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To optimize splice joint between different PCF-based devices and SMF transmission medium

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Chinese Optics Letters 2009年第3期7卷 246-250页

作者： Faramarz E.Seraji S.Farsinezhad optical communication group Iran Telecom Research Center Electrical Engineering Department Semnan University

An analysis of splice loss between photonic crystal fibers （PCFs） and conventional single-mode fibers （SMFs） is presented at bending and straight conditions, by using scalar effective index method （SEIM）, vectorial effective index method （VEIM）, and finite-difference frequency domain （FDFD） methods. It is shown that when there is a slight bending at the vicinity of splice joint, the spot size increases sharply at higher frequencies. On the basis of the obtained results, a mechanism to optimize the splice loss between PCFs and conventional SMFs, both with any geometry, is suggested. The results can be utilized for PCF- based devices to be jointed to SMF as a transmission medium.

关键词： Frequency domain analysis Photonic crystal fibers

Characteristics of holey fibers fabricated at different drawing speeds

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Chinese Optics Letters 2007年第3期5卷 131-134页

作者： Faramarz E.Seraji Mahnaz Rashidi Maryam Karimi optical communication group iran Telecom research center Tehran Iran Physics group Guilan University RashtIran Physics group Razi University KermanshahIran

The effects of high drawing speeds on parameters of holey fibers are presented. A holey fiber preform structure was made by using tube-in-tube method and was drawn at high speeds with an aim of mass production to meet the demand of next generation communication systems. Transmission parameters such as numerical aperture and normalized frequency of the fabricated holey fibers have been measured and compared with theoretical values based on effective index method. Although the fabricated holey fibers were not of high quality, the analyses of the parameters have shown promising outlook for fabrication of such fibers.

关键词： Characteristics of holey fibers fabricated at different drawing speeds

Peak shrinking and interpolating for PAPR reduction in M-IFoF-based mobile fronthaul

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Digital communications and Networks 2022年第1期8卷 51-57页

作者： Luping Qin Haibo Li Da Chen Tao Jiang research center of 6G Mobile communications School of Cyber Science and Engineering Huazhong University of Science and Technology1037 Luoyu RoadWuhan 430074China State Key Laboratory of optical communication Technologies and Networks China Information Communication Technologies Group CorporationWuhan430074China

We apply a Peak Shrinking and Interpolating(PSI)scheme to improve the Peak-to-Average Power Ratio(PAPR)performance in Multiple Intermediate-Frequency-over-Fiber(M-IFoF)based mobile *** key idea is to detect the high peaks of the signal and shrink them,and then the shrunk peak values are interpolated into the original signal to reduce the *** also compare the PSI technique with the previous Tone-Reservation(TR)technique and Phase Pre-Distortion(PPD)technique in terms of PAPR reduction effect and computational *** simulation results indicate that the PSI scheme can reduce the PAPR by more than 4.3 dB at 0.1%CCDF,which outperforms the two previous schemes with lower computational ***,we find that altering M-IFoF system parameters has little effect on the performance of the PSI technique.

关键词： Mobile fronthaul Multi-IF-Over-Fiber(M-IFoF) Peak Shrinking and Interpolating(PSI) Tone-Reservation(TR) Phase Pre-Distortion(PPD)

High-speed and high-power germanium photodetector with a lateral silicon nitride waveguide

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Photonics research 2021年第5期9卷 749-756页

作者： XIAO HU DINGYI WU HONGGUANG ZHANG WEIZHONG LI DAIGAO CHEN LEI WANG XI XIAO SHAOHUA YU National Information Optoelectronics Innovation center China Information and Communication Technologies Group Corporation(CICT)Wuhan 430074China State Key Laboratory of optical communication Technologies and Networks China Information and Communication Technologies Group Corporation(CICT)Wuhan 430074China

Up to now, the light coupling schemes of germanium-on-silicon photodetectors(Ge-on-Si PDs) could be divided into three main categories:(1) vertical(or normal-incidence) illumination, which can be from the top or back of the wafer/chip, and waveguide-integrated coupling including(2) butt coupling and(3) evanescent coupling. In evanescent coupling the input waveguide can be positioned on top, at the bottom, or lateral to the absorber. Here,to the best of our knowledge, we propose the first concept of Ge-on-Si PD with double lateral silicon nitride(Si_(3)N_(4)) waveguides, which can serve as a novel waveguide-integrated coupling configuration: double lateral coupling. The Ge-on-Si PD with double lateral Si_(3)N_(4) waveguides features uniform optical field distribution in the Ge region, which is very beneficial to improving the operation speed for high input power. The proposed Ge-on-Si PD is comprehensively characterized by static and dynamic measurements. The typical internal responsivity is evaluated to be 0.52 A/W at an input power of 25 mW. The equivalent circuit model and theoretical 3 dB optoelectrical(OE) bandwidth investigation of Ge-on-Si PD with lateral coupling are implemented. Based on the small-signal(S21) radio-frequency measurements, under 4 mA photocurrent, a 60 GHz bandwidth operating at-3 V bias voltage is demonstrated. When the photocurrent is up to 12 mA, the 3 dB OE bandwidth still has 36 GHz. With 1 mA photocurrent, the 70, 80, 90, and 100 Gbit/s non-return-to-zero(NRZ) and 100,120, 140, and 150 Gbit/s four-level pulse amplitude modulation clear openings of eye diagrams are experimentally obtained without utilizing any offline digital signal processing at the receiver side. In order to verify the highpower handling performance in high-speed data transmission, we investigate the eye diagram variations with the increase of photocurrents. The clear open electrical eye diagrams of 60 Gbit/s NRZ under 20 mA photocurrent are also obtained. Overall, the

关键词： waveguide power coupling

10 Gb/s free space optical interconnect with broadcasting capability enabled by a silicon integrated optical phased array

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Chinese Optics Letters 2021年第12期19卷 11-15页

作者： Quan You Daigao Chen Xi Xiao Shaohua Yu National Information Optoelectronics Innovation center China Information Communication Technologies Group Corporation(CICT)Wuhan 430074China State Key Laboratory of optical communication Technologies and Networks China Information Communication Technologies Group Corporation(CICT)Wuhan 430074China

We have proposed and experimentally demonstrated a reconfigurable free space optical interconnect with broadcasting capability based on an eight-channel silicon integrated optical phased *** using the silicon integrated beam steering and broadcasting device,10 Gb/s on-off keying data is transmitted over 15 cm in free space for up to three receivers located in three different *** experimental results show that the optical phased array can be used with broadcasting capability provided to multi-receivers in the card to card optical interconnects,which can significantly reduce device size,system complexity,and total costs.

关键词： optical phased array optical interconnect card to card transmission

The prevalence of red-green color vision deficiency and its related factors in an elderly population above 60 years of age

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International Journal of Ophthalmology(English edition) 2023年第9期16卷 1535-1541页

作者： Hassan Hashemi Aida Shahidi Alireza Hashemi Alireza Jamali Abolghasem Mortazavi Mehdi Khabazkhoob Noor research center for Ophthalmic Epidemiology Noor Eye HospitalTehran ***Iran Noor Ophthalmology research center Noor Eye HospitalTehran ***Iran Rehabilitation research center Department of OptometrySchool of Rehabilitation SciencesIran University of Medical SciencesTehran ***Iran Department of Neurosurgery Sina HospitalTehran University of Medical SciencesTehran ***Iran Department of Basic Sciences School of Nursing and MidwiferyShahid Beheshti University of Medical SciencesTehran ***Iran

AIM:To determine the prevalence of red-green(RG)color vision deficiency(CVD)in an elderly population and its related ***:This report is a part of the Tehran Geriatric Eye Study:a cross-sectional population-based study that was conducted on the elderly population(≥60y)of Tehran,iran using multi-stage stratified random cluster *** study participants underwent complete ocular examination,including the measurement of uncorrected and bestcorrected visual acuity,objective and subjective refraction,and slit-lamp *** color vision was tested using Ishihara plates with the near optical correction in ***:Of the 3791 invitees,3310 participated in the *** data of 2164 individuals were analyzed after applying the exclusion *** prevalence of R-G CVD was 3.73%(95%CI:2.37%–5.09%)in the whole sample;the prevalence of protanomaly,protanopia,and deuteranopia was 1.51%,1.76%,and 0.45%,*** prevalence of R-G CVD was significantly higher in males than in *** prevalence of RG CVD increased with advancing age from 2.91%in the age group 60–64y to 5.8%in the age group≥80y(P=0.070).According to the multiple logistic regression model,male sex,and glaucoma were significantly related to RG *** age and hypertension also had a marginally significant relationship with RG ***:Changes in color vision occur in the elderly due to the aging process and some physiological and pathological *** the change in visual perception may affect the person’s performance,this aspect of the visual system’s function should also be taken into consideration in the examinations of the elderly.

关键词： color vision population-base study protanomaly protanopia deuteranopia elderly

An error-free protocol for quantum entanglement distribution in long-distance quantum communication

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Chinese Science Bulletin 2011年第7期56卷 618-625页

作者： SALEMIAN Shamsolah MOHAMMADNEJAD Shahram Nanoptronics research center Department of Electronics and Electrical Engineering Iran University of Science and Technology

Quantum entanglement distribution is an essential part of quantum communication and computation protocols. Here, linear optic elements are employed for the distribution of quantum entanglement over a long distance. Polarization beam splitters and wave plates are used to realize an error-free protocol for broadcasting quantum entanglement in optical quantum communication. This protocol can determine the maximum distance of quantum communication without decoherence. Error detection and error correc-tion are performed in the proposed scheme. In other words, if there is a bit flip along the quantum channel, the end stations (Alice and Bob) can detect this state change and obtain the correct state (entangled photon) at another port. Existing general error detec-tion protocols are based on the quantum controlled-NOT (CNOT) or similar quantum logic operations, which are very difficult to implement experimentally. Here we present a feasible scheme for the implementation of entanglement distribution based on a linear optics element that does not need a quantum CNOT gate.

关键词：光量子通信量子纠缠协议长距离分发错误检测量子逻辑运算光学元件

67 GHz light-trapping-structure germanium photodetector supporting 240 Gb/s PAM-4 transmission

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Photonics research 2022年第9期10卷 2165-2171页

作者： DAIGAO CHEN HONGGUANG ZHANG MIN LIU XIAO HU YUGUANG ZHANG DINGYI WU PEIQI ZHOU SIYAO CHANG LEI WANG XI XIAO National Information Optoelectronics Innovation center China Information and Communication Technologies Group Corporation(CICT)Wuhan 430074China State Key Laboratory of optical communication Technologies and Networks China Information and Communication Technologies Group Corporation(CICT)Wuhan 430074China Peng Cheng Laboratory Shenzhen 518055China

A light-trapping-structure vertical Ge photodetector(PD)is *** the scheme,a 3μm radius Ge mesa is fabricated to constrain the optical signal in the circular absorption *** from the light-trapping structure,the trade-off between bandwidth and responsivity can be relaxed,and high opto-electrical bandwidth and high responsivity are achieved *** measured 3 d B bandwidth of the proposed PD is around67 GHz,and the responsivity is around 1.05 A/W at wavelengths between 1520 and 1560 *** 1580 nm,the responsivity is still over 0.78 A/W.A low dark current of 6.4 n A is also achieved at-2 V bias *** on this PD,a clear eye diagram of 100 GBaud four-level pulse amplitude modulation(PAM-4)is *** the aid of digital signal processing,240 Gb/s PAM-4 signal back-to-back transmission is achieved with a bit error ratio of 1.6×10^(-2).After 1 km and 2 km fiber transmission,the highest bit rates are 230 and 220 Gb/s,respectively.

关键词： Gb/s trapping structure

Comparison of the effects of acute and chronic psychological stress on metabolic features in rats

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2012年第11期13卷 904-912页

作者： Fatemeh ROSTAMKHANI Homeira ZARDOOZ Saleh ZAHEDIASL Babak FARROKHI Neuroscience research center Shahid Beheshti University of Medical SciencesTehranIran Department of Biology Shahre-Rey BranchIslamic Azad UniversityTehranIran Department of Physiology Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran Endocrine research center Research Institute for Endocrine SciencesShahid Beheshti University of Medical SciencesTehranIran Department of Immunology Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran

This study was aimed to compare the effects of acute and chronic psychological stress on metabolic factors. Forty-two male Wistar rats were divided into control and stressed groups. Stress was applied by a communication box acutely (1 d) and chronically (15 and 30 d). Blood sampling was carried out by retro-orbital-puncture method. The plasma levels of glucose, cholesterol, triglyceride, insulin, and corticosterone were measured. In addition, feed and water intake, latency to eat and drink, adrenal and body weights were determined. Acute and chronic psychological stress did not significantly change basal plasma corticosterone levels. However, immediately (1 min) after acute exposure to stress, plasma corticosterone level increased compared to that before stress exposure. Acute stress increased plasma insulin levels significantly. Fifteen days of stress exposure resulted in plasma glucose increase. Chronic stress significantly increased feed intake, latency to eat, and adrenal weight compared to acute stress. The body weights of both control and stressed groups increased markedly during the experiment. Homeostasis model assessment of insulin resistance (HOMA-IR) index did not change significantly in the stressed group. In conclusion, application of acute and chronic psychological stress leads to different metabolic and/or behavioral changes but the metabolic changes resulting from acute exposure to stress seem to be more pronounced.

关键词： Psychological stress Corticosterone Insulin Glucose Cholesterol Triglyceride