Journals >Chinese Optics Letters
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2005
Volume: 3 Issue 2
20 Article(s)
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Diffraction and Gratings
In-situ end-point detection during ion-beam etching of multilayer dielectric gratings
Hua Lin, Lifeng Li, and Lijiang Zeng
An in-situ end-point detection technique for ion-beam etching is presented. A laser beam of the same wavelength and polarization as those in the intended application of the grating is fed into the vacuum chamber, and the beam retro-diffracted by the grating under etching is extracted and detected outside the chamber. TAn in-situ end-point detection technique for ion-beam etching is presented. A laser beam of the same wavelength and polarization as those in the intended application of the grating is fed into the vacuum chamber, and the beam retro-diffracted by the grating under etching is extracted and detected outside the chamber. This arrangement greatly simplifies the end-point detection. Modeling the grating diffraction with a rigorous diffraction grating computer program, we can satisfactorily simulate the evolution of the diffraction intensity during the etching process and consequently, we can accurately predict the end-point. Employing the proposed technique, we have reproducibly fabricated multilayer dielectric gratings with diffraction efficiencies of more than 92%..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0263 (2005)
Image Processing
Color and neighbor edge directional difference feature for image retrieval
Chaobing Huang, Shengsheng Yu, Jingli Zhou, and Hongwei Lu
A novel image feature termed neighbor edge directional difference unit histogram is proposed, in which the neighbor edge directional difference unit is defined and computed for every pixel in the image, and is used to generate the neighbor edge directional difference unit histogram. This histogram and color histogram aA novel image feature termed neighbor edge directional difference unit histogram is proposed, in which the neighbor edge directional difference unit is defined and computed for every pixel in the image, and is used to generate the neighbor edge directional difference unit histogram. This histogram and color histogram are used as feature indexes to retrieve color image. The feature is invariant to image scaling and translation and has more powerful descriptive for the natural color images. Experimental results show that the feature can achieve better retrieval performance than other color-spatial features..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0266 (2005)
A universal method for camera calibration in UITS scenes
Zhaoxue Chen, and Pengfei Shi
A universal approach to camera calibration based on features of some representative lines on traffic ground is presented. It uses only a set of three parallel edges with known intervals and one of their intersected lines with known slope to gain the focal length and orientation parameters of a camera. A set of equationA universal approach to camera calibration based on features of some representative lines on traffic ground is presented. It uses only a set of three parallel edges with known intervals and one of their intersected lines with known slope to gain the focal length and orientation parameters of a camera. A set of equations that computes related camera parameters has been derived from geometric properties of the calibration pattern. With accurate analytical implementation, precision of the approach is only decided by accuracy of the calibration target selecting. Final experimental results have showed its validity by a snapshot from real automatic visual traffic surveillance (AVTS) scenes..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0269 (2005)
Imaging Systems
Simulation study of the NAσ's dependence of DOF for 193-nm immersion lithography at 65-nm node
Guosheng Huang, and Yanqiu Li
Recently, ArF immersion lithography has been considered as a promising method after ArF dry lithography by a factor of refractive index n of the liquid filled into the space between the bottom lens and wafer, in the case of 193-nm exposure tools, water (n = 1.44) has been found as the best liquid. We explore the NAσRecently, ArF immersion lithography has been considered as a promising method after ArF dry lithography by a factor of refractive index n of the liquid filled into the space between the bottom lens and wafer, in the case of 193-nm exposure tools, water (n = 1.44) has been found as the best liquid. We explore the NAσ's dependence of depth of focus (DOF) under 3/4 annular and 3/4 quasar illumination by resist imaging simulation. Line/space pairs of line-to-space ratios 1:1, 1:2, 1:4 on binary mask are considered. Finally, we explored the high NA's dependency of DOF and gave the explanation for the peak value of DOF through three-beam imaging process, MicroCruiser 2.0, Prolith version 8.0.2 and k_2 factor based on the Rayleigh equation..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0273 (2005)
Lasers and Laser Optics
RF excited diffusively cooled all-metal slab waveguide CO2 laser
Jianguo Xin, Shuna Yao, Ning Su, Zhiming Li, and Yanhong Zhong
In this paper, a new type of radio frequency (RF) excited diffusively cooled all-metal slab waveguide CO2 laser is presented, in which the waveguide channel is constructed by two aluminum side walls and two aluminum electrodes, the discharge is confined in the slab waveguide channel in terms of the voltage division strIn this paper, a new type of radio frequency (RF) excited diffusively cooled all-metal slab waveguide CO2 laser is presented, in which the waveguide channel is constructed by two aluminum side walls and two aluminum electrodes, the discharge is confined in the slab waveguide channel in terms of the voltage division structure. From this type of structure, 127-W laser power is obtained..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0283 (2005)
Influence of the KTP crystal boundary temperature on conversion efficiency in high power green laser
Degang Xu, Jianquan Yao, Baigang Zhang, Shiyong Zhao, Rui Zhou, Xin Ding, Wuqi Wen, and Peng Wang
The influence of the KTiOPO4 (KTP) crystal boundary temperature on conversion efficiency in high power green laser has been studied theoretically and experimentally. Temperature distribution inside the KTP crystal has been analyzed by solving the thermal conductivity equation. From the temperature distribution inside tThe influence of the KTiOPO4 (KTP) crystal boundary temperature on conversion efficiency in high power green laser has been studied theoretically and experimentally. Temperature distribution inside the KTP crystal has been analyzed by solving the thermal conductivity equation. From the temperature distribution inside the KTP crystal, we have calculated the optimal phase-matching angles of the type-II KTP crystal as a function of temperature. The second-harmonic conversion efficiency as a function of temperature has also been calculated. In the experiment, two KTP crystals with different phase-matching angles were used in the intrcavity-frequency-doubled resonator. When the boundary temperature of KTP-A (φ = 23.6o, θ = 90o under the condition of 27 oC temperature) was setting at 4 oC, a maximum green light power of 104 W was generated at repetition rate of 20.7 kHz and pulse width of 132 nm with pumping current of laser diode of 18.3 A, leading to 10.2% optical-to-optical conversion efficiency. When KTP-B crystal (φ = 24.68o, θ = 90o under the condition of 80 oC temperature) was employed, an average output power of 110 W at 532 nm has been achieved with values of 11.5% and 2% for the optical-to-optical efficiency and the instability, respectively. The optimal boundary temperature of this KTP crystal has been found to be 48.8 oC..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0285 (2005)
Highly efficient Nd:YAG ceramic CW laser with 59.8% slope-efficiency
Yunfeng Qi, Qihong Lou, Haixia Ma, and Jingxing Dong
In this paper, a highly efficient Ti:sapphire end-pumped 1 at.-% Nd:YAG ceramic laser that is comparable in efficiency with Nd:YAG single crystal lasers has been developed. Optical absorption and emission spectra for Nd:YAG ceramics have been measured. With 673-mW pumping, 295-mW laser output at 1064 nm has been obtainIn this paper, a highly efficient Ti:sapphire end-pumped 1 at.-% Nd:YAG ceramic laser that is comparable in efficiency with Nd:YAG single crystal lasers has been developed. Optical absorption and emission spectra for Nd:YAG ceramics have been measured. With 673-mW pumping, 295-mW laser output at 1064 nm has been obtained. The laser threshold is only 13 mW. Deducted the transmitted light, the corresponding optical-to-optical conversion efficiency is 58.4%. The lasing characteristics of Nd:YAG ceramic are nearly equal to those of Nd:YAG single crystal..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0289 (2005)
All solid-state, injection-seeded Ti:sapphire ring laser
Ting Yu, Weibiao Chen, Jun Zhou, Jinzi Bi, and Junwen Cui
In this letter, we present an all solid-state, injection-seeded Ti:sapphire laser. The laser is pumped by a laser diode pumped frequency-doubled Nd:YAG laser, and injection-seeded by an external cavity laser diode with the wavelength between 770 and 780 nm. The single longitude mode and the doubling efficiency of the lIn this letter, we present an all solid-state, injection-seeded Ti:sapphire laser. The laser is pumped by a laser diode pumped frequency-doubled Nd:YAG laser, and injection-seeded by an external cavity laser diode with the wavelength between 770 and 780 nm. The single longitude mode and the doubling efficiency of the laser are obtained after injection seeding. The experimental setup and relative results are reported. It is a good candidate laser source for mobile differential absorption lidar (DIAL) system..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0292 (2005)
All solid-state passively Q-switched frequency-doubled intra-cavity Nd:GdVO4/KTP laser
Chuanbo Gong, Changshui Chen, Bian Wu, Qingli Zhang, Xianyou Wu, and Shaotang Yin
In this paper, laser frequency-double and passive Q-switching are studied. The optimum coupling at end-pump and optimum design of resonator are also investigated. The maximum output power of TEM00 is 1.68 W at 1.06-μm wavelength. Optic-optic conversion efficiency is 48.6%, and the slope efficiency is 56.3%. The maximumIn this paper, laser frequency-double and passive Q-switching are studied. The optimum coupling at end-pump and optimum design of resonator are also investigated. The maximum output power of TEM00 is 1.68 W at 1.06-μm wavelength. Optic-optic conversion efficiency is 48.6%, and the slope efficiency is 56.3%. The maximum output of green light is 0.235 W. The smallest pulse-width of green light is 27.42 ns, optic-optic conversion efficiency of green light is 7%, and beam quality factor M2<1.2. Thermal lens effect is discussed..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0294 (2005)
The application of arbitrary incidence laser beams heat treatment temperature field calculation formulas
Kun Ma, Junchang Li, Zebin Fan, Jinbin Gui, Yingxiong Qin, and Qiguang Zheng
Based on the calculation formulas of heat treatment temperature field for an arbitrary incident laser intensity distribution, the transformation intensity distribution of CO2 laser beam passing an integrating mirror is studied theoretically and experimentally. The derived formulas are applied in laser heat treatment reBased on the calculation formulas of heat treatment temperature field for an arbitrary incident laser intensity distribution, the transformation intensity distribution of CO2 laser beam passing an integrating mirror is studied theoretically and experimentally. The derived formulas are applied in laser heat treatment research which is transformed by optical system, and the theoretical calculation results are compared with experimental results. It is shown that the formulas can be used to calculate the laser heat treatment temperature field accurately, and the calculation speed is obviously faster than the numerical calculation methods with the same precision. The calculation software can be used to select proper experiment parameters..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0297 (2005)
Materials
Planar waveguides formed in a new chemically stable Er(3+)/Yb(3+) co-doped phosphate glass
Shilong Zhao, Baoyu Chen, Junjiang Hu, and Lili Hu
A new Er(3+)/Yb(3+) co-doped phosphate glass has been prepared, which exhibits good chemical durability and spectralproperties. Planar graded index waveguides have been fabricated in the glass by (Ag+)-Na(+) ion exchange in a mixed melt of silver nitrate and potassium nitrate. Ion exchange is carried out by varying theA new Er(3+)/Yb(3+) co-doped phosphate glass has been prepared, which exhibits good chemical durability and spectralproperties. Planar graded index waveguides have been fabricated in the glass by (Ag+)-Na(+) ion exchange in a mixed melt of silver nitrate and potassium nitrate. Ion exchange is carried out by varying the process parameters such as temperature, diffusion time, and molten salt compositions. The diffusion parameters, diffusion coefficients, and activation energy are determined by the guidelines of fabricated waveguides, which are determined by the input prism coupling technique..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 02101 (2005)
Intense frequency upconversion fluorescence of Er(3+)/Yb(3+) co-doped lithium-strontium-lead-bismuth glasses
Hongtao Sun, Shiqing Xu, Baoyu Chen, Shixun Dai, Shilong Zhao1, and Zhonghong Jiang
Infrared-to-visible upconversion fluorescence of Er(3+)/Yb(3+) co-doped lithium-strontium-lead-bismuth (LSPB) glasses for developing potential upconversion lasers has been studied under 975-nm excitation. Based on the results of energy transfer efficiency and upconversion spectra, the optimal Yb(3+)-Er(3+) concentratioInfrared-to-visible upconversion fluorescence of Er(3+)/Yb(3+) co-doped lithium-strontium-lead-bismuth (LSPB) glasses for developing potential upconversion lasers has been studied under 975-nm excitation. Based on the results of energy transfer efficiency and upconversion spectra, the optimal Yb(3+)-Er(3+) concentration ratio is found to be 5:1. Intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions 2H_(11/2)-->4I_(15/2), 4S_(3/2)-->4I_(15/2), and 4F_(9/2)-->4I_(15/2), respectively, were observed. The quadratic dependence of the 525-, 546-, and 657-nm emissions on excitation power indicates that a two-photon absorption process occurs under 975-nm excitation. The high-populated 4I_(11/2) level is supposed to serve as the intermediate state responsible for the upconversion processes. The intense upconversion luminescence of Er(3+)/Yb(3+) co-doped LSPB glasses may be a potentially useful material for developing upconversion optical devices..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 02103 (2005)
Nonlinear Optics
Polarization-independent wavelength conversion using a single semiconductor optical amplifier
Xiaofeng Xu, Jue Wei, Zhihui Kang, Yun Jiang, Weizhong Zhu1, and Jinyue Gao
Polarization-independent wavelength conversion is demonstrated by using four-wave mixing (FWM) in a single semiconductor optical amplifier (SOA). In this scheme, all the incident fields are split into two orthogonal-polarized parts by polarizing beam splitters (PBS). Each of the two parts is then transmitted into one fPolarization-independent wavelength conversion is demonstrated by using four-wave mixing (FWM) in a single semiconductor optical amplifier (SOA). In this scheme, all the incident fields are split into two orthogonal-polarized parts by polarizing beam splitters (PBS). Each of the two parts is then transmitted into one facet of the SOA and they are counter-propagating through the same amplifier. Wavelength conversion with the polarization sensitivity less than 1.3 dB is obtained over a range from 1510 to 1620 nm..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 02110 (2005)
Thin Films
Newly designed multilayer thin film mirror for dispersion compensation in Ti:sapphire femtosecond lasers
Chunyan Liao, Jianda Shao, Jianbing Huang, Zhengxiu Fan, and Hongbo He
There are two different effects to generate group delay dispersion by multilayer thin film mirrors: chirper effect and Gires-Tournois effect. Both effects are employed to introduce desired dispersion in the designed mirror. Thus the designed mirror provides large dispersion throughout broad waveband. Such mirror can beThere are two different effects to generate group delay dispersion by multilayer thin film mirrors: chirper effect and Gires-Tournois effect. Both effects are employed to introduce desired dispersion in the designed mirror. Thus the designed mirror provides large dispersion throughout broad waveband. Such mirror can be used for dispersion compensation in Ti:sapphire femtosecond lasers. Most group delay dispersion of a 5-mm Ti:sapphire crystal can be compensated perfectly with only four bounces of the designed mirror..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 02122 (2005)
Instrumentation, Measurement, and Metrology
Laser micro-impulse torsion pendulum
Jing Li, and Zhiping Tang
In order to investigate the feasibility regarding micro-satellite posture steering by laser micro-propulsion, a laser torsion pendulum has been set up so as to get first-hand basic physical and mechanical parameters on laser micro-propulsion. The instrumentation consists of the optical, mechanical, and electrical sub-sIn order to investigate the feasibility regarding micro-satellite posture steering by laser micro-propulsion, a laser torsion pendulum has been set up so as to get first-hand basic physical and mechanical parameters on laser micro-propulsion. The instrumentation consists of the optical, mechanical, and electrical sub-systems. The optical system includes the main beam optics, the measuring optics, and the observation optics. The mechanical system includes the gyration apparatus, transverse translation stage, vertical translator, focal lenses translator, calibration pendulum translator, and vacuum chamber. For the electrical system a computer is used to control stepping motors to drive the above moving apparatuses. With this instrument the calibration experiment and laser ablation experiment have been carried out. The experimental results demonstrate that the instrument has the capacity to measure impulse down to 10^(-8) N.s with an error of about 10.4%, which can satisfy the requirement of micro-impulse measurement..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0276 (2005)
A new interpolating method based on the variation of spectra energy using CMOS array
Tianjin Tang, Xiangqun Cao, Hongqiu Chen, and Bin Lin
A new interpolating method to enhance the resolution of gratings using complementary metal-oxide semiconductor (CMOS) according to the variation of some specified spectral light intensities during the motion of scale grating in a periodic separation is proposed. CMOS image sensor (pixel array 648*488) was also introducA new interpolating method to enhance the resolution of gratings using complementary metal-oxide semiconductor (CMOS) according to the variation of some specified spectral light intensities during the motion of scale grating in a periodic separation is proposed. CMOS image sensor (pixel array 648*488) was also introduced as receiving device and its stability was verified experimentally. Many factors in the experiment were analyzed theoretically and contrasted with experiment. The advantages of this novel method were featured by CMOS and the specified spectral variation of the energy distribution was discussed..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 0280 (2005)
Microscopy
Near-field lithography on the azobenzene polymer liquid crystal films
Douguo Zhang, Pei Wang, Yonghua Lu, Ming Bai, Jun Yang, Lin Tang, Jiangying Zhang, Hai Ming, Qijin Zhang, Jian Liu, Zebo Zhang, Li Cao, and Anlian Pan
In this article, we reported near-field research on azobenzene polymer liquid crystal films using scanning near-field optical microscopy (SNOM). Optical writing and subsequently topographic reading of the patterns with subwavelength resolution were carried out in our experiments. Nanometer scale dots and lines were sucIn this article, we reported near-field research on azobenzene polymer liquid crystal films using scanning near-field optical microscopy (SNOM). Optical writing and subsequently topographic reading of the patterns with subwavelength resolution were carried out in our experiments. Nanometer scale dots and lines were successfully fabricated on the films and the smallest dot diameter is about 120 nm. The width of the line fabricated is about 250 nm. This method is also a choice for nanolithography. The mechanism of the surface deformation on the polymer films was briefly analyzed from the viewpoint of gradient force in the optical near field. The intensity distribution of the electric field near the tip aperture was numerically simulated using finite-difference time-domain (FDTD) method and the numerical simulation results were consistent with the experimental results..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 02107 (2005)
OPTICAL DATA STORAGE
Read-only memory disk with AgOx super-resolution mask layer
Feng Zhang, Yang Wang, Wendong Xu, Hongren Shi, and Fuxi Gan
A novel read-only memory (ROM) disk with an AgOx mask layer was proposed and studied in this letter. The AgOx films sputtered on the premastered substrates, with pits depth of 50 nm and pits length of 380 nm, were studied by an atomic force microscopy. The transmittances of these AgOx films were also measured by a specA novel read-only memory (ROM) disk with an AgOx mask layer was proposed and studied in this letter. The AgOx films sputtered on the premastered substrates, with pits depth of 50 nm and pits length of 380 nm, were studied by an atomic force microscopy. The transmittances of these AgOx films were also measured by a spectrophotometer. Disk measurement was carried out by a dynamic setup with a laser wavelength of 632.8 nm and a lens numerical aperture (NA) of 0.40. The readout resolution limit of this setup was λ/(4NA) (400 nm). Results showed that the super-resolution readout happened only when the oxygen flow ratios were at suitable values for these disks. The best super-resolution performance was achieved at the oxygen flow ratio of 0.5 with the smoothest film surface. The super-resolution readout mechanism of these ROM disks was analyzed as well..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 02113 (2005)
Spectroscopy
Measurement of borneol based on infrared spectrometry
Xiaoyu Gu, Yan Wang, Huili Sun, and Kexin Xu
The infrared spectrometry contains multiple information of the sample, and it is easy to be applied to on-line measurement. To Chinese medicine, this technology can improve the standard of quality control and accelerate the modernization course. In this paper, we investigate the spectral characteristics of borneol, an The infrared spectrometry contains multiple information of the sample, and it is easy to be applied to on-line measurement. To Chinese medicine, this technology can improve the standard of quality control and accelerate the modernization course. In this paper, we investigate the spectral characteristics of borneol, an effective ingredient in many Chinese medicines. The following results are achieved. In middle infrared (MIR) region, utilizing the linear relationship between absorption and concentration, the concentration of borneol with relative error within 4.30% in the strongest absorption region (2950-2970 cm(-1)) is measured; in near infrared (NIR) region, the predicted concentrations of borneol are calculated by using partial least squares (PLS) regression analysis, in which the wavelengths are selected by genetic algorithm (GA) from the absorption bands of borneol in NIR region. The predicted relative error of calibration model is less than 2%. This result shows that PLS regression analysis combining genetic algorithm is a good method to improve prediction and reduce data in NIR region..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 02116 (2005)
Photo-acoustic spectrum and detection of nitrogen dioxide
Guiyin Zhang, Lianshui Zhang, and Xiaofeng Han
The photo-acoustic (PA) spectrum of nitrogen dioxide (NO2) in the range of 420-520 nm with a Nd:YAG pumped optical parametric generator and amplifier as radiation source is presented. The spectrum has a characteristic of banded structure superimposed on continuum. The banded structure of the spectrum can be assigned toThe photo-acoustic (PA) spectrum of nitrogen dioxide (NO2) in the range of 420-520 nm with a Nd:YAG pumped optical parametric generator and amplifier as radiation source is presented. The spectrum has a characteristic of banded structure superimposed on continuum. The banded structure of the spectrum can be assigned to NO2 B2B1<--X2A1 transition. While the continual one comes from the chaos states of the first excited state A2B2 and the high vibration levels of the ground state X2A1. The relationship of PA signal with buffer gas pressure and NO2 concentration is measured. The PA signal intensity increases with buffer gas pressure and almost is invariable when the buffer gas pressure is more than 3.00*10^(4) Pa. The PA signal intensity has linearity with NO2 concentration. The detection limit is about 2*10^(-5) on the basis of SNR = 1, however lower value of the detection limit can be expected by improving the apparatus properties..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 2, 02119 (2005)
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