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Bio-inspired optimization algorithms for optical parameter extraction of dielectric materials: A comparative study

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Chinese Physics B 2016年第10期25卷 202-208页

作者： Md Ghulam Saber Kh Arif Shahriar Ashik Ahmed Rakibul Hasan Sagor department of Electrical and electronic engineering Islamic University of Technology (IUT) department of Electrical and electronic engineering Northern University Bangladesh (NUB)

Particle swarm optimization(PSO) and invasive weed optimization(IWO) algorithms are used for extracting the modeling parameters of materials useful for optics and photonics research community. These two bio-inspired algorithms are used here for the first time in this particular field to the best of our knowledge. The algorithms are used for modeling graphene oxide and the performances of the two are compared. Two objective functions are used for different boundary values. Root mean square(RMS) deviation is determined and compared.

关键词： optical parameter extraction particle swarm optimization invasive weed optimization graphene oxide optimization

Highly efficient cascaded P-doped Raman fiber laser pumped by Nd:YVO4 solid-state laser

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Chinese Optics Letters 2008年第1期6卷 41-43页

作者：黄朝红蔡志平罗正钱黄文财许惠英叶陈春 department of electronic engineering Xiamen University

A highly efficient cascaded P-doped Raman fiber laser （RFL） pumped by a 1064-nm continuous wave （CW） Nd：YVO4 solid-state laser is reported. 1.15-W CW output power at 1484 nm is obtained while the input pump power is 4 W, corresponding to the power conversion efficiency of 28.8%. The threshold pump power for the second-order Stokes radiation is 1.13 W. The slope efficiency is as high as 42.6%. The experimental results are in good agreement with theoretical ones. Furthermore, the power instability of the P-doped RFL at 1484 nm in an hour is observed to be less than 5%.

关键词： Continuous wave lasers Conversion efficiency Fiber lasers Optically pumped lasers

Demonstration of a 16×10-Gb/s OTDM system

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Chinese Optics Letters 2007年第5期5卷 264-266页

作者：杨彦甫娄采云高以智 department of electronic engineering Tsinghua University

A 16×10-Gb/s optical time-division-multiplexing （OTDM） system was demonstrated experimentally with a well-designed ultrashort pulse source based on an electro-absorption modulator （EAM） and nonlinear fiber compressor. The obtained 10-GHz stable and pedestal-free pulse train has 2-ps width, high extinction ratio, and low timing jitter. An ultrafast demultiplexer based on a nonlinear optical loop mirror （NOLM） including a commercially available highly nonlinear fiber （HNLF） is employed to demultiplex data signal from 160 to 10 Gb/s. A back-to-back error-free demultiplexing experiment is carried out to verify the system performance.

关键词： Compressors Mirrors Modulators Optical fibers Timing jitter Ultrashort pulses

Novel discretely tunable narrow linewidth fiber laser with uniform wavelength spacing

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Chinese Optics Letters 2007年第4期5卷 218-220页

作者：董小鹏陈勇 department of electronic engineering Xiamen University

A novel configuration of the tunable fiber laser with uniform wavelength spacing in dense wavelength division multiplexing （DWDM） application is proposed. The ring type tunable fiber laser consists of an all-fiber comb filter which determines the wavelength spacing, and a piece of adjustable fiber grating to select the discrete lasing wavelength for DWDM application. The proposed all-fiber ring type tunable laser has potential application in the DWDM and other optical systems due to its advantages such as narrow linewidth, easv tuning, uniform wavelength interval, etc..

关键词： Dense wavelength division multiplexing Diffraction gratings Linewidth Optical systems

Frequency locking,quasiperiodicity,and chaos in dual-frequency loss-modulated erbium-doped fiber lasers

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Chinese Optics Letters 2009年第8期7卷 699-702页

作者：刘越张巍冯雪刘小明 department of electronic engineering Tsinghua University

Dynamic behaviors of the erbium-doped fiber laser （EDFL） with dual-frequency loss modulation are experimentally investigated. Frequency-locked states with their winding numbers which form the devil＇s staircase are observed in this kind of lasers. In the unlocked regions, the output state changes from quasiperiodicity to chaos under increasing modulation index, which demonstrates a different route to chaos from the conventional loss-modulated EDFLs with a single modulation frequency. The chaos output in the dual-frequency loss-modulated EDFLs shows less harmonic components of the modulation frequency in the corresponding power spectrum, indicating the improvement of the randomness of the chaotic signals.

关键词： Chaos theory Erbium Modulation Power spectrum Ring lasers

Structural and electrical characteristics of lanthanum oxide gate dielectric film on GaAs pHEMT technology

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Journal of Semiconductors 2009年第11期30卷 43-46页

作者：吴家松刘兴中 department of electronic engineering Vanung University

This paper investigates the feasibility of using a lanthanum oxide thin film （La2O3） with a high dielectric constant as a gate dielectric on GaAs pHEMTs to reduce gate leakage current and improve the gate to drain breakdown voltage relative to the conventional GaAs pHEMT. An E/D mode pHEMT in a single chip was realized by selecting the appropriate La2O3 thickness. The thin La2O3 film was characterized： its chemical composition and crystalline structure were determined by X-ray photoelectron spectroscopy and X-ray diffraction, respectively. La2O3 exhibited good thermal stability after post-deposition annealing at 200, 400 and 600℃ because of its high binding-energy （835.6 eV）. Experimental results clearly demonstrated that the La2O3 thin film was thermally stable. The DC and RF characteristics of Pt/La2O3/Ti/Au gate and conventional Pt/Ti/Au gate pHEMTs were examined. The measurements indicated that the transistor with the Pt/La2O3/Ti/Au gate had a higher breakdown voltage and lower gate leakage current. Accordingly, the La2O3 thin film is a potential high-k material for use as a gate dielectric to improve electrical performance and the thermal effect in high-power applications.

关键词： lanthanum oxide XR XPS oHEMTs

Methods of Data Processing for Trace Elements Analysis Using Laser Induced Breakdown Spectroscopy

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Plasma Science and Technology 2015年第11期17卷 944-947页

作者：王锐马晓红余琦宋阳赵华凤张敏廖延彪 electronic engineering department Tsinghua University

With the development of Laser Induced Breakdown Spectroscopy （LIBS）, increasing numbers of researchers have begun to focus on problems of the application. We are not just satisfied with analyzing what kinds of elements are in the samples but are also eager to accomplish quantitative detection with LIBS. There are several means to improve the limit of detection and stability, which are important to quantitative detection, especially of trace elements, increasing the laser energy and the resolution of spectrometer, using dual pulse setup, vacuuming the ablation environment etc. All of these methods are about to update the hardware system, which is effective but expensive. So we establish the following spectrum data processing methods to improve the trace elements analysis in this paper： spectrum sifting, noise filtering, and peak fitting. There are small algorithms in these three method groups, which we will introduce in detail. Finally, we discuss how these methods affect the results of trace elements detection in an experiment to analyze the lead content in Chinese cabbage.

关键词： LIBS data processing limit of detection spectrum sift noise filtering peak fitting

Function-lock strategy in OR/NOR optical logic gates based on cross-polarization modulation effect in semiconductor optical amplifier

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Chinese Optics Letters 2007年第10期5卷 566-568页

作者：扬晶生韩柳燕张汉一郭奕理 department of electronic engineering Tsinghua University

We have studied a function-lock strategy for all-optical logic gate （AOLG） utilizing the cross-polarization modulation （CPM） effect in a semiconductor optical amplifier （SOA）. By monitoring the power of logic light, the strategy realized controllable methods to capture OR and NOR functions and switch between them. The strategy has been successfully applied in experiment with 10-Gb/s not-return-to-zero （NRZ） signals, which has a high success-rate above 95% and ensures the high extinction ratio of result light above 11.4 dB. Every step in the strategy has definite numeric evaluation, which provides the potential of automatic implementation.

关键词： Boolean algebra Logic gates Signal encoding

Characterization and Performance Evaluation of Turbulent Plasma Sheath Channel

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China Communications 2016年第6期13卷 88-99页

作者： Jingzhuo Zhang Guolong He Peng Bai Jianhua Lu Ning Ge department of electronic engineering Tsinghua University Synthetic electronic Information System and electronic Countermeasure Technology Research department Air Force Engineering University

Radio waves are highly attenuated and distorted by turbulent plasma sheath around hypersonic vehicles in near space, leading to communication blackout. The purpose of the paper is to investigate the plasma channel characteristics and the communication performances over the channel. We treat the turbulent plasma medium as a fast fading wireless channel. The coherence time and the spectrum spread of the plasma sheath channel are obtained in terms of root-meansquare(RMS). Baseband simulation scheme is proposed based on a stratified model of the plasma flow field. Results indicate that the coherence time is on the order of milliseconds and decreases rapidly with the increasing electron density turbulence. The spectrum spread due to plasma turbulence is also significant. Extensive simulations have been carried out to make communication performance evaluations. Quantitative results show that error floor takes place for PSK and QAM, while FSK with noncoherent detection is a promising method to mitigate the blackout problem.

关键词： plasma sheath channel characteristics fast fading error performance