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光通信

·編者按·

光通信（Optical Communication）是以光波為載波的通信方式。光波和無線電波同屬電磁波，但光波的頻率比無線電波的頻率高，波長(zhǎng)比無線電波的波長(zhǎng)短。因此，它具有傳輸頻帶寬、通信容量大和抗電磁干擾能力強(qiáng)等優(yōu)點(diǎn)。光通信按傳輸媒介的不同，可分為有線光通信和無線光通信（也叫大氣光通信）。常用的光通信有：大氣激光通信、光纖通信、藍(lán)綠光通信、紫外線通信等。

自1972年我國(guó)開始光通信技術(shù)的研究至今，已經(jīng)經(jīng)歷了40年的歷程。從1982年第一個(gè)光通信實(shí)用化工程算起，也有了30年的發(fā)展。經(jīng)過幾代光通信技術(shù)人員的不懈努力，目前光通信已成為我國(guó)與國(guó)際先進(jìn)水平差距最小的科技領(lǐng)域之一。我國(guó)現(xiàn)網(wǎng)的光通信技術(shù)應(yīng)用水平已經(jīng)站到了國(guó)際前列；從產(chǎn)業(yè)的角度看，我國(guó)也成為光通信產(chǎn)品的生產(chǎn)大國(guó)，當(dāng)然還難以說是強(qiáng)國(guó)；在光通信前沿技術(shù)的研究方面，與國(guó)際先進(jìn)水平卻有著較大的差距。光纖通信技術(shù)目前仍處在高速發(fā)展期，我國(guó)在光纖通信技術(shù)方面取得了很大進(jìn)步，但與國(guó)際水平的差距正被逐步拉大。我們正面臨嚴(yán)峻的挑戰(zhàn)，重?fù)?dān)落在各位同仁肩上。我相信，只要大家共同努力，一定會(huì)在光纖通信技術(shù)方面不斷有新的突破，攀登到世界光通信技術(shù)之巔。

本專題得到了柯熙政教授（西安理工大學(xué)光電工程技術(shù)研究中心）、陳林教授（湖南大學(xué)信息科學(xué)與工程學(xué)院）的大力支持。

·熱點(diǎn)數(shù)據(jù)排行·

截至2015年12月20日，中國(guó)知網(wǎng)（CNKI）和Web of Science（WOS）的數(shù)據(jù)報(bào)告顯示，以“光通信（Optical Communication）、光通信技術(shù)（Optical Communication Technology）”為詞條可以檢索到的期刊文獻(xiàn)分別為3379與22728條，本專題將相關(guān)數(shù)據(jù)按照：研究機(jī)構(gòu)發(fā)文數(shù)、作者發(fā)文數(shù)、期刊發(fā)文數(shù)、被引用頻次進(jìn)行排行，結(jié)果如下。

研究機(jī)構(gòu)發(fā)文數(shù)量排名（CNKI）

研究機(jī)構(gòu)發(fā)文數(shù)量排名（WOS）

作者發(fā)文數(shù)量排名（CNKI）

作者發(fā)文數(shù)量排名（WOS）

期刊發(fā)文數(shù)量排名（CNKI）

期刊發(fā)文數(shù)量排名（WOS）

根據(jù)中國(guó)知網(wǎng)（CNKI）數(shù)據(jù)報(bào)告，以“光通信（Optical Communication）、光通信技術(shù)（Optical Communication Technology）”為詞條可以檢索到的高被引論文排行結(jié)果如下。

國(guó)內(nèi)數(shù)據(jù)庫(kù)高被引論文排行

根據(jù)Web of Science統(tǒng)計(jì)數(shù)據(jù)，以“光通信（Optical Communication）、光通信技術(shù)（Optical Communication Technology）”為詞條可以檢索到的高被引論文排行結(jié)果如下。

國(guó)外數(shù)據(jù)庫(kù)高被引論文排行

·經(jīng)典文獻(xiàn)推薦·

基于Web of Science檢索結(jié)果，利用Histcite軟件選取LCS（Local Citation Score，本地引用次數(shù)）TOP 30文獻(xiàn)作為節(jié)點(diǎn)進(jìn)行分析，得到本領(lǐng)域推薦的經(jīng)典文獻(xiàn)如下。

Free-space optical communication through atmospheric turbulence channels

Zhu,XM; Kahn JM

Abstract:In free-space optical communication links,atmospheric turbulence causes fluctuations in both the intensity and the phase of the received light signal,impairing link performance.In this paper,we describe several communication techniques to mitigate turbulence-induced intensity fluctuations,i.e.,signal fading.These techniques are applicable in the regime in which the receiver aperture is smaller than the correlation length of fading and the observation interval is-shorter than the correlation time of fading.We assume that the receiver has no knowledge of the instantaneous fading state.When the receiver knows only the marginal statistics of the fading,a symbol-by-symbol NIL detector can be used to improve detection performance.If the receiver has knowledge of the joint temporal statistics of the fading,maximum-likelihood sequence detection (MLSD) can be employed,yielding a further performance improvement,but at the cost of very high complexity.Spatial diversity reception with multiple receivers can also be used to overcome turbulence-induced fading.We describe the use of NIL detection in spatial diversity reception to reduce the diversity gain penalty caused by correlation between the fading at different receivers.In a companion paper,we describe two reduced-complexity implementations of the MLSD,which make use of a single-step Markov chain model for the fading correlation in conjunction with per-survivor processing. Orthogonal frequency division multiplexing (OFDM) is a modulation technique which is now used in most new and emerging broadband wired and wireless communication systems because it is an effective solution to intersymbol interference caused by a dispersive channel.Very recently a number of researchers have shown that OFDM is also a promising technology for optical communications.This paper gives a tutorial overview of OFDM highlighting the aspects that are likely to be important in optical applications.To achieve good performance in optical systems OFDM must be adapted in various ways.The constraints imposed by single mode optical fiber,multimode optical fiber and optical wireless are discussed and the new forms of optical OFDM which have been developed are outlined.The main drawbacks or OFDM are its high peak to average power ratio and its sensitivity to phase noise and frequency offset.The impairments that these cause are described and their implications for optical systems discussed. Recent theoretical work has shown that novel quantum states,called two-photon coherent states (TCS),have significant potential for improving free-space optical communications.The first part of a three-part study of the communication theory of TCS radiation is presented.The issues of quantum-field propagation and optimum quantum-state generation are addressed.In particular,the quantum analog of the classical paraxial diffraction theory for quasimonochromatic scalar waves is developed.This result,which describes the propagation of arbitrary quantum states as a boundary-value problem suitable for communication system analysis,is used to treat a number of quantum transmitter optimization problems.It is shown that,under near-field propagation conditions,a TCS transmitter maximizes field-measurement signal-to-noise ratio among all transmitter quantum states; the performance of the TCS system exceeds that for a conventional (coherent state) transmitter by a factor of Ns+1,where Nsis the average number of signal photons (transmitter energy constraint).Under far-field propagation conditions,it is shown that use of a TCS local oscillator in the receiver can,in principle,attenuate field-measurement quantum noise by a factor equal to the diffraction loss of the channel,if appropriate spatial mode mixing can be achieved.These communcation results are derived by assuming that field-quadrature quantum measurement is performed.In part II of this study,photoemissive reception of TCS radiation will be considered; it will be shown therein that homodyne detection of TCS fields can realize the field-quadrature signal-to-noise ratio performance of part I.In part III,the relationships between photoemissive detection and general quantum measurements will be explored.In particular,a synthesis procedure will be obtained for realizing all the measurements described by arbitrary TCS. Although silicon has dominated solid-state electronics for more than four decades,a variety of other materials are used in photonic devices to expand the wavelength range of operation and improve performance.For example,gallium-nitride based materials enable light emission at blue and ultraviolet wave-lengths(1),and high index contrast silicon-on-insulator facilitates ultradense photonic devices(2,3).Here,we report the first use of a photodetector based on graphene(4,5),a two-dimensional carbon material,in a 10 Gbit s-1optical data link.In this interdigitated metal-graphene-metal photodetector,an asymmetric metallization scheme is adopted to break the mirror symmetry of the internal electric-field profile in conventional graphene field-effect transistor channels(6-9),allowing for efficient photo-detection.A maximum external photoresponsivity of 6.1 mA W-1is achieved at a wavelength of 1.55 mu m.Owing to the unique band structure of graphene(10,11)and extensive developments in graphene electronics(12,13)and wafer-scale synthesis(13),graphene-based integrated electronic-photonic circuits with an operational wavelength range spanning 300 nm to 6 μm (and possibly beyond) can be expected in the future. Free-space optical communications (FSO) propagated over a clear atmosphere suffers from irradiance fluctuation caused by small but random atmospheric temperature fluctuations.This results in decreased signal-to-noise ratio (SNR) and consequently impaired performance.In this paper,the error performance of the FSO using a subcarrier intensity modulation (SIM) based on a binary phase shift keying (BPSK) scheme in a clear but turbulent atmosphere is presented.To evaluate the system error performance in turbulence regimes from weak to strong,the probability density function of the received irradiance after traversing the atmosphere is modelled using the gamma-gamma distribution while the negative exponential distribution is used to model turbulence in the saturation region and beyond.The effect of turbulence induced irradiance fluctuation is mitigated using spatial diversity at the receiver.With reference to the single photodetector case,up to 12 dB gain in the electrical SNR is predicted with two direct detection PIN photodetectors in strong atmospheric turbulence.

Keywords:atmospheric turbulence; free-space optical communication; MLSD; spatial diversity reception modulation; orthogonal frequency division multiplexing (OFDM); optical communication atmospheric turbulence; diversity; free-space optics (FSO); gamma-gamma distribution; negative exponential distribution; subcarrier modulation

來源出版物:IEEE Transactions on Communications,2002,50(8):1293-1300

OFDM for Optical Communications

Armstrong,Jean

來源出版物:Journal of Lightwave Technology,2009,27(3):189-204

Optical communication with two-photon coherent states—Part I:Quantum-state propagation and quantum-noise

Yuen,Horace P.; Shapiro,J.H.

來源出版物:IEEE Transactions on Information Theory,1978,24(6):657-668

Graphene photodetectors for high-speed optical communications

Mueller,Thomas; Xia,Fengnian; Avouris,Phaedon

來源出版物:Nature Photonics,2010,4(5):297-301

來源出版物:Journal of Lightwave Technology,2009,27(8):967-973

·推薦綜述·

BPSK subcarrier intensity modulated free-space optical communications in atmospheric turbulence

Popoola,Wasiu O.; Ghassemlooy,Zabih

文獻(xiàn)編號(hào)本領(lǐng)域經(jīng)典文章題目第一作者來源出版物1 Free-space optical communication through atmospheric turbulence channels Zhu,XM IEEE Transactions on Communications,2002,50(8):1293-1300 2OFDM for optical communications Armstrong,Jean Journal of Lightwave Technology,2009,27(3):189-204 3 Optical communication with two-photon coherent states—Part I:Quantum-state propagation and quantum-noise Yuen,Horace P IEEE Transactions on Information Theory,1978,24(6):657-668 4 Graphene photodetectors for high-speed optical communications Mueller,Thomas Nature Photonics,2010,4(5):297-301 5 BPSK subcarrier intensity modulated freespace optical communications in atmospheric turbulence Popoola,Wasiu O Journal of Lightwave Technology,2009,27(8):967-973