Journals >Chinese Optics Letters
Contents
2005
Volume: 3 Issue 8
20 Article(s)
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Fiber Optics and Optical Communications
8*10-Gb/s transmission system over 1500 km on G.652 fiber dispersion compensated by chirped fiber gratings
Zhongwei Tan, Yan Liu, Yong Chen, Jihong Cao, Xiaowei Dong, Lina Ma, Deyuan Chang, Tigang Ning, and Shuisheng Jian
A low cost 8*10-Gb/s transmission system over 1500 km on conventional fiber using chirped fiber Bragg grating (CFBG) as dispersion compensator is demonstrated. The bit error rate (BER) below 10^(-10) at 1500 km is obtained. The channel spacing is 0.8 nm and the optical amplifier spacing is 100 km. Only 16 erbium-doped A low cost 8*10-Gb/s transmission system over 1500 km on conventional fiber using chirped fiber Bragg grating (CFBG) as dispersion compensator is demonstrated. The bit error rate (BER) below 10^(-10) at 1500 km is obtained. The channel spacing is 0.8 nm and the optical amplifier spacing is 100 km. Only 16 erbium-doped fiber amplifiers (EDFAs) are used..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08441 (2005)
Compact first and second order polarization mode dispersion emulator
Yang Zhang, Shiguang Li, and Changxi Yang
We propose a 1st and 2nd order polarization mode dispersion emulator (PMDE) with one variable differential group delay (DGD) element using birefringence crystals and four polarization controllers (PCs). Monte Carlo simulations demonstrate that the output 1st and 2nd order polarization mode dispersion (PMD) generated byWe propose a 1st and 2nd order polarization mode dispersion emulator (PMDE) with one variable differential group delay (DGD) element using birefringence crystals and four polarization controllers (PCs). Monte Carlo simulations demonstrate that the output 1st and 2nd order polarization mode dispersion (PMD) generated by the PMDE consists with statistic theory. Compared with former PMDEs, this design is tunable, lower-cost, and more integrated for fabrication, which shows response time of 150 μs, response frequency of 3.8 kHz, working wavelength of 1550 nm, total power consumption of less than 3 W, working range of 0---84 ps and 0---3600 ps2 for 1st and 2nd order PMD emulation, respectively. Also, it is programmable and can be controlled by either singlechip or computer. It can be applied to study the outage probability of optical communication systems due to PMD effect and the effectiveness of PMD compensation..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08444 (2005)
Image Processing
Transfer color to night vision images
Shaoyuan Sun, Zhongliang Jing, Gang Liu, and Zhenhua Li
Natural color appearance is the key problem of color night vision field. In this paper, the color mood of daytime color image is transferred to the monochromic night vision image. This method gives the night image a natural color appearance. For each pixel in the night vision image, the best matching pixel in the colorNatural color appearance is the key problem of color night vision field. In this paper, the color mood of daytime color image is transferred to the monochromic night vision image. This method gives the night image a natural color appearance. For each pixel in the night vision image, the best matching pixel in the color image is found based on texture similarity measure. Entropy, energy, contrast, homogeneity, and correlation features based on co-occurrence matrix are combined as texture similarity measure to find the corresponding pixels between the two images. We use a genetic algorithm (GA) to find the optimistic weighting factors assigned to the five different features. GA is also employed in searching the matching pixels to make the color transfer algorithm faster. When the best matching pixel in the color image is found, the chromaticity values are transferred to the corresponding pixel of the night vision image. The experiment results demonstrate the efficiency of this natural color transfer technique..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08448 (2005)
MAP-based infrared image expansion
Nan Zhang, Weiqi Jin, Binghua Su, Yangyang Liu, and Hua Chen
Image expansion plays a very important role in image analysis. Common methods of image expansion, such as the zero-order hold method, may generate a visual mosaic to the expanded image, linear and cubic spline interpolation may blur the image data at peripheral regions. Since infrared images have the characteristics ofImage expansion plays a very important role in image analysis. Common methods of image expansion, such as the zero-order hold method, may generate a visual mosaic to the expanded image, linear and cubic spline interpolation may blur the image data at peripheral regions. Since infrared images have the characteristics of low contrast and low signal-to-noise ratio (SNR), the expanded images derived from common methods are not satisfactory. As shown in the analysis of the course from images with low resolution to those with high resolution, the expansion of image is found to be an ill-posed inverse problem. An image interpolation algorithm based on MAP estimation under Bayesian framework is proposed in this paper, which can effectively preserve the discontinuities in the original image. Experimental results demonstrate that the expanded images by this method are visually and quantitatively (analyzed by using the criteria of mean squared error (MSE) and mean absolute error (MAE)) superior to the images expanded by common methods of linear interpolation. Even in expansion of infrared images, this method can also give good results. An analysis about choosing regularization parameter α in this algorithm is given..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08451 (2005)
Integrated Optics
Offset quantum-well method for tunable distributed Bragg reflector lasers and electro-absorption modulated distributed feedback lasers
Qiang Kan, Ying Ding, Lingjuan Zhao, Hongliang Zhu, Fan Zhou, Lufeng Wang, Baojun Wang, and Wei Wang
A two-section offset quantum-well structure tunable laser with a tuning range of 7 nm was fabricated using offset quantum-well method. The distributed Bragg reflector (DBR) was realized just by selectively wet etching the multiquantum-well (MQW) layer above the quaternary lower waveguide. A threshold current of 32 mA aA two-section offset quantum-well structure tunable laser with a tuning range of 7 nm was fabricated using offset quantum-well method. The distributed Bragg reflector (DBR) was realized just by selectively wet etching the multiquantum-well (MQW) layer above the quaternary lower waveguide. A threshold current of 32 mA and an output power of 9 mW at 100 mA were achieved. Furthermore, with this offset structure method, a distributed feedback (DFB) laser was integrated with an electro-absorption modulator (EAM), which was capable of producing 20 dB of optical extinction..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08455 (2005)
Lasers and Laser Optics
High-power double-clad large-mode-area photonic crystal fiber laser
Kang Li, Yishan Wang, Wei Zhao, Guofu Chen, Qinjun Peng, Dafu Cui, and Zuyan Xu
A high power double-clad ytterbium-doped large-mode-area photonic crystal fiber (LMA PCF) laser was demonstrated using a unique Fabry-Perot (F-P) configuration. The pump source is a fiber coupled diode array operating at 976 nm. A continuous wave (CW) output power of 50 W at ~1.04 μm with a slope efficiency of 76.3% isA high power double-clad ytterbium-doped large-mode-area photonic crystal fiber (LMA PCF) laser was demonstrated using a unique Fabry-Perot (F-P) configuration. The pump source is a fiber coupled diode array operating at 976 nm. A continuous wave (CW) output power of 50 W at ~1.04 μm with a slope efficiency of 76.3% is obtained. Single transverse mode operation is achieved without any thermal-optical problems. This laser has the potential for scaling to much higher output power..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08457 (2005)
Multiwavelength Raman fiber ring laser with the spectrum profile broadened by parametric four wave mixing in highly nonlinear dispersion-shifted fibers
Yan Wang, Qing Wang, Wei Zhang, Xiaoming Liu, and Jiangde Peng
A broadband multiwavelength Raman fiber ring laser (RFRL) covering the whole C-band at room temperature are presented. The effect of the intracavity highly nonlinear dispersion-shifted fiber on broadening and flattening the output spectrum envelope is discussed and experimentally demonstrated. More than 45-dB extinctioA broadband multiwavelength Raman fiber ring laser (RFRL) covering the whole C-band at room temperature are presented. The effect of the intracavity highly nonlinear dispersion-shifted fiber on broadening and flattening the output spectrum envelope is discussed and experimentally demonstrated. More than 45-dB extinction-ratio multiwavelength output from 1527.76 to 1566.86 nm with 100-GHz channel spacing and 2.1-dB power ripple has been achieved by carefully controlling the individual powers of three pump lasers..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08460 (2005)
Diode-pumped single frequency Tm,Ho:YLF laser at room temperature
Xinlu Zhang, Youlun Ju, and Yuezhu Wang
A diode-pumped single frequency Tm,Ho:YLF laser operating at an eye-safe wavelength of 2 μm has been developed. Temperature of the laser crystal was controlled at room temperature with a thermoelectric cooler. The line-width narrowing elements were two solid uncoated fused silica etalons whose thicknesses were 1 and 0.A diode-pumped single frequency Tm,Ho:YLF laser operating at an eye-safe wavelength of 2 μm has been developed. Temperature of the laser crystal was controlled at room temperature with a thermoelectric cooler. The line-width narrowing elements were two solid uncoated fused silica etalons whose thicknesses were 1 and 0.1 mm, respectively. Continuous wave single frequency power of 113 mW was obtained..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08463 (2005)
1.3-μm uncooled 10 Gb/s directly modulated MQW AlGaInAs/InP laser diodes
Dingli Wang, Ning Zhou, Jun Zhang, Yu Liu, Ninghua Zhu, and Linsong Li
In this paper, we report a novel 1.3-μm uncooled AlGaInAs/InP multiple quantum well (MQW) ridge waveguide laser diodes. By optimizing the design of MQW structure and facet coatings, together with the application of reversed-mesa ridge waveguide (RM-RWG) structure, polyimide planarization, and lift-off processes technolIn this paper, we report a novel 1.3-μm uncooled AlGaInAs/InP multiple quantum well (MQW) ridge waveguide laser diodes. By optimizing the design of MQW structure and facet coatings, together with the application of reversed-mesa ridge waveguide (RM-RWG) structure, polyimide planarization, and lift-off processes technology, an uncooled 1.3-μm, 10-Gb/s directly modulated MQW ridge waveguide laser diode was successfully fabricated. The threshold current and the slope efficiency were 7 mA and 0.48 mW/mA, respectively. The directly modulated bandwidths of 11 and 9.2 GHz were achieved at room temperature and 80 Celsius degrees, respectively..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08466 (2005)
Materials
Characterization of Er^(3+)-doped Na2O-WO3-TeO2 glass for ion-exchanged waveguide amplifiers and lasers
Baoyu Chen, Shilong Zhao, Lili Hu, and Zhonghong Jiang
Er^(3+)-doped Na2O-WO3-TeO2 glass consistent with standard ion-exchange technology has been fabricated and characterized. The measured absorption and emission spectra of the glass were analyzed by the Judd-Ofelt and McCumber theories. The intensity parameters are Ω2 = 7.01*10^(-20) cm2, Ω4 = 1.80*10^(-20) cm2, Ω6 = 1.0Er^(3+)-doped Na2O-WO3-TeO2 glass consistent with standard ion-exchange technology has been fabricated and characterized. The measured absorption and emission spectra of the glass were analyzed by the Judd-Ofelt and McCumber theories. The intensity parameters are Ω2 = 7.01*10^(-20) cm2, Ω4 = 1.80*10^(-20) cm2, Ω6 = 1.03*10^(-20) cm2. The maximum emission cross-section is 0.91*10^(-20) cm2 at 1.533 μm, and a broad 1.5-μm emission spectrum of 65-nm full width at half-maximum (FWHM) is demonstrated. Glass transition temperature, crystallization onset temperature, density, refractive index are also reported for reference in the design and modelling of the ion-exchange process..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08472 (2005)
Nonlinear Optics
Generation of broadband and multiple-peak THz radiation in aperiodically poled lithium niobate
Fucheng Chen, Xianfeng Chen, Yuping Chen, and Yuxing Xia
We theoretically analyze the generation of broadened and multi-peak terahertz (THz) radiation in aperiodically poled lithium niobate (APPLN), whose sequence of opposite domains is optimized by simulated annealing (SA) algorithm. The full-width at half maximum (FWHM) of the broadened THz radiation in our simulation is 0We theoretically analyze the generation of broadened and multi-peak terahertz (THz) radiation in aperiodically poled lithium niobate (APPLN), whose sequence of opposite domains is optimized by simulated annealing (SA) algorithm. The full-width at half maximum (FWHM) of the broadened THz radiation in our simulation is 0.26 THz. Both of the central wavelength and FWHM can be easily tuned by choosing proper objective functions. THz radiation with wider and flatter FWHM can be achieved by increasing the length of the lithium niobate crystal. The two-peak THz generation is also provided as an example of multi-peak with the central wavelengths at 1.68 and 1.80 THz, respectively..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08475 (2005)
Optical Devices
High photoluminescence efficiency in polymer containing rare earth
Zhefu Wu, Qidan Ling, Xugang Shi, Jiangxin Zhang, and Guangxin Zhu
Three novel kinds of polymers containing rare earth europium have been synthesized and the integrating sphere technique was employed to measure the absolute photoluminescence (PL) efficiency. The PL efficiencies were found to be up to about 40%, which indicates the potential usage in organic light emitting devices (OLEThree novel kinds of polymers containing rare earth europium have been synthesized and the integrating sphere technique was employed to measure the absolute photoluminescence (PL) efficiency. The PL efficiencies were found to be up to about 40%, which indicates the potential usage in organic light emitting devices (OLED). The energy transfer from ligand to Eu ions and the 5D0 -> 7F2 transition of Eu^(3+) were analyzed under the PL process..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08480 (2005)
Optoelectronics
Rapid evaluation of gain spectra from measured ASE spectra of travelling-wave semiconductor optical amplifier
Qingyuan Miao, Dexiu Huang, Deming Liu, Tao Wang, and Xiaofei Zeng
An analytical equation, which directly relates amplified spontaneous emission (ASE) with small signal gain (SSG) of travelling-wave semiconductor optical amplifier (TWA), was derived. It was shown by theoretical analysis and experimental results that calibrated ASE spectra of TWA at different injection currents could bAn analytical equation, which directly relates amplified spontaneous emission (ASE) with small signal gain (SSG) of travelling-wave semiconductor optical amplifier (TWA), was derived. It was shown by theoretical analysis and experimental results that calibrated ASE spectra of TWA at different injection currents could be good evaluation and extension of SSG near gain peaks when gain peaks are larger than several decibels. The rapid evaluation method of SSG spectra is very simple, effective and especially applicable to batch measurement..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08483 (2005)
Thin Films
Effect of oxygen flow rate on the properties of SiOx films deposited by reactive magnetron sputtering
Fachun Lai, Ming Li, Haiqian Wang, Yousong Jiang, and Yizhou Song
SiOx (x=0--2) films were deposited on BK-7 substrates by a low frequency reactive magnetron sputtering system with the oxygen flow rate (OFR) changing from 0 to 30 sccm. The samples were characterized by atomic force microscopy, spectrophotometer, and X-ray photoelectron spectroscopy. The extinction coefficient and refSiOx (x=0--2) films were deposited on BK-7 substrates by a low frequency reactive magnetron sputtering system with the oxygen flow rate (OFR) changing from 0 to 30 sccm. The samples were characterized by atomic force microscopy, spectrophotometer, and X-ray photoelectron spectroscopy. The extinction coefficient and refractive index decrease, while the optical transmittance increases with the increase of OFR from 0 to 17 sccm. The root mean square surface roughness has a maximum at 10 sccm OFR. The highest deposition rate is at 15 sccm OFR. Our results show that the films deposited at 20 sccm OFR are stoichiometric silica with relatively high deposition rate, low extinction coefficient, and low surface roughness. Therefore, a precise control of OFR is very important to obtain high quality films for optical applications..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08490 (2005)
Deposition of ZnO thin films on (100) γ-LiAlO2 substrate
Jun Zou, Shengming Zhou, Xia Zhang, Fenglian Su, Xiaomin Li, and Jun Xu
Optical properties for ZnO thin films grown on (100) γ-LiAlO2 (LAO) substrate by pulsed laser deposition method were investigated. The c-axis oriented ZnO films were grown on (100) γ-LiAlO2 substrates at the substrate temperature of 550 Celsius degrees. The transmittance of the films was over 85%. Peaks attributed to eOptical properties for ZnO thin films grown on (100) γ-LiAlO2 (LAO) substrate by pulsed laser deposition method were investigated. The c-axis oriented ZnO films were grown on (100) γ-LiAlO2 substrates at the substrate temperature of 550 Celsius degrees. The transmittance of the films was over 85%. Peaks attributed to excitons were shown in absorption spectra, which indicated that thin films had high crystallinity. Photoluminescence spectra with the maximum peak at 540 nm were observed at room temperature, which seemed to be ascribed to oxygen vacancy in the ZnO films caused by diffusion of Li from the substrates into the films during the deposition..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08494 (2005)
Quantum Optics
Experimental observation of the linewidth narrowing of electromagnetically induced transparency resonance
Bo Wang, Shujing Li, Jingqin Yao, Jie Ma, Feng Peng, Gang Jiang, and Hai Wang
We report an experimental observation of the variation in linewidth of the electromagnetically induced transparency (EIT) resonance in a three-level Λ-type system for several laser bandwidths in a Rb vapor cell, with and without a buffer gas. It is found, using narrow bandwidth (about 20 kHz) diode laser for both couplWe report an experimental observation of the variation in linewidth of the electromagnetically induced transparency (EIT) resonance in a three-level Λ-type system for several laser bandwidths in a Rb vapor cell, with and without a buffer gas. It is found, using narrow bandwidth (about 20 kHz) diode laser for both coupling and probe beams, that the linewidth of the EIT resonance can be significantly narrowed in the Rb vapor cell with the buffer gas. The results are in good qualitative agreement with a simple theoretical calculation..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08486 (2005)
Atomic and Molecular Physics
Coherent population transfer with chirped few-cycle laser pulses in an excited-doublet four-level system
Weifeng Yang, Shangqing Gong, Yueping Niu, and Zhizhan Xu
The behavior of population transfer in an excited-doublet four-level system driven by linear polarized few-cycle ultrashort laser pulses is investigated numerically. It is shown that almost complete population transfer can be achieved even when the adiabatic criterion is not fulfilled. Moreover, the robustness of this The behavior of population transfer in an excited-doublet four-level system driven by linear polarized few-cycle ultrashort laser pulses is investigated numerically. It is shown that almost complete population transfer can be achieved even when the adiabatic criterion is not fulfilled. Moreover, the robustness of this scheme in terms of the Rabi frequencies and chirp rates of the pulses is explored..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08435 (2005)
A new semi-empirical formula for total cross sections of electron scattering from triatomic molecules at 30---5000 eV
Deheng Shi, Yufang Liu, Jinfeng Sun, and Zunlue Zhu
Total cross sections (TCSs) of electrons scattering from triatomic molecules over the energy range from 30 to 5000 eV are investigated employing a new semi-empirical formula. The TCSs of electrons scattering from triatomic molecules SO2, NO2, and CO2 are calculated. The quantitative TCSs are in good agreement with thosTotal cross sections (TCSs) of electrons scattering from triatomic molecules over the energy range from 30 to 5000 eV are investigated employing a new semi-empirical formula. The TCSs of electrons scattering from triatomic molecules SO2, NO2, and CO2 are calculated. The quantitative TCSs are in good agreement with those obtained by experiments. It is shown that the results derived from the semi-empirical formula are much closer to the measurements than other calculations..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08438 (2005)
Materials
Effect of nanocrystals on up-conversion luminescence of Er^(3+),Yb^(3+) co-doped glass-ceramics
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Different up-conversion luminescent spectra of Er^(3+) ions were observed in the oxyfluoride glass-ceramics. The ratio of two fluorides in the original compositions was modified in order to form different nanocrystals. The intensity of up-conversion luminescence increased sharply when the ratio of PbF2 and CdF2 was 40:Different up-conversion luminescent spectra of Er^(3+) ions were observed in the oxyfluoride glass-ceramics. The ratio of two fluorides in the original compositions was modified in order to form different nanocrystals. The intensity of up-conversion luminescence increased sharply when the ratio of PbF2 and CdF2 was 40:10. The data of differential thermal analysis and X-ray diffraction were used to explain the optimization fluoride ratio. The intensity of up-conversion luminescence is not only decided by the crystallizability but also mainly related with the stoichiometric proportion of fluoride nanocrystals in the glass-ceramics..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 469 (2005)
Optical Computing
Implementation of tristate logic based all optical flip-flop with nonlinear material
Partha Ghosh, and Sourangshu Mukhopadhyay
The advantages of multivalued logic in optical parallel computation need no introduction. There are lots of proposals, already reported, where tristate, quarternary state logic operations can be performed with optics. Here we report a new approach to implement tristate logic based all optical flip-flop using optical noThe advantages of multivalued logic in optical parallel computation need no introduction. There are lots of proposals, already reported, where tristate, quarternary state logic operations can be performed with optics. Here we report a new approach to implement tristate logic based all optical flip-flop using optical nonlinear material. The concept and the principle of operation of this type of flip-flop are different from that of the conventional binary one..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 8, 08478 (2005)
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