fourier transform method, and it is proved the measuring precision of two methods is identical..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 603 (2007)
Two Methods in Checking Light Beam Collimation with Double Spiral Moiré Fringes
[in Chinese], and [in Chinese]
The basic principle to check light beam collimation with double spiral moiré fringes is illustrated, and the relationship of the characteristic parameters of double spiral moiré fringes and the angle of divergence, i.e. collimation accuracy, is further deduced and analyzed. In the double spiral moiré friThe basic principle to check light beam collimation with double spiral moiré fringes is illustrated, and the relationship of the characteristic parameters of double spiral moiré fringes and the angle of divergence, i.e. collimation accuracy, is further deduced and analyzed. In the double spiral moiré fringes analysis, the pure moiré fringes are extracted by low-pass filter in the frequency domain at first, and then the characteristic parameter of the pure moiré fringes is extracted. Two methods are introduced to extract the characteristic parameter, one is Fourier transform algorithm, in which the phase information is derived by Fourier transform in turn, and another is spatial phase shift arithmetic, enlightened by the traditional temporal phase algorithm. The problems of re-sampling in polar coordinates and relevant formulae in the two methods are also discussed, and the results of computer simulation are presented. The result shows that the essence of the above two methods is acquisition of the average of the whole moiré fringes trend, and at last the angle of divergence is obtained with a high accuracy. The error of the fringes period of selfimaging is within ±2.8‰..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 609 (2007)
Holography
Spatial Resolution of Polyvinyl Alcohol/Acrylamide Based Photopolymer Holographic Recording Material
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Polyvinyl alcohol/acrylamide based photopolymer system has a relatively low spatial resolution, which limits its wide applications in the fields such as reflection display holography, high-density holographic data storage, etc. A new strategy of employing low molecular-weight polyvinyl alcohol as binder to improve the Polyvinyl alcohol/acrylamide based photopolymer system has a relatively low spatial resolution, which limits its wide applications in the fields such as reflection display holography, high-density holographic data storage, etc. A new strategy of employing low molecular-weight polyvinyl alcohol as binder to improve the spatial resolution of such photosensitive system is proposed. The comparative experiments of different photosensitive system with various molecular weights (72000,15000,9000) are conducted to study their effects on the diffraction efficiency and spatial resolution. The experimental results show that the photosensitive system with low molecular weight of 9000 has much higher resolution and diffraction efficiency, and bright volume transmission grating with spatial frequency of 3000 line/mm and diffraction efficiency higher than 85% can be recorded successfully on the optimum photopolymer material at the exposure level of 40 mJ/cm2. Finally, the preliminary applications of angular multiplexing holographic storage are successfully demonstrated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 616 (2007)
Forgery Prevention Based on In-Line Fourier Holographic Watermark with Double Random Phase Encryption
[in Chinese], and [in Chinese]
A method to fabricate encrypted Fourier transform holographs is provided. With optical system or computer, the original digital image is modulated by double random phase plates and interferes with the reference light, and then the encrypted Fourier transform holograph is created, which can be regarded as the watermark A method to fabricate encrypted Fourier transform holographs is provided. With optical system or computer, the original digital image is modulated by double random phase plates and interferes with the reference light, and then the encrypted Fourier transform holograph is created, which can be regarded as the watermark and hidden in a host image to guarantee the copyright authentication. The printing and scanning experiments prove that the digital images with watermark can be printed on the certificates with ordinary printing technology. The digital images with watermark can be scanned and input into the computer, and the digital watermark can be extracted with blind detection technology. The credibility of the printed matter is proved, and the anti-fake performance is improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 621 (2007)
Image Processing
Adaptive Window Filter for Electric Speckle Pattern Interferometry Fringe Pattern
[in Chinese], [in Chinese], and [in Chinese]
Electric speckle pattern interferometry (ESPI) is a modern measuring technology and has many applications. But the high speckle noise makes the signal-to-noise ratio (SNR) of the electric speckle pattern interferometry fringe pattern very low and so limits the applications of electric speckle pattern interferometry. ItElectric speckle pattern interferometry (ESPI) is a modern measuring technology and has many applications. But the high speckle noise makes the signal-to-noise ratio (SNR) of the electric speckle pattern interferometry fringe pattern very low and so limits the applications of electric speckle pattern interferometry. It is hard for usual filters to filter off the high speckle noise. A novel filtering method is proposed based on contoured window filter. Because the contoured window is obtained from fringe orientations, so we proposed a new algorithm to get more precise orientations. This algorithm can calculate the precise orientations and estimate the fringe widths at the same time. Based on this algorithm, adaptive window filter is designed. This new filter can adapt its shape following the fringe orientations and adapt its size according to the density of the local fringe. Last the phase can be obtained from the filtered image whose density varies a lot..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 625 (2007)
Assessment Method of Modulation Transfer Function of On-Orbit Space Optical Remote Sensor Using Neural Network
[in Chinese], [in Chinese], and [in Chinese]
Through analyzing the model of modulation transfer function (MTF) of on-orbit space optical remote sensor (SORS) and remote images, the eigenvectors related to MTF in the images are found out, using neural network (NN), complete assessing the MTF of space optical remote sensor through images of any landscape. First, reThrough analyzing the model of modulation transfer function (MTF) of on-orbit space optical remote sensor (SORS) and remote images, the eigenvectors related to MTF in the images are found out, using neural network (NN), complete assessing the MTF of space optical remote sensor through images of any landscape. First, remote images with different MTF levels were simulated, and they were used as the training base of NN, then the eigenvectors related to MTF directly and that related to landscape structure were abstracted respectively, and they were used as the inputs of NN, after being trained by a great lot of simulated images in the training base that MTF are known, the ANN could assess the MTF of totally unknown images. This method could assess the MTF of SORS through images of any landscape, and needn’t the special views on the ground or aerial images as reference. The experiment results show that when noise is not considered, the mean assessment error is approximately 6%, or else, the mean error is approximately 9%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 631 (2007)
Target Detection for Remote Sensing Image Based on Gaussian Transformation of Background
[in Chinese], [in Chinese], and [in Chinese]
A new target detection algorithm is presented which deals with the problem of detecting target in remote sensing image. Based on the assumption that the distribution of the homogenous land surface is a Markov random field, we analyzed that the distribution of the homogenous land surface background is Gaussian. This modA new target detection algorithm is presented which deals with the problem of detecting target in remote sensing image. Based on the assumption that the distribution of the homogenous land surface is a Markov random field, we analyzed that the distribution of the homogenous land surface background is Gaussian. This model leads to an efficient and effective detector for discriminating man-made objects in real remote sensing imagery. First, the original image is transformed into Gaussian space as the ideal background. And then, the residual image is obtained by subtracting the ideal background from the original images. Finally, a conventional detector is applied to the residual image to complement the further target detection. Because the targets have values deviating significantly from the distribution of the background, the background can be severely decreased during the subtraction. Therefore, the new algorithm has better performance. Some experiments of real remote sensing images proved the validity of the new algorithm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 638 (2007)
Imaging Systems
Novel Polarization Interference Imaging Spectrometer with Adjustable Lateral Displacement Savart Polariscope
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
To avoid the problems of the classical interference imaging spectrometer, such as poor stabilization, and intractable interference fringes, a novel polarization interference imaging spectrometer based on a new adjustable lateral displacement Savart polariscope is developed. The effect of the incident angle on the opticTo avoid the problems of the classical interference imaging spectrometer, such as poor stabilization, and intractable interference fringes, a novel polarization interference imaging spectrometer based on a new adjustable lateral displacement Savart polariscope is developed. The effect of the incident angle on the optical path difference, state of polarization and interference fringes of the system is deduced in detail. The work principle and operation mode of this spectrometer are also analyzed, which proves that this interference imaging spectrometer has less weight, smaller capacity, better vibrational resistance, splitted beams with parallel and uniform distribution, and clear interference pattern, and can be widely used in many different fields. The theoretical and practical guidance is thereby provided for the study, design, and debugging or engineering of the new polarization interference imaging spectrometers with adjustable lateral displacement..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 27, Issue 4, 643 (2007)
Study the Measurement Range of Wavelet Transform Profilometry
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
By the wavelet transform profilometry, the height distribution of an object can be obtained by calculating the wavelet coefficient of the deformed fringe pattern at the “ridge” position even there are some frequency overlaps between the fundamental frequency and the higher-order spectra. It provides a way to overcome tBy the wavelet transform profilometry, the height distribution of an object can be obtained by calculating the wavelet coefficient of the deformed fringe pattern at the “ridge” position even there are some frequency overlaps between the fundamental frequency and the higher-order spectra. It provides a way to overcome the shortcoming of Fourier transform profilometry. But by now the discussion of the measurement range of wavelet transform profilometry has not been done yet. The frequency-domain description of wavelet coefficient is deduced from the point of view of the frequency analysis. And the measurement range of the wavelet transform profilometry is discussed, including the structure condition of the measurement system and the sampling condition introduced by digitizing the deformed fringe. A conclusion has been made that as long as there aren't any instantaneous frequency overlapping, both within a frequency island and between the adjacent periods, the correct reconstruction can be obtained by wavelet transform profilometry. In another word, under conditions that the instantaneous height variation of the test object in the fringe pattern at any position satisfies h/xx=b<1/3 and the number m of sampling points in one period must be greater or equal to 3, the correct phase included in the deformed fringe pattern can be retrieved by this method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 647 (2007)
Instrumentation, Measurement and Metrology
Phase Compensating Detection Method of Interferometric Fiber-Optic Hydrophones Based on Tuning the Frequency of the Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel signal detection method for interferometric fiber optic hydrophones is described. It compensates the phase of the interferometer by tuning the frequency of the laser. The principle of this method is introduced in details. The demodulation error is analyzed and simulated theoretically. A system of data acquisitiA novel signal detection method for interferometric fiber optic hydrophones is described. It compensates the phase of the interferometer by tuning the frequency of the laser. The principle of this method is introduced in details. The demodulation error is analyzed and simulated theoretically. A system of data acquisition and processing is programmed, and a fiber hydrophone is tested. The average acoustic pressure sensitivity is -162.2 dB (0 dB=1 rad/μPa) over the frequency range of 20 Hz to 1.3 kHz, and the fluctuation is smaller than ±0.8 dB, which accords well with the results obtained with the method of phase generated carrier demodulation. The experimental results prove this method is feasible. This method has the advantages of no electric elements in the sensing head, the simplicity of signal processing and the wide frequency range of detection. It can be applied to all kinds of signal detection of interferometric fiber-optic sensors..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 654 (2007)
High-Speed and Real-Time Measurement of Stokes Parameters
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
To meet the need for measurement of state of polarization (SOP) altering in high speed, a new technology to realize high-speed state of polarization measurement was proposed. A general means of state of polarization measurement using polarizer and quarter wave plate (QWP) was given, and based on this technology new forTo meet the need for measurement of state of polarization (SOP) altering in high speed, a new technology to realize high-speed state of polarization measurement was proposed. A general means of state of polarization measurement using polarizer and quarter wave plate (QWP) was given, and based on this technology new formulas which can both meet the requirement of high-speed and real-time state of polarization measurement are brought out. To validate the feasibility and stability of the new theory, a particular project of experiment is made. The experimental system can perform over 700 polarization measurements per second, the results show that, measuring speed is mainly determined by the performance of the electronic parts and thus the measuring speed can be greatly accelerated by improving electronic parts of the system, the result is also proved to be credible and stable, and the method is useful..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 659 (2007)
Simultaneous Phase-Shifting Interferometry Based on Two-Dimension Grating
[in Chinese], [in Chinese], and [in Chinese]
For the anti-vibration in interferometry, a new simultaneous phase-shifting method based on Michelson polarization phase-shifting technique, is presented. In the corresponding set-up, a 2-dimentional grating is used. Through the grating, 4 diffracted beams of (±1,±1) orders are formed for the same diffractingFor the anti-vibration in interferometry, a new simultaneous phase-shifting method based on Michelson polarization phase-shifting technique, is presented. In the corresponding set-up, a 2-dimentional grating is used. Through the grating, 4 diffracted beams of (±1,±1) orders are formed for the same diffracting efficiency. Let each beam pass one of four polarizing plates, of which polarization directions differ in turn by 45°. So four interferograms which have 90° phase-shifting interval are obtained simultaneously. By using the 4-bucket algorithm, the wavefront of the test piece is derived. The intensity disuniform and phase shift error are analyzed. A spherical system of a sort is tested by the advanced system and ZYGO interferometer repectively. The results show that the difference of root-mean-square and peak to valley in the two experiments are 0.012λ and 0.051λ respectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 663 (2007)
Vertical Scanning White-Light Interferometry for Dimensional Characterization of Microelectromechanical System Devices
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
As microelectromechanical systems developed rapidly, the issue of mechanical characterization had emerged as a major consideration in device design and fabrication. Scanning white-light interferometry surface profiling for geometrical characterization and device inspection was proposed.The measurement system was based As microelectromechanical systems developed rapidly, the issue of mechanical characterization had emerged as a major consideration in device design and fabrication. Scanning white-light interferometry surface profiling for geometrical characterization and device inspection was proposed.The measurement system was based on a Mirau microscopic interferometer, using a piezo objective nano-positioner to realize accurate scanning in vertical direction in the range of 100 μm. The envelope peak position was extracted by fast Fourier transform processing method, and the whole information of device was obtained . Compared with phase shifting interferometry, it had a large measurement range. The measurement accuracy of the system is calibrated by a step height standard, then measuring repeatability was sub-nanometers level. A micro resonator and a micro pressure sensor are employed to illustrate the capabilities of scanning white-light interferometry as a measurement and process characterization tool..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 668 (2007)
Novel Angular Displacement Sensing Method with Resolution of 10-9 rad Magnitude
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A new technique for measuring micro angular displacement is presented. Based on a symmetrical metal-cladding waveguide, ultrahigh-order modes in the guiding layer(air gap) can be excited through prism coupling to serve as sensitive probes. When a micro angular displacement of the objective occurs, the thickness of the A new technique for measuring micro angular displacement is presented. Based on a symmetrical metal-cladding waveguide, ultrahigh-order modes in the guiding layer(air gap) can be excited through prism coupling to serve as sensitive probes. When a micro angular displacement of the objective occurs, the thickness of the air gap as well as the effective refractive index of the mode will be tuned. As a result, the intensity of the reflected beam will change remarkably with a magnitude proportional to the angular shift. It is shown through numerical calculation that the sensitivity is directly affected by the effective refractive index of the probe mode. A cantilever-like structure is employed in the experiment to generate controllable angular displacement, the mean sensitivity has been measured and found to be in well accordance with the results predicted by theory (relative error ～39%). It is theoretically and experimentally shown that, for components with a centimeter-sized rotational radius, an angular resolution of the order of 10-9 rad can be successfully achieved by this technique..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 673 (2007)
Integrated Optics
Alignment and Coupling between Planar Lightwave Circuit Chip and Wedge-Shaped Fiber
[in Chinese], [in Chinese], and [in Chinese]
An approach to alignment and coupling between wedge-shaped fiber (WSF) and semiconductor multiple quantum well planar lightwave circuit (PLC) chip integrated with two-dimensional spot size converter (SSC) was presented. Using staircase concatenation method (SCM), the optimum coupling conditions were achieved for wedge-An approach to alignment and coupling between wedge-shaped fiber (WSF) and semiconductor multiple quantum well planar lightwave circuit (PLC) chip integrated with two-dimensional spot size converter (SSC) was presented. Using staircase concatenation method (SCM), the optimum coupling conditions were achieved for wedge-shaped fiber wedge angle, cylindrical endface lens curvature radius, semimajor axis of planar lightwave circuit elliptical field, aspect ratio of planar lightwave circuit elliptical field, misalignment tolerance between wedge-shaped fiber and planar lightwave circuit to be 45°, 2.5 μm, 3.5 μm, 5 μ, 5.5 μm respectively. The output spot of wedge-shaped fiber was experimentally characterized by inverse deducing method (IDM). Compared with the staircase concatenation method computation, the error for the semimajor axis was 3.125%, while that for the semiminor axis was 0.8%. 1.55 μm signal laser was injected into planar lightwave circuit from SMF, tapered and lensed fiber (TLF), wedge-shaped fiber separately as planar lightwave circuit input fiber with the same SMF as output fiber. The coupling efficiency for wedge-shaped fiber was 24.827 dB and 16.22, dB higher than that of SMF and TLF, and therefore an experimental prototype of wedge-shaped fiber-planar lightwave circuit-SMF coupling linkage was established for pigtailed planar lightwave circuit packaging technique..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 680 (2007)
OPTICAL DATA STORAGE
Synchronizing Focus Error Detection of Dual-Pickup in Multi-Layer Data Storage System
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
To implement dual-pickup-head multilayer data storage system, it is necessary to measure the synchronizing focus error of the two pickup heads to validate the feasibility of the focus servo method. By using the ABCD transforming matrix method of the geometric optics, we calculate the relationship between the output eneTo implement dual-pickup-head multilayer data storage system, it is necessary to measure the synchronizing focus error of the two pickup heads to validate the feasibility of the focus servo method. By using the ABCD transforming matrix method of the geometric optics, we calculate the relationship between the output energy and the space interval of the two pickup heads. After confirming the detection system working in linear area, the coil motors of the two pickup heads were driven by sine signal with different frequency and record the output signals of the photo-detector under different movement states respectively, such as rest, single pickup head movement and dual-pickup-head synchronizing movement. The synchronizing focus error, which is caused by the characteristic parameter mismatch of the two pickup heads, could be obtained through frequency-domain analysis of these output signals. The experimental result shows that the amplitude of synchronizing focus error under 20 Hz is less than 1 μm, which could satisfy the focus servo requirement of the multilayer data storage system well..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 685 (2007)
Optical Devices
Steam-Redissolution Technique for Reduction of Polymer/Si Arrayed Waveguide Grating Loss
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Arrayed waveguide grating (AWG) is a key device in wavelength-division multiplexing (WDM) system. Polymer arrayed waveguide grating has recently attracted much attention due to its easier fabrication and higher-denisity device integration. Sidewall roughness scattering is one of the main loss factors for polymer arrayeArrayed waveguide grating (AWG) is a key device in wavelength-division multiplexing (WDM) system. Polymer arrayed waveguide grating has recently attracted much attention due to its easier fabrication and higher-denisity device integration. Sidewall roughness scattering is one of the main loss factors for polymer arrayed waveguide grating. Reduction of sidewall scattering loss plays an important role in fabricatiton of low-loss polymer arrayed waveguide grating. An efficient steam-redissolution technique is used to greatly reduce sidewall scattering loss in the polymer/Si arrayed waveguide grating. The mechanism of this technique is that saturated solvent molecules adsorb and get into sidewalls of waveguides and enhance their fluidity, and then reduce roughness of sidewalls. Smoother sidewalls are achieved and verified by a scanning electron microscopy. Both straight waveguides and arrayed waveguide grating devices are steam-redissolved and reduction of their sidewall scattering loss is further measured. The sidewall loss in straight polymer waveguide is decreased by 2.1 dB/cm, the insertion loss of an arrayed waveguide grating device is reduced by about 5.5 dB for the central channel and 6.7 dB for the edge channels, and the crosstalk is reduced by 2.5 dB after the steam-redissolution..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 690 (2007)
Numerical Analysis of Helium-Pressure Influence on Characteristics of Electro-Optic Switch Driven by Single-Pulse Process
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A one-dimensional numerical model for analyzing helium discharging of electro-optic switch driven by single-pulse process is proposed based on its microscopic physical mechanism. The influences of operating pressure on the characteristics of electro-optic switch driven by single-pulse process, such as gaseous breakdownA one-dimensional numerical model for analyzing helium discharging of electro-optic switch driven by single-pulse process is proposed based on its microscopic physical mechanism. The influences of operating pressure on the characteristics of electro-optic switch driven by single-pulse process, such as gaseous breakdown, discharging current, charging voltage on KDP crystal, switching efficiency, switching speed, electron temperature, plasma density are numerically analyzed. Calculated results demonstrate that switching speed is obviously influenced by operating pressure, and operating pressure influences switching efficiency weakly. Under the same driven pulse, switching speed becomes quicker when operating pressure is enhanced in the case of low operating pressure, and it will be slower when the pressure is enhanced in the case of high operating pressure. It can be proved from results that optimum operating pressure is between 1000 Pa and 4000 Pa for electro-optic switch with an aperture of 8 cm×8 cm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 695 (2007)
OPTOELECTRONICS
Method to Obtain the Transmission Characteristics of Photonic Crystal Defects being Asymmetrically Confined
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The transmission characteristics of the symmetrically confined photonic crystal (PC) defects had been detailedly investigated. By using the parameters of their defect modes, we can readily get the transmission characteristics of the asymmetrically confined photonic crystal defects. It shows that in the framework of couThe transmission characteristics of the symmetrically confined photonic crystal (PC) defects had been detailedly investigated. By using the parameters of their defect modes, we can readily get the transmission characteristics of the asymmetrically confined photonic crystal defects. It shows that in the framework of coupled-mode theory, an asymmetrically confined photonic crystal defect can be considered as the combination of two different symmetrically confined photonic crystal defects, and its transmission characteristics are decided by the decay-rates of the two involved symmetrically confined defects. All the analyses are in a good agreement with the simulation based on the finite-difference time-domain technique..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 706 (2007)
Polarization-Induced Fading Elimination Technique in Brillouin Optical Time-Domain Analysis Sensor
[in Chinese], and [in Chinese]
Because stimulated Brillouin scattering is polarization related, in Brillouin optical time-domain analysis (BOTDA) sensing system, the steady measurement of sensing signals is seriously affected by the random change of polarization state of pump light and probe light, which causes the measured signal fluctuant. ThroughBecause stimulated Brillouin scattering is polarization related, in Brillouin optical time-domain analysis (BOTDA) sensing system, the steady measurement of sensing signals is seriously affected by the random change of polarization state of pump light and probe light, which causes the measured signal fluctuant. Through constructing coupling equations about the polarization states of pump light and probe light, we deduce the function about probe light intensity referred to the polarization state of pump light and probe light. And a novel method, called polarization expanding receiving method, is proposed to eliminate the polarization related signal fading. Numerically simulated results of coupling equations prove that the polarization expanding receiving technique is feasible for Brillouin optical time-domain analysis (BOTDA), and the theoretical analysis is correct. Finally, a primary experimental result with the proposed method is present, which is coincident with the theoretical and simulating results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 711 (2007)
Physical Optics
Study on the Transmittance of Marple-Hess Prism Undulating with the Incident Angle
[in Chinese], [in Chinese], and [in Chinese]
In order to study the change of Marple-Hess prism's transmittance with the incident angle observed in the experiment, all parameters related the prism are put in the mathematical model of three-point coaxial system. The Fresnel formula and multiple-beam interference theory are used to study the interference's eIn order to study the change of Marple-Hess prism's transmittance with the incident angle observed in the experiment, all parameters related the prism are put in the mathematical model of three-point coaxial system. The Fresnel formula and multiple-beam interference theory are used to study the interference's effect on the transmittance in detail which is caused by first order beam and other order beams produced by reflection of air gap. A precise transmittance formula is deduced which can explain the phenomena that transmittance undulates periodically along with the plane incident angle's continuous change in the experiment. The theoretical curves of transmittance undulating with azimuth angle is also drawn, which indicate that the change of transmittance with azimuth angle is periodical, and the frequency and amplitude of the transmittance's fluctuation increase with the increase of plane incident angle's absolute value..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 716 (2007)
Quantum Optics
Phase Properties for the Photon-Added Even and Odd Coherent States
[in Chinese], [in Chinese], and [in Chinese]
By virtue of the Pegg-Barnett phase operator formalism and the numerical computation method, the phase probability distributions and the squeezed properties of number operator and phase operator for the photon-added even and odd coherent states are investigated. The results show that the phase probability distributionsBy virtue of the Pegg-Barnett phase operator formalism and the numerical computation method, the phase probability distributions and the squeezed properties of number operator and phase operator for the photon-added even and odd coherent states are investigated. The results show that the phase probability distributions, which exhibit different quantum phase information and interference features, of the photon-added even and odd coherent states are different from those of the usual even and odd coherent states and even and odd nonlinear coherent states. We also find that the photon-added even and odd coherent states exhibit squeezed effects in the directions of the number operator and phase operator at different ranges of the parameter α..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 721 (2007)
Statistic Properties of Photon in the System of the Two-Mode Entangled Coherent Field Interacting with Atoms in Bell States in Kerr Medium
[in Chinese], [in Chinese], and [in Chinese]
The statistic properties of photon in the system of two-mode entangled coherent field interacting with two identical two-level atoms in the Bell state in Kerr medium are investigated by means of quantum theory and numerical method. Induced by the atomic initial state, mean photon numbers of field, the degree of the entThe statistic properties of photon in the system of two-mode entangled coherent field interacting with two identical two-level atoms in the Bell state in Kerr medium are investigated by means of quantum theory and numerical method. Induced by the atomic initial state, mean photon numbers of field, the degree of the entanglement for the entangled coherent fields, and the coupling strength of the Kerr medium with the light field, the effects on the statistic properties of photon are discussed. The results indicate that, if the medium is not present, photon anti-bunching effect does not appear for the Bell state β00〉 or β10〉, there can appear the photon anti-bunching effect under some conditions for the Bell state β01〉 or β11〉. If the medium is considered, there can appear the photon anti-bunching effect for all of initial states. In the case, the number of occurring , interval and intensity of the photon anti-bunching effects sensitively depend on the coupling strength of the Kerr medium with the light field, the mean photon numbers and the degree of entanglement of the two-mode entangled coherent field..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 727 (2007)
Thin Films
SiC/Mg Multilayer Film Reflective Mirror at 30.4 nm
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The He-Ⅱ spectrum at the wavelength of 30.4 nm is a key spectrum in extreme ultraviolet astronomic observation, and multilayer film reflective mirror are usually adapted in the observation. The reflection at the wavelength of 30.4 nm of the multilayer films composed of SiC/Mg, B4C/Mg, C/Mg, C/Al, Mo/Si, B4C/SI, SiC/Si,The He-Ⅱ spectrum at the wavelength of 30.4 nm is a key spectrum in extreme ultraviolet astronomic observation, and multilayer film reflective mirror are usually adapted in the observation. The reflection at the wavelength of 30.4 nm of the multilayer films composed of SiC/Mg, B4C/Mg, C/Mg, C/Al, Mo/Si, B4C/SI, SiC/Si, C/Si, Sc/Si is studied. Based on the optimization of largest reflectivity and narrowest width for the multilayer film mirror, SiC/Mg multilayer is selected as the film material, SiC/Mg multilayer films are fabricated by using magnetron sputtering. The periodical thickness of the SiC/Mg multilayer film is measured by X-ray diffractometer, and the reflectivity was measured by the reflectometer in synchrotron radiation laboratory. At incidence angle of 12°, the reflectivity of 38.0% is obtained at the wavelength of 30.4 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 735 (2007)
Structure and Optical properties of ZnO Films DC Reactively Sputtered at Different Oxygen Partial Pressure
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Thin wurtzite (002) textured ZnO films were deposited on the quartz substrate by DC reactive sputtering with a Zn target at room temperature under different oxygen ratios. The deposition rate of the film will get slow as the oxygen ratio becomes greater. There is a turning point of the oxygen partial pressure between 2Thin wurtzite (002) textured ZnO films were deposited on the quartz substrate by DC reactive sputtering with a Zn target at room temperature under different oxygen ratios. The deposition rate of the film will get slow as the oxygen ratio becomes greater. There is a turning point of the oxygen partial pressure between 20% and 30%. On the left side of the point, the deposition rate goes slower, meanwhile, the decrease of deposition rate gets even on the right side. When the oxygen ratio gets more than 30%, the oxidation of Zn is completed on the target surface. The optical properties are investigated with single oscillator model, and the grain size and stress are analyzed with X-ray diffraction. It is proved that ZnO films with good transparence and high electrical resistivity could be obtained while the oxygen ratio is more than 20%. The refractive index, spacing and stress of ZnO film will increase as the oxygen ratio increases, which is theoretically explained with the method of film growing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 739 (2007)
Vision, Color, and Visual Optics
Measurement of Luminance Contrast Sensitivity Function of Human Visual System on Cathode Ray Tube Display
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The characteristics of the human visual system (HVS) are the basis for image technology of display, processing and understanding, and the contrast sensitivity function (CSF) is one of important and special characteristics of HVS. CSF data under the computer display environment has practical applications to the image teThe characteristics of the human visual system (HVS) are the basis for image technology of display, processing and understanding, and the contrast sensitivity function (CSF) is one of important and special characteristics of HVS. CSF data under the computer display environment has practical applications to the image technologies. Luminance CSF was measured for square-wave patterns on a CRT display, and a psychophysical method for determination of contrast threshold “multi-contrast interactive threshold determination (MITD)” was presented and adopted. Measurements were done for three mean luminances of 10 cd/m2, 60 cd/m2, 90 cd/m2 and eleven spatial frequencies of 0.41 cpd, 0.82 cpd, 1.23 cpd, 1.97 cpd, 3.08 cpd, 3.79 cpd, 4.93 cpd, 7.04 cpd, 9.86 cpd, 16.43 cpd, 24.64 cpd. Measurement results were compared with previous ones that had been measured with the optical apparatus..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 744 (2007)
X-Ray Optics
Absorption, Refraction and Extinction Contrast Computerized Tomography of X-Ray Diffraction Enhanced Imaging Method
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The X-ray phase-contrast imaging method, which images the object by recording the phase change after X-ray passing through the object, is a new X-ray imaging technique. This new imaging method can provide higher contrast and spatial resolution than the conventional X-ray absorption imaging method. Diffraction enhanced The X-ray phase-contrast imaging method, which images the object by recording the phase change after X-ray passing through the object, is a new X-ray imaging technique. This new imaging method can provide higher contrast and spatial resolution than the conventional X-ray absorption imaging method. Diffraction enhanced imaging (DEI) method is one of the four phase-contrast X-ray imaging techniques. DEI method can extract the absorption, refraction and extinction information of the object with an analyzer crystal placed between the object and detector. DEI method is combined with the computed tomography (CT), EDI-CT, to construct the insect sample——a bee with its absorption, extinction and refraction information with filtered back algorithm and Radon transform method. The results obtained by DEI-CT are better than the absorption CT, and proves that the DEI-CT is superior to the conventional CT..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 27, Issue 4, 749 (2007)
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