Journals >Chinese Optics Letters
Contents
2005
Volume: 3 Issue 10
19 Article(s)
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Fiber Optics and Optical Communications
Picosecond soliton transmission using concatenated gain-distributed nonlinear amplifying fiber loop mirrors
Wenhua Cao, and Songhao Liu
Stable picosecond soliton transmission is demonstrated numerically by use of concatenated gain-distributed nonlinear amplifying fiber loop mirrors (NALMs). We show that, as compared with previous soliton transmission schemes that use conventional NALMs or nonlinear optical loop mirror (NOLM) and amplifier combinations,Stable picosecond soliton transmission is demonstrated numerically by use of concatenated gain-distributed nonlinear amplifying fiber loop mirrors (NALMs). We show that, as compared with previous soliton transmission schemes that use conventional NALMs or nonlinear optical loop mirror (NOLM) and amplifier combinations, the present scheme permits significant increase of loop-mirror (amplifier) spacing. The broad switching window of the present device and the high quality pulses switched from it provide a reasonable stability range for soliton transmission. Soliton-soliton interactions can be reduced efficiently by using lowly dispersive fibers..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10562 (2005)
Analysis of dispersion compensation for position-dependence in externally modulated CATV lightwave systems by using chirped fiber grating
Qing Ye, Feng Liu, Haiwen Cai, Ronghui Qu, and Zujie Fang
The dispersion compensation characteristics of the chirped fiber grating (CFG) for different dispersion compensation positions are analyzed in externally modulated cable television (CATV) lightwave system and the analytic expression of the composite second order (CSO) distortion is derived. The analyses give a reasonabThe dispersion compensation characteristics of the chirped fiber grating (CFG) for different dispersion compensation positions are analyzed in externally modulated cable television (CATV) lightwave system and the analytic expression of the composite second order (CSO) distortion is derived. The analyses give a reasonable explanation for the position-dependent effect of CFG dispersion compensator, which was found in practical systems. Moreover, the theoretical result is also verified by an experiment. It is believed that the theory will be helpful in designing optical CATV fiber links with nodes at proper positions both for intensity amplification and dispersion compensation..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10566 (2005)
Low pump power co-fiber remotely pumped EDFA used in DWDM systems with ultra-long fiber span
Fan Zhang, Wei Zhang, Yan Wang, and Jiangde Peng
In this paper, aiming at practical dense wavelength division multiplexing (DWDM) system with ultra-long fiber span, a simple co-fiber remotely pumped erbium-doped fiber amplifier (RP-EDFA) scheme is proposed to extend span distance with simple configuration and low pump power. Equivalent noise figure of -6 dB is achievIn this paper, aiming at practical dense wavelength division multiplexing (DWDM) system with ultra-long fiber span, a simple co-fiber remotely pumped erbium-doped fiber amplifier (RP-EDFA) scheme is proposed to extend span distance with simple configuration and low pump power. Equivalent noise figure of -6 dB is achieved under 300-mW pump power. Using the experiment results, numerical simulation of ultra-long span systems shows that for a 40*11.6-Gb/s transmission system, the RP-EDFA scheme can support transmission of 1760 km with a fiber span of 160 km. These results demonstrate the potential of the PR-EDFA scheme in ultra-long span transmission..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10570 (2005)
Theoretical analysis and experimental verification of a cost-effective chromatic dispersion monitoring method in a 40-Gb/s optical fiber communication system
Yan Li, Jin Zhang, Jinlong Yu, Wencai Jing, Yimo Zhang, and Ge Zhou
A cost-effective technique for in-service chromatic dispersion monitoring in a 40-Gb/s optical communication system is proposed. Microwave devices are adopted to detect the electrical power of a specific frequency band. A simplified theoretical model is proposed and discussed focusing on the relationship between electrA cost-effective technique for in-service chromatic dispersion monitoring in a 40-Gb/s optical communication system is proposed. Microwave devices are adopted to detect the electrical power of a specific frequency band. A simplified theoretical model is proposed and discussed focusing on the relationship between electrical power and chromatic dispersion at different frequency bands. The dynamic monitoring of chromatic dispersion is achievedusing devices such as PIN detector, microwave amplifier, narrow-band microwave filter, and electrical power detector. The maximum detectable chromatic dispersion is 130 ps/nm and a resolution of 5.2 ps/nm/dB has been achieved in the frequency band centered at 12 GHz..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10573 (2005)
Technical study of visible light wavelength division multiplexing using polymer optical fiber
Yongsheng Zhang, Hui Ma, Tao Zhang, Zhuo Wang, Dong Wang, Rongsheng Zheng, Haipeng Yang, and Hai Ming
Visible light wavelength division multiplexing (VWDM) experiment was performed using polymer optical fiber (POF). Lights of two different wavelengths (650 and 530 nm) were sent to a single POF. Red light (650 nm) was used for 100-Mb/s full duplex IP data transmission and green light (530 nm) was used for voice signal tVisible light wavelength division multiplexing (VWDM) experiment was performed using polymer optical fiber (POF). Lights of two different wavelengths (650 and 530 nm) were sent to a single POF. Red light (650 nm) was used for 100-Mb/s full duplex IP data transmission and green light (530 nm) was used for voice signal transmission. Light sources are light-emitting diodes (LEDs). A POF coupler (splitter) and the prisms were employed as multiplexer and demultiplexer, respectively. The channel isolation and insert loss were measured, which are 20.5 and 17.65 dB for 650-nm channel respectively, and 19.16 and 20.55 dB for 530 nm one respectively..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10577 (2005)
Analytical formulas for calculating the blocking probability of a dynamic star network
Jiajia Chen, Xiang Lu, and Sailing He
For a dynamic routing and wavelength assignment (RWA) a star topology is shown to be more efficient in comparison with a ring topology. Analytical formulas for a dynamic RWA in a star network are presented and verified with virtual simulation.For a dynamic routing and wavelength assignment (RWA) a star topology is shown to be more efficient in comparison with a ring topology. Analytical formulas for a dynamic RWA in a star network are presented and verified with virtual simulation..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10579 (2005)
Image Processing
Error detection using mode information of macroblocks for video transmission
Yong Fang, Chengke Wu, and Hong Zhu
A new method for error detection using mode information of macroblocks (MBs) is proposed. For decodable inter MBs, inter residues are calculated by adding up absolute values of received residual pixels and intra complexities are estimated by that of motion compensated reference blocks. If inter residues are larger thanA new method for error detection using mode information of macroblocks (MBs) is proposed. For decodable inter MBs, inter residues are calculated by adding up absolute values of received residual pixels and intra complexities are estimated by that of motion compensated reference blocks. If inter residues are larger than intra complexities by a predefined quantity, MBs are considered to be erroneous. For decodable intra MBs, the connective smoothness of the current MB with correctly decoded neighboring MBs is tested to find erroneous MBs. Combined with error concealment, the new method improves the quality of reconstructed images by about 0.5-1 dB in peak signal-noise ratio (PSNR)..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10582 (2005)
CCD camera automatic calibration technology and ellipse recognition algorithm
Changku Sun, Xiaodong Zhang, and Yunxia Qu
A novel two-dimensional (2D) pattern used in camera calibration is presented. With one feature circle located at the center, an array of circles is photo-etched on this pattern. An ellipse recognition algorithm is proposed to implement the acquisition of interest calibration points without human intervention. AccordingA novel two-dimensional (2D) pattern used in camera calibration is presented. With one feature circle located at the center, an array of circles is photo-etched on this pattern. An ellipse recognition algorithm is proposed to implement the acquisition of interest calibration points without human intervention. According to the circle arrangement of the pattern, the relation between three-dimensional (3D) and 2D coordinates of these points can be established automatically and accurately. These calibration points are computed for intrinsic parameters calibration of charge-coupled device (CCD) camera with Tsai method. A series of experiments have shown that the algorithm is robust and reliable with the calibration error less than 0.4 pixel. This new calibration pattern and ellipse recognition algorithm can be widely used in computer vision..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10585 (2005)
Imaging Systems
A novel method to determine the FOCAL energy range
Dongqing Zhang, Xiangzhao Wang, and Weijie Shi
Determination of the energy range is an important precondition of focus calibration using alignment procedure (FOCAL) test. A new method to determine the energy range of FOCAL off-lined is presented in this paper. Independent of the lithographic tool, the method is time-saving and effective. The influences of some procDetermination of the energy range is an important precondition of focus calibration using alignment procedure (FOCAL) test. A new method to determine the energy range of FOCAL off-lined is presented in this paper. Independent of the lithographic tool, the method is time-saving and effective. The influences of some process factors, e.g. resist thickness, post exposure bake (PEB) temperature, PEB time and development time, on the energy range of FOCAL are analyzed..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10589 (2005)
Lasers and Laser Optics
Efficient stable simultaneous CW dual-wavelength diode-end-pumped Nd:YAG laser operating at 1.319 and 1.338 μm
Rui Zhou, Wuqi Wen, Zhiqiang Cai, Xin Ding, Peng Wang, and Jianquan Yao
An efficient, stable diode-end-pumped simultaneous continuous-wave (CW) dual-wavelength laser operating at 1.319 and 1.338 μm in a Nd:YAG crystal has been demonstrated. A total output power of 6.3 W is achieved at an absorbed pump power of 15 W, with a slope efficiency of 43.5%. The instability of output power is less An efficient, stable diode-end-pumped simultaneous continuous-wave (CW) dual-wavelength laser operating at 1.319 and 1.338 μm in a Nd:YAG crystal has been demonstrated. A total output power of 6.3 W is achieved at an absorbed pump power of 15 W, with a slope efficiency of 43.5%. The instability of output power is less than 1%. With a type II critical phase-matched KTP crystal inserted into the cavity as frequency doubler, a maximum outputpower of 200 mW in red region is acquired. In addition, a six-wavelength laser operation at 1.319 μm, 1.338 μm, 1.356 μm, 659.5 nm, 669 nm, and 678 nm is observed..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10597 (2005)
Tunable fiber ring laser employing a Sagnac interferometric filter
Xiaofeng Jin, and Kejiang Zhou
A tunable erbium-doped fiber ring laser employing an all-polarization-maintaining fiber loop filter is proposed and demonstrated. The lasing frequencies can be selected by properly adjusting the polarization controller in the cavity.A tunable erbium-doped fiber ring laser employing an all-polarization-maintaining fiber loop filter is proposed and demonstrated. The lasing frequencies can be selected by properly adjusting the polarization controller in the cavity..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10600 (2005)
Thin Films
Determination of the effective refractive index of porous silicon/polymer composite films
Zhenhong Jia
The equation for calculating the effective refractive index of porous silicon inserted polymer was obtained by three-component Bruggeman effective medium model. The dependence of the effective refractive index of porous silicon/polymer composite films on the polymer fraction with various initial porosity was given theoThe equation for calculating the effective refractive index of porous silicon inserted polymer was obtained by three-component Bruggeman effective medium model. The dependence of the effective refractive index of porous silicon/polymer composite films on the polymer fraction with various initial porosity was given theorically and experimentally respectively. The porous silicon and polymer polymethylmetacrylate based dispersive red one (PMMA/DR1) composite films were fabricated in our experiments. It is found that the measured effective refractive index of porous silicon inserted polymer was slightly lower than the calculated result because of the oxidization of porous silicon. The effective refractive index of oxidized porous silicon inserted polymer also was analyzed by four-component medium system..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10608 (2005)
Third-order optical nonlinearities of Zn_(1-x)MgxO thin films
Naibo Chen, Huizhen Wu, Tianning Xu, Ping Yu, and Dongjiang Qiu
The Zn_(1-x)MgxO thin films were deposited on sapphire substrates by reactive electron beam evaporation deposition (REBED). The X-ray diffraction (XRD) measurement demonstrates that these films undergo phase transition from hexagonal to cubic with increasing the Mg concentration. Absorption coefficients at 532 nm of thThe Zn_(1-x)MgxO thin films were deposited on sapphire substrates by reactive electron beam evaporation deposition (REBED). The X-ray diffraction (XRD) measurement demonstrates that these films undergo phase transition from hexagonal to cubic with increasing the Mg concentration. Absorption coefficients at 532 nm of the samples were obtained from the absorption spectra. Using optical Kerr effect, the third-order susceptibilities of the ternary films over a wide range of Mg concentrations were determined. The magnitude of χ(3) of the ternary Zn_(1-x)MgxO films is order of 10^(-11) esu at λ = 532 nm. The sample with phase mixture of both hexagonal and cubic structures shows the largest third-order susceptibility. The difference observed in the magnitude of χ(3) of Zn_(1-x)MgxO films is attributed to the different microstructures of the ternary films, such as crystalline phase separation and crystal grains that enhance stimulated scattering..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10611 (2005)
Instrumentation, Measurement, and Metrology
Comparison of optical detection system, PVDF detection system, and PVDF needle hydrophone for optoacoustic tomography
M. D. Abolhassani, M. Hejazi, A. Ahmadian, and A. Amjadi
Optoacoustic tomography (PAT) is a two-dimensional medical imaging method that has the advantage of optical contrast and resolution of ultrasonic waves. The detection systems with a high sensitivity can be used for detecting small tumors, located deeply in human tissues, such as the breast. In this study, the sensitiviOptoacoustic tomography (PAT) is a two-dimensional medical imaging method that has the advantage of optical contrast and resolution of ultrasonic waves. The detection systems with a high sensitivity can be used for detecting small tumors, located deeply in human tissues, such as the breast. In this study, the sensitivity of existing ultrasonic detection systems has been compared experimentally with that by using thermoelastic waves as a broadband ultrasonic source. For the comparison, an optical stress transducer (OST), a polyvinylidene difluoride (PVDF) sheet and a calibrated PVDF needle hydrophone were used. To ensure all of the detection systems interrogated by the same ultrasonic field, a small optical instrument that fixed the generating laser head was constructed. The sensitivity was evaluated by measuring signal-to-noise ratios (SNRs) and noise equivalent pressures (NEPs). The PVDF system, with a 4-kPa NEP has a 22 dB better performance than the OST. The OST showed nearly the same sensitivity as the hydrophone for detecting ultrasound waves at a 1-cm distance in water. PVDF detection system provides a useful tool for imaging of soft tissues because of its high sensitivity and broad detection range..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10593 (2005)
Spectroscopy
Application of step-scan FTIR to the research of quantum cascade lasers
Junqi Liu, Xiuzhen Lu, Yu Guo, Xiuqi Huang, Xiaoling Che, Wen Lei, and Fengqi Liu
The principle of step-scan Fourier transform infrared (FTIR) spectroscopy is introduced. Double modulation step-scan FTIR technique is used to obtain the quantum cascade laser's stacked emission spectra in the time domain. Optical property and thermal accumulation of devices due to large drive current are analyzed.The principle of step-scan Fourier transform infrared (FTIR) spectroscopy is introduced. Double modulation step-scan FTIR technique is used to obtain the quantum cascade laser's stacked emission spectra in the time domain. Optical property and thermal accumulation of devices due to large drive current are analyzed..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10603 (2005)
Clustering study in Eu(DBM)3Phen-doped polymer optical fibers by optical properties and near-field scanning microscopy
Zhiqiang Zheng, Hai Ming, Xiaohong Sun, and Jianping Xie
The clusters of Eu^(3+) ion in Eu(DBM)3Phen-doped polymethyl methacrylate (PMMA) have been studied by three means. The relative fluorescence intensity ratio of the 5D0 -> 7F2 to 5D0 -> 7F1 transitions with different concentrations of Eu^(3+) in Eu(DBM)3Phen-doped PMMA and metastable-state (5D0) lifetime depThe clusters of Eu^(3+) ion in Eu(DBM)3Phen-doped polymethyl methacrylate (PMMA) have been studied by three means. The relative fluorescence intensity ratio of the 5D0 -> 7F2 to 5D0 -> 7F1 transitions with different concentrations of Eu^(3+) in Eu(DBM)3Phen-doped PMMA and metastable-state (5D0) lifetime dependence on Eu^(3+) concentration are analyzed. The analysis indicates that there are no clustering effects in Eu^(3+) ions of Eu(DBM)3Phen-doped PMMA when the Eu^(3+) doping concentration is up to 1.0 wt.-%. At the same time, the clustering effect has not been observed by the scanning near-field optical microscopy (SNOM) in Eu(DBM)3Phen-doped PMMA with 1.0 wt.-% of Eu^(3+) ions. The analysis reveals that a high concentration of Eu^(3+) can be incorporated into polymer optical fiber (POF) without clustering effect..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10605 (2005)
Ultrafast Optics
Ablation and ultrafast dynamics of zinc selenide under femtosecond laser irradiation
Xiaofeng Wang, Tianqing Jia, Xiaoxi Li, Chengbin Li, Donghai Feng, Haiyi Sun, Shizhen Xu, and Zhizhan Xu
The ablation in zinc selenide (ZnSe) crystal is studied by using 150-fs, 800-nm laser system. The images of the ablation pit measured by scanning electronic microscope (SEM) show no thermal stress and melting dynamics. The threshold fluence is measured to be 0.7 J/cm2. The ultrafast ablation dynamics is studied by usinThe ablation in zinc selenide (ZnSe) crystal is studied by using 150-fs, 800-nm laser system. The images of the ablation pit measured by scanning electronic microscope (SEM) show no thermal stress and melting dynamics. The threshold fluence is measured to be 0.7 J/cm2. The ultrafast ablation dynamics is studied by using pump and probe method. The result suggests that optical breakdown and ultrafast melting take place in ZnSe irradiated under femtosecond laser pulses..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10615 (2005)
X-Ray Optics
Application of the probability theory in predicting 3D focusing behaviors of compound X-ray refractive lenses
Zichun Le, Xinjian Zhao, Jingqiu Liang, Yaping Sun, Kai Liu, Ming Zhang, Shuqin Guo, and Bisheng Quan
A theoretical method based on the diffractive theory is used for predicting three-dimensional (3D) focusing performances of the compound X-rays refractive lenses (CRLs). However, the derivation of the 3D intensity distribution near focus for the X-ray refractive lenses is quite complicated. In this paper, we introduce A theoretical method based on the diffractive theory is used for predicting three-dimensional (3D) focusing performances of the compound X-rays refractive lenses (CRLs). However, the derivation of the 3D intensity distribution near focus for the X-ray refractive lenses is quite complicated. In this paper, we introduce a simple theoretical method that is based on the first and second moments in the theory of probability. As an example, the 3D focusing performance of a CRL with Si material is predicted. Moreover, the results are compared with those obtained by the diffractive theory. It is shown that the method introduced in this paper is accurate enough..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10618 (2005)
Atmospheric and Oceanic Optics
Partially coherent vortex beams propagation in a turbulent atmosphere
Yixin Zhang, Minxia Tang, and Chunkan Tao
Based on the Rytov approximation and the cross-spectral density approximation for the mutual coherence function of the partially coherent field, the propagation properties of the partially coherent beams with optical vortices in turbulent atmosphere are discussed. The average intensity and the mutual coherence functionBased on the Rytov approximation and the cross-spectral density approximation for the mutual coherence function of the partially coherent field, the propagation properties of the partially coherent beams with optical vortices in turbulent atmosphere are discussed. The average intensity and the mutual coherence function of the partially coherent vortex beams propagation in weak turbulent atmosphere are obtained. It is shown that the vortex structure of the average cross-spectral density of partially coherent beams has the same helicoidally shape as that of the phase of the fully coherent Laguerre-Gauss beams in free space and the relative intensity of the beam is degraded by optical vortex..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 10, 10559 (2005)
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