Influence of laser phase on 400-Mbit/s coherent optical DPSK system

The influence of laser phase noise on a 400-Mb/s optical DPSK (differential phase-shift keying) system is experimentally investigated with linewidths ranging from 1.2 MHz to 8 MHz. This range corresponds to linewidth to bit rate ratios ϵ of 0.33-2%. The system performance with these nonzero linewidths is evaluated against a negligible linewidth performance baseline. The sensitivity degradation at a bit error rate of 10^-9 increases from 1.8 to 7 dB as ϵ is increased from 0.33-1%. When ϵ is increased beyond 1%, bit error rate floors higher than 10^-9 develop. These findings agree well with the existing theories and allow the generalization of these results to other bit rates, as well as establishing practical criteria for lasers to be used in DPSK systems     

Influence of the nonlinear phase and ASE noise on DPSK balanced optical receiver in optical fiber communication system

The analytical expression of bit error probability in a balanced differential phase-shift keying(DPSK) optical receiver considering nonlinear phase noise and EDFA ASE noise is given,which is very useful to estimate the performance of DPSK balanced and unbalanced receiver in optical communication system.Through analysis,if only nonlinear phase noise is considered,both the balance and unbalanced receivers have the same performances.But if adding the ASE noise of EDFA,the balanced receiver is better.     

Balanced phase diversity receiver in 565 Mbit/s DPSK transmission system

565 Mbit/s DPSK optical transmission experiments with a balanced phase diversity receiver are reported. by employing a bulk optical 90 degrees hybrid in the input stage and a silicon bipolar multiplier IC in the demodulator and AFC stages, a system with a receiver sensitivity of -48.5 dBm and long-term stability was realised.<>     

Signal processing in an optical polarization diversity receiver for560-Mbit/s ASK heterodyne detection

Polarization diversity is an alternative technique for coherent receivers to prevent loss to signal due to variations in the states of polarization (SOP) of the received signal field. It is shown experimentally and theoretically that there is no significant power penalty difference between a receiver with optimally adjusted gains and receivers with linear envelope detection and square-law detection. Experimentally, two amplitude-shift keying (ASK) heterodyne polarization diversity receivers with envelope detectors were demonstrated at 560 Mb/s, one using linear rectifiers, the other using square-law rectifiers. In both cases, the receiver sensitivity of -35 dBm at BER=10 ^-9 was degraded by less than 1 dB as the received signal SOP was varied, in agreement with theory     

Low detection penalty in an optical DPSK heterodyne system using asaturated optical amplifier as phase modulator

A model established from the rate equations of a near traveling-wave optical amplifier (NTWOA) used as a phase modulator shows that the modulation rate is limited by the carrier lifetime to 500 Mb/s and that the worst-case detection penalty is about 0.7 dB. It is then experimentally demonstrated that close control of the injected light polarization can reduce the detection penalty in a DPSK (differential phase-shift keying) heterodyne system, using an NTWOA phase modulator instead of an LiNbO₃ modulator, to 0.6 dB. This device and a balance receiver have allowed the implementation of 282-Mb/s DPSK link operating at 1.522 μm over 242 km of fiber with a 3-dB margin     

Analysis and design of a DPSK optical heterodyne receiver in the presence of laser phase noise and frequency detuning

This paper is concerned with the analysis and design of an improved differential heterodyne optical receiver for differentially-encoded binary PSK (briefly, DPSK) signals in a coherent lightwave communication system. In the first part of the paper, we discuss the relevant design criteria to be employed when dealing with asynchronous heterodyne receivers for ASK, FSK or DPSK optical signals. In particular, we introduce a convenient definition of the signal-to-noise ratio at the data detector input to be assumed as the system performance measure when the non-negligible linewidth of the transmit/receive laser sources are to be taken into account. Following this design approach, we show that by properly modifying the traditional delay-and-multiply DPSK receiver, i. e. by allowing the delay to be a fraction of the symbol interval, we can considerably reduce the performance degradation caused by laser phase noise. We show thus that the superior power-efficiency of DPSK can be traded in favour of a decreased sensitivity to phase noise through a proper choice of the differential detector delay. In this respect, our results reveal that DPSK may still be competitive with other modulation formats even with non-negligible linewidth sources. In the last part of the paper, the behaviour of the optimized DPSK, ASK and large-deviation FSK data demodulators in the presence of a quasistationary frequency detuning of the local laser is also discussed under the same set of conditions as in the previous analysis. The results can be employed to derive accurate design requirements for the AFC loop of the receiver.     

消光比对10Gb/s光接收模块灵敏度的影响

10Gb/s光通信用光接收模块前端常采用APD-TIA组件.理论表明,具有该组件的10Gb/s光接收模块的光灵敏度,主要取决于光纤耦合效率、APD偏置电压、光倍增、过剩噪声和暗电流和消光比等.测试表明,当其它相关因素不变,消光比由5.0dB变到11.0dB时,光接收灵敏度发生2.0～5.0dBm的优化,指出了获得较佳光...     

空间光DPSK发射与自相干接收系统实验

搭建通信速率为10 Gbps的光DPSK调制发射、自相干接收单元实验测试平台。采用光相位调制和自相干接收技术实现光DPSK系统设计。为稳定输出信号解决相位漂移,发射单元设计出自适应增益控制单元和交叉点自适应控制单元。在系统测试平台上,完成差分编码模块、发射单元和自相干接收单元及系统性能测试。实验室环境条件下,测得系统接收单元灵敏度为-48 dBm,通信系统误码率优于1×10-7;误差矢量幅度为7 %,通信性能较好,满足系统设计指标要求。     

用于10Gbit／sSDH光传输系统的光接收机

本文介绍了一种用于１０Ｇｂｉｔ／ｓＳＤＨ光传输系统的光接收机。该接收机的光接口指标可满足ＩＴＵ－ＴＧ．ＳＣＳ建议的要求。已将该接收机用于１０Ｇｂｉｔ／ｓ光纤传输实验。     

GE-PON用光收发模块应力接收灵敏度探讨

介绍了GE-PON用光接收模块应力接收灵敏度相关的国际标准、技术指标和测量原理,报告了10光收发模块的应力接收灵敏度的实测结果,讨论了应力接收灵敏度测试的代价和类似标准的差异.     

新型WDMA-EPON系统OLT端光接收机的研究

文章介绍了一种新型粗波分复用（CWDM）阵列式光接收模块,用于波分多址（WDMA）基于以太网的无源光网络（EPON）的光线路终端（OLT）侧。谊接收模块采用新颖有源、无源混合集成的光电子器件,最终实现了多个波长通道的接收单元电路一体化,因而具有高可靠性、低成本和体积小的特点。在155Mbit／s速率时谊接收机的接收灵敏度优于-34．0dBm。     

116 photons/bit in a 565 Mbit/s optical DPSK heterodyne transmission experiment

A 565 Mbit/s DPSK heterodyne experiment is presented. A sensitivity of -50.0 dBm at the receiver input was achieved, which is the best reported value for this data rate. The experimental data match the theory within 1.4 dB.<>     

High sensitivity 5 Gbit/s optical receiver module using Si IC and GaInAs APD

A 5 Gbit/s optical receiver module was developed by using a wideband transimpedance Si IC and a high gain-bandwidth product GaInAs APD. A 6 GHz bandwidth Si IC utilising a f/sub t/=20 GHz Si MMIC process, bare chip mounting of a Si IC and an APD to minimise parasitic capacitance, made it possible to realise high speed operation and high receiver sensitivity of -31.8 dBm.<>     

Terminals for a high-speed optical pulse code modulation communication system: I. 224-Mbit/s single channel

The design of an experimental single-channel 224-Mbit/s (megabits per second) optical pulse code modulation terminal is described and data are presented which have been obtained with such a terminal using a helium-neon laser operating at 6328 Å. The basic elemets is an optical gate using lithium tantalate whose design and operating characteristics are described.     

10G APD组件的跨阻增益带宽和接收灵敏度

报告了几个10Gb/s APD-TIA组件的光接收灵敏度、眼图和小信号带宽测试结果,讨论了组件跨阻增益-带宽特性和获得最佳灵敏度的方法,指出了10Gb/s信号最低带宽要求和APD-TIA组件带宽要求.     

WDM high speed chirped DPSK fiber optical system transmission modeling in presence of PMD,PDL, and CD

An analytic model is reported to evaluate the electric output signals and their variance (eye diagram) for multichannel high-speed DPSK fiber optical system in presence of polarization mode dispersion (PMD), polarization dependent loss (PDL), and chromatic dispersion (CD). It is also found that even under linear cross talks, the balanced receiver output show a strong asymmetric phenomenon if adjacent channels are nonsynchronous.     

10Gb/s APD-TIA组件的最佳光接收灵敏度

介绍了10Gb/s APD-TIA组件结构和基本特性,分析了APD的最佳光电倍增和APD-TIA组件的最佳接收光灵敏度,报告和讨论了10Gb/s APD-TIA组件光接收灵敏度测量结果,指出了APD光电倍增与器件结构和偏置电压紧密相关,通过仔细调测,在0.85-0.95Vb下可测得最佳光接收灵敏度.     

5 Gbit/s direct optical DPSK modulation of a 1530-nm DFB laser

5 Gb/s direct optical differential-phase-shift-keying (DPSK) modulation of a 1530-nm distributed feedback (DFB) laser is demonstrated using injection current modulation with a bipolar signal format. Delay demodulation is performed using an interferometer with a delay time T equal to the duration of one bit. The input and differentially encoded nonreturn to zero (NRZ) signals are shown. The bipolar modulation current signal is basically the time derivative of the NRZ signal. There was no degradation of the optical DPSK signal due to thermal frequency modulation of the laser. The direct DPSK modulation technique avoids the insertion loss and systems complexity of external DPSK modulators     

Gigabit/s optical receiver sensitivity and zero-dispersion single-mode fiber transmission at 1.55 µm

High-speed pulse response and receiver sensitivity at 1.55 μm were measured at data rates ranging from 400 Mbits/s to 2 Gbits/s, in order to elucidate characteristics of a reach-through p+nn- Ge APD. The p+nn- Ge APD receiver provided a 2 Gbit/s received optical power level of -32.0 dBm at 1.55μm and a 10^-9error rate, which was 4 dB better than the receiving level with a p+n Ge APD. Detector performance at 1.3μm was also studied for comparison with performance at 1.55μm. Single-mode fibers, which have 0.54 dB/km loss and zero dispersion at 1.55μm, and an optical transmitter-receiver, whose repeater gain is 29.2 dB, have enabled 51.5 km fiber transmission at 2 Gbits/s. The transmission system used in this study has a data rate repeater-spacing product of 103 (Gbits/s) . km at 1.55μm. Optical pulse broadening and fiber dispersion were also studied, using 1.55 and 1.3μm dispersion-free fibers. Future repeater spacing prospects for PCM-IM single-mode fiber transmission systems are discussed based on these experimental results.