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Phase pre-emphasis for PAPR reduction in optical OFDM systems based on OIDFT or time lens

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Chinese Optics Letters 2010年第9期8卷 875-880页

作者：邵晶李蔚梁晓军 Wuhan National Lab for Optoelectronics Huazhong University of Science and Technology

Phase pre-emphasis is theoretically studied and introduced to reduce peak-to-average power ratio （PAPR） in optical orthogonal frequency division multiplexing （OFDM） systems. In intensity modulated （IM） systems, simulations show noticeable PAPR reductions： 4.14 dB （N = 16） and 15.48 dB （N = 512） in time lens-based OFDM, N is the number of subcarriers. An equation is developed to calculate phase values and is proved to be effective. optical implementing methods are proposed and analyzed. In a time lens-based OFDM system, phase pre-emphasis reduces fiber nonlinearity and results in a 5.2-dB increase of launch power at the bit error rate （BER） of 10 ？6 . Simulations also show similar PAPR reduction and fiber nonlinearity mitigation in optical inverse discrete Fourier transformer （OIDFT） based OFDM systems.

关键词： Bit error rate Frequency allocation Lenses optical instruments Orthogonal functions Telecommunication systems

Suppressing the disturbance in the transmission spectrum of Glan-Thompson-type prism polarizers

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Chinese Optics Letters 2010年第4期8卷 428-430页

作者：李红霞范吉阳苏富芳吴福全祝世宁 Department of Applied Physics Nanjing University of Science and Technology Department of Physics Nanjing University Department of Physics Southeast University Laser Research Institute Qufu Normal University Department of Physics Nanjing University

We analyze the random disturbance in the transmission of light through a spinning Glan-Thompsontype prism *** disturbance makes the dependence of the transmission on the rotation angle significantly deviates from the Malus cosine-squared law and severely spoils the output light *** vibration of the polarizer as it rotates combing the multi-beam-interference effect raises the disturbance. Further analysis reveals the sensitive dependence of the disturbance on the composing material of the prism gap,and the appropriate selection of such material can make the disturbance minimize to very desirable *** model results show quite good agreement with experiments.

关键词： Light sources optical instruments Prisms

A full resolution autostereoscopic 3D display based on polarizer parallax barrier

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Chinese Optics Letters 2010年第1期8卷 22-23页

作者：王琼华陶宇虹赵悟翔李大海 School of Electronics and Information Engineering Key Laboratory of Fundamental Synthetic Vision Graphics and Image for National DefenseSichuan University

A full resolution autostereoscopic three-dimensional （3D） display prototype is developed. It is composed of a time division thin film transistor liquid crystal display panel with an optical controlled birefringence liquid crystal polarization switch and a polarizer parallax barrier. Fast driving circuits operating at 120-Hz frame rate are fabricated. The 3D images on the display have the same resolution as the corresponding two-dimensional images, which is significantly different from conventional parallax barrier autostereoscopic 3D displays having degraded 3D image resolution.

关键词： Astrophysics Geometrical optics Image resolution Liquid crystal displays Liquid crystals optical instruments Thin film transistors

Design and analysis of flexible colorless remote node using RSOA-assisted Michelson interferometer

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Chinese Optics Letters 2011年第2期9卷 23-26页

作者：刘磊张民刘明涛张小频叶培大 Key Laboratory of Information Photonics and optical Communications Ministry of EducationBeijing University of Posts and Telecommunications

A scheme of flexible colorless remote note with reflective semiconductor optical amplifier （RSOA） assisted Michelson interferometer is proposed. This is capable of generating an optical carrier suppressed signal at a specific radio frequency to suppress the penalty brought about by Rayleigh backscattering and reflection in a full-duplex single fiber transmission network. Simulations are conducted, and the validation of the proposal is discussed by observing the penalty eye opening factor. The results are useful for designing cost-effective multi-wavelength passive optical network （PON） or radio-over-fiber （RoF） systems.

关键词： Fiber optic networks Michelson interferometers optical instruments Radio broadcasting Radio transmission Semiconductor optical amplifiers

Pseudo working-point control measurement scheme for acoustic sensitivity of interferometric fiber-optic hydrophones

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Chinese Optics Letters 2008年第5期6卷 381-383页

作者：王泽锋胡永明孟洲倪明 College of Photoelectric Science and Engineering National University of Defense Technology

A novel pseudo working-point control measurement scheme for the acoustic sensitivity of interferometric fiber-optic hydrophones is described and demonstrated. The measurement principle is introduced in detail. An experimental system, which interrogates an interferometric fiber-optic hydrophone with this method, is designed. The acoustic pressure phase sensitivity of the fiber-optic hydrophone is measured over the frequency range of 20- 2500 Hz. The measured acoustic sensitivity is about -156.5 dB re 1 rad/μPa with a fluctuation lower than ±1.2 dB, which is in good agreement with the results obtained by the method of phase generated carrier. The experimental results testify the validity of this new method which has the advantages of no electric elements in the sensing head, the simplicity of signal processing, and wide working bandwidth.

关键词： Acoustics Computer networks Electroacoustic transducers Fiber optics Interferometers Interferometry optical instruments Signal processing

Design of object surveillance system based on enhanced fish-eye lens

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Chinese Optics Letters 2009年第2期7卷 142-145页

作者：吴健辉杨坤涛项巧莲张南洋 College of Optoelectronic Science and Engineering Huazhong University of Science and Technology

A new method is proposed for the object surveillance system based on the enhanced fish-eye lens and the high speed digital signal processor （DSP）. The improved fish-eye lens images an ellipse picture on the charge-coupled device （CCD） surface, which increases both the utilization rate of the 4：3 rectangular CCD and the imaging resolution, and remains the view angle of 183° The algorithm of auto-adapted renewal background subtraction （ARBS） is also explored to extract the object from the monitoring image. The experimental result shows that the ARBS algorithm has high anti-jamming ability and high resolution, leading to excellent object detecting ability from the enhanced elliptical fish-eye image under varies environments. This system has potential applications in different security monitoring fields due to its wide monitoring space, simple structure, working stability, and reliability.

关键词： Charge coupled devices Digital cameras Digital signal processors Fish Lenses Meats optical instruments Security systems Signal processing

Theoretical analysis on two-photon absorption spectroscopy in a confined four-level atomic system

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Chinese Optics Letters 2009年第7期7卷 640-642页

作者：李院院白晋涛李莉张彦鹏侯洵 Institute of Photonics and Photonic Technology Key Laboratory of Photoelectronic Technology of Sha~nxi Province Northwest University Xi'an 710069 China Department of Physics Xi'an University of Arts and Science Xi'an 710065 China Key Laboratory for Physical Electronics and Devices of the Ministry of Education Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory of Transient Optics and Technology Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an 710068 China

We investigate theoretically two-photon absorption spectroscopy modified by a control field in a confined Y-type four-level system. Dicke-narrowing effect occurs both in two-photon absorption lines and the dips of transparency against two-photon absorption due to enhanced contribution of slow atoms. We also find that the suppression and the enhancement of two-photon absorption can be modified by changing the strength of the control field and the detuning of three laser fields. This control of two-photon absorption may have some applications in information processing and optical devices.

关键词： Absorption Atomic spectroscopy Data processing Light absorption Luminescence of organic solids Multiphoton processes optical instruments optical materials Photons

Preparation of high performance thin-film polarizers

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Chinese Optics Letters 2010年第6期8卷 624-626页

作者：朱美萍易葵张伟丽范正修贺洪波邵建达 Key Laboratory of High Power Laser Materials Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Graduate University of Chinese Academy of Sciences

The optical performance of thin film polarizers is highly sensitive to the layer thicknesses of thin *** thicknesses of the sensitive layers are optimized in order to gain broader polarizing zone in such case when the total layer thickness does not *** automatic layer thickness control system is established,and errors caused by different monitoring methods are *** this thickness control system,thin-film polarizers with Tp higher than 98%and Tp/Ts higher than 200：1（Tp and Ts are transmissions for p- and s-polarizations,respectively） with the bandwidth of 11 nm are *** the system allows for optimum repeatability of three successive runs.

关键词： Control systems optical instruments Thickness control Thin films

Deep silicon grating as high-extinction-ratio polarizing beam splitter

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Chinese Optics Letters 2009年第4期7卷 325-328页

作者：冯吉军周常河王博郑将军 Information Optics Lab Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

A deep binary silicon grating as high-extinction-ratio reflective polarizing beam splitter （PBS） at the wavelength of 1550 nm is presented. The design is based on the phenomenon of total internal reflection （TIR） by using the rigorous coupled wave analysis （RCWA）. The extinction ratio of the rectangular PBS grating can reach 2.5~105 with the optimum grating period of 397 nm and groove depth of 1.092 μm. The efficiencies of TM-polarized wave in the 0th order and TE-polarized wave in the -1st order can both reach unity at the Littrow angle. Holographic recording technology and inductively coupled plasma （ICP） etching could be used to fabricate the silicon PBS grating.

关键词： Inductively coupled plasma optical instruments Particle beams Prisms Refractive index