Injection lasers for multichannel optical communication

Injection lasers are suitable sources of radiation for optical communication systems. The output characteristics of III-V compound and mixed crystal III-V compound injection lasers for0.64-1.1-muspectral range are described. In order to improve the spectral output (and to increase the threshold for the appearance of adjacent modes) composite cavities were successfully used. Such a cavity contains the diode and a passive transparent flat plate, which serves as an additional selective component in the feedback circuit of the laser. A 96-channel telephone link was tested in the laboratory using four lasers (wavelengths 0.74, 0.78, 0.85, and 0.91μ) in one beam. The method of combining and separating the four spectral channels at the transmitter and receiver, respectively, as well as the results of the experiments are described.     

Stability enhancement for dual-order Raman fiber lasers

A new laser regime for second-order pumping applications is described. Our laser is a dual-output-wavelength Raman fiber laser that generates a low-power first-order-pump line and a high-power second-order-pump line together. We demonstrate how using four-wave mixing combined to Raman gain in the laser cavity permits better stability of the first-order-pump laser line.     

光通信系统中新型可调谐半导体激光器的设计

为了适应当前光通信系统对波长可调谐激光器的需求,提出用游标效应来实现波长可调谐的激光器,设计了一种功率稳定且频率可调的三段式开槽法布里-珀罗结构可调谐半导体激光器,给出了系统结构的设计原理,并进行了理论分析和实验验证。取得了三段式开槽法布里-珀罗结构可调谐半导体激光器激射谱叠加图数据,利用光纤延迟自外差法测量激光器线宽,对比了3种不同激光器的线宽测量曲线。结果表明,基于游标效应设计的新型开槽法布里-珀罗可调谐半导体激光器波长调谐机制简单方便,且具有很好的单模性和信道切换能力。该研究在未来的光通信领域中具有一定的应用价值和实际意义。     

Semiconductor lasers for coherent optical fiber communications

The current status of semiconductor lasers used in coherent optical fiber communications is reviewed for nonexperts in the field. The issues of spectral purity, tuning, modulation, and advanced fabrication methods for photonic integration are discussed, with examples drawn from current experimental devices     

Spectral modeling of Raman fiber lasers

This letter describes a model of Raman fiber lasers, based on the four-wave mixing interaction between the laser modes. The results predict the laser spectral shape and output power with good accuracy.     

Noise and distortion characteristics of semiconductor lasers in optical fiber communication systems

The distortion and noise characteristics of semiconductor lasers in connection with optical fibers are reviewed. In particular, the intrinsic distortions and noise of semiconductor lasers together with the partition noise are discussed followed by a discussion on the influence of reflections. Modal noise phenomena due to the interference pattern at the endface of optical fibers are treated with respect to noise and distortions. Finally, the influence of polarization coupling in single-mode fibers on the resulting transmission behavior is discussed.     

Theoretical model of optical fiber secure communication system with chaotic multiple-quantum-well lasers

Chaotic synchronization of injected multiple-quantum-well lasers of optical fiber system and a theoretical model of optical fiber chaotic secure communication system are presented by coupling a chaotic multiple-quantum-well laser synchroniza- tion system and a fiber channel. A new chaotic encoding method of chaos phase shift keying On/Off is proposed for optical fiber secure communications. Chaotic synchronization is achieved numerically in long-haul fiber system at wavelength 1.55 μm. The effect of the nonlinear-phase of fiber is analyzed on chaotic signal and synchronization. A sinusoidal signal of 0.2 GHz frequency is simulated numerically with chaos masking in long-haul fiber analog communication at wavelength 1.55 μm while a digital signal of 0.5 Gbit/s bit rate is simulated numerically with c1haos masking and a rate of 0.05 Gbit/s are also simulated numerically with chaos shift keying and chaos phase shift keying On/Off in long-haul fiber digital communica- tions at wavelength 1.55 μm     

高功率光纤激光器

1、引言。所谓高功率光纤激光器是相对于光纤通讯中作为载波的低功率光纤激光器而言(功率为mW级)，是定位于机械加工、激光医疗、汽车制造和军事等领域的高强度光源。高功率光纤激光器巧妙地将光纤技术与激光原理有机地融为一体，铸造了21世纪最选进和最犀利的激光器。即使是在激光技术发达的国家，光纤激光器也是尖端、神秘和充满诱惑的代名词、2002年6月，光纤激光器空降中国，震撼了中国激光学术界和产业界，并引起了至尊院士的关注。     

用于光纤通信的光开关研究进展

针对目前光纤通信系统对光开关的迫切需求,从器件的新工艺、新材料和新机理等方面综述了光开关与光开关列阵的研究进展状况。     

Properties of fiber Raman amplifiers and their applicability todigital optical communication systems

Bit error rate performances of fiber Raman amplifiers both as booster amplifiers and as detection preamplifiers are studied in intensity modulation/direct detection optical communication systems. It is theoretically shown that, in the booster amplifier application, receiver sensitivity degradation due to amplification can be made less than 0.2 dB for signal-to-noise power ratio larger than 20 dB, and thus an allowable transmission line loss can be increased approximately by the value of Raman gain. For detection preamplifier use, receiver sensitivities in the Raman preamplifier system are numerically calculated in terms of minimum detectable signal power at 100-Mbit/s and 2-Gbit/s bit rates. In both bit rates, it is shown that, for a Raman gain greater than 20 dB, minimum detectable signal power can be improved by more than 15 dB over the conventional detection level without Raman amplification. Preliminary experiments are carried out using a 1.32-μm Nd:YAG laser and a 1.4-μm laser diode as pump and signal light sources, respectively. The experimental results are in good agreement with theoretical estimations     

Long-wavelength optical fiber communication

Recent research on long-wavelength lightwave communication utilizing the wavelength region between 1.3 and 1.6 µm is reviewed with an eye toward future system development. The attraction of the long-wavelength region is the availability of the ultimately low-loss and wide-band features of the silica fiber, where minimum loss is 0.27 dB/km at a wavelength of 1.3 µm and 0.16 dB/km at 1.55 µm. The single-mode fiber has found its first significant applications in long-wavelength systems. The specific characteristics of lightwave components are discussed with focus on physical fundamentals. The practical performance of fibers and lightwave devices is surveyed. The dynamic properties of long-wavelength laser diodes are discussed in relation to fiber characteristics. The noise characteristics of long-wavelength detectors are considered for the purpose of specifying the repeater spacing. Some system studies are reviewed, for example, 1.3-µm-wavelength lightwave systems, which have demonstrated bandwidth-distance products of about 40 GHz ċ km. Various approaches to extend the capacity of long-wavelength lightwave transmission are given. In the future, the 1.5-µm wavelength system could operate at the lowest loss wavelength region extending from 1.5 to 1.65 µm. Much higher performance, for example, bandwidth-distance products of 185 GHz ċ km, achieved by further continuation of research and development on lightwave sources as well as fibers. Because of the author's familiarity with work in Japan, that work is emphasized and most frequently cited.     

无线光通信

随着信息化社会的到来,通信技术得到了日新月异的发展,无线光通信具有施工、带宽、成本等多方面的优点,但仍然存在影响传输可靠性的一些问题,如果这些问题能得到解决,那么必能发挥最大潜能和优势,随着无线光通信技术的不断研究和完善,将会得到更加广泛的应用.     

Bandwidth reduction in CW fiber Raman lasers

The oscillation linewidth of CW fiber Raman lasers has been reduced from typical uncontrolled values Of 200 GHz (approximately 0.2 nm for 528 nm radiation) to 9 GHz by employing prisms, gratings, and etalons in various resonator configurations. Further reduction is limited by four-wave mixing and stimulated Brillouin scattering. Although four-wave mixing limits bandwidth reduction, the results demonstrate the use of this nonlinear process for intensity stabilization.     

光纤纤芯通信质量检测系统的设计与应用

针对人工检测纤芯通信质量不易检测的特点,结合单位业务实际和对纤芯通信质量检测管理需求,设计了一套基于OTDR的光纤传感节点感知光缆纤芯质量的光纤纤芯质量检测系统。该系统主要采用多通路OTDR光缆监测,综合应用光时域反射、计算机和地理信息系统技术,利用移相采样技术和跨阻偏压可变接收机技术提升了OTDR模块的性能并有效地控制了成本,实时获得被测光缆纤芯通信质量信息,有效提高光纤通信网的可靠性和使用效益。     

非二进制LDPC码编码调制在光纤通信中的应用

为满足100Gb/s光纤通信的需求,提出了非二进制LDPC码编码调制(NB-LDPC-CM)方案.该方案通过使用频谱效率调制以及非二进制前向纠错LDPC码,提供了一种在高总比特率下实现可靠通信的前向纠错机制.与现有的BI-LDPC-CM方案相比,该方案在误比特率(BER)为10-7的情况下,采用16点、32点、和64点四维星座图时,额外提供的净编码增益分别为0.26dB、1.14dB和2.14dB.     

光纤通信系统的军事应用初探

随着现代战争对通信直观性与实时性的要求不断增加,现代军事通信的信息处理、传输和贮存也渐渐融为一体。对于这种形势,光纤通信系统因其自身优秀的性能,它应用将极大程度地满足这些要求,光纤通信系统在军事领域的应用是一种时代的趋势,文章对此进行了初步的探究。     

多波长通信用声光滤光器

声光滤光器（ＡＯＴＦ）是一种新型光学滤光元件,可望用于多波长光通信波分复用网络技术中的波长快速调谐,它具有速度快,模式可变,光谱范围宽,可反馈控制等优点。     

Novel high-efficiency concentrator for optical fiber communication

A novel high-efficiency concentrator based on nonimaging optics has been designed and fabricated with micromachining technique. The shape of the concentrator utilizes compound parabolic concentrator (CPC), which can concentrate the all rays that have the angles less than a critical angle &thetas;_c. The theoretical concentration efficiency was calculated by ray trace simulation considering the reflectance of the concentrator's reflective layer. The metal reflection layer of reflectance 95% was formed by gold-nickel mirror plating method in a glass hole. As a result, the concentration efficiency of the concentrator was measured as 89%     

Polarization effects in fiber Raman and Brillouin lasers

Raman and Brillouin gains in fibers are a factor of 2 higher if linear polarization is maintained. Birefringent single-mode fibers are used to demonstrate this gain difference. Threshold powers of 200 mW have been achieved in Raman oscillators.     

Theory and design of double-cavity Raman fiber lasers

We introduce the concept of the double-cavity Raman fiber laser (DC-RFL) with three Bragg gratings at the laser wavelength. In such RFLs, the threshold pump power and the conversion efficiency at large pump powers can be designed independently of each other, whereas in ordinary single-cavity RFLs these two optimization criteria collide. The particular behavior of DC-RFLs is interpreted, and a simple technique for the numerical simulation and an analytical relation for the threshold pump power of these devices are presented.