半导体激光器混沌输出的延时特征和带宽

外腔延时特征和带宽是影响混沌激光应用的两个重要参量.本文将一个单路光反馈的半导体激光器输出的激光部分地注入到另一个双路滤波光反馈的半导体激光器中,从而构成一个具有外光注入的双路滤波光反馈半导体激光器系统,即主从激光器系统,用于抑制混沌激光的延时特征并研究其带宽.数值研究了外光注入系数、反馈强度、抽运因子和滤波器带宽对系统输出混沌激光的延时特征的影响,然后将该系统对延时特征的抑制效果和具有外光注入的单路光反馈半导体激光器系统、具有外光注入的双路光反馈半导体激光器系统、具有外光注入的单路滤波光反馈半导体激光器系统以及无光注入双路滤波光反馈半导体激光器系统进行对比和分析,结果表明本文提出的方案对延时特征的抑制效果最好.然后在本文提出的具有外光注入的双路滤波光反馈半导体激光器系统中,延时特征被有效抑制的参数条件下研究系统输出混沌激光的带宽,结果表明,通过适当选择参数的取值,本文提出的方案可以提高系统输出混沌激光的带宽.     

Femtosecond hybrid mode-locked semiconductor laser and amplifier dynamics

We describe the generation of femtosecond high power optical pulses using hybrid passive-active mode-locking techniques. Angle stripe geometry GaAs/AlGaAs semiconductor laser amplifiers are employed in an external cavity including prisms and a stagger-tuned quantum-well saturable absorber. An identical amplifier also serves as an optical power amplifier in a stretched pulse amplification and recompression sequence. After amplification and pulse compression this laser system produces 200 fs, 160 W peak power pulses. We discuss and extend our theory, and supporting phenomenological models, of picosecond and subpicosecond optical pulse amplification in semiconductor laser amplifiers which has been successful in calculating measured spectra and time-resolved dynamics in our amplifiers. We have refined the theory to include a phenomenological model of spectral hole-burning for finite intraband thermalization time. Our calculations are consistent with an intra-band time of approximately 60 fs. This theory of large signal subpicosecond pulse amplification will be an essential tool for understanding the mode-locking dynamics of semiconductor lasers and for analysis of high speed multiple wave-length optical signal processing and transmission devices and systems based on semiconductor laser amplifiers.     

Temperature compensated coupled cavity diode lasers

It has been shown theoretically that the temperature coefficient of the oscillation wavelength in semiconductor lasers can be reduced to zero by coupling an external cavity whose optical length decreases with temperature. Here are described two types of temperature compensated coupled cavity (TC³) diode lasers and their properties calculated in the steady state. In such devices an interference effect due to multi-cavities is expected to cause unstable mode hopping behaviour, but it was found to be settled by choosing an adequate external cavity length.     

Low-Frequency Fluctuation and Frequency-Locking in Semiconductor Lasers with Long External Cavity Feedback

The properties of low-frequency fluctuations in semiconductor lasers with optical feedback from a long external cavity are experimentally studied. Frequency-locking of the laser light output to the injection current modulation is observed when the modulation frequency approaches the external cavity mode. The modulation frequency for the successful frequency-locking is always less than the external cavity mode frequency and the locking domains as a function of the modulation amplitude is asymmetric with respect to the frequency detuning.     

可调谐半导体激光器研究及进展

可调谐半导体激光器是新一代密集波分复用系统以及全光网络中光子交换的关键光电子器件 ,它的运用使得光纤传输系统容量大大增加 ,灵活性和可扩展性大大增强 ,目前已经实现了宽波长范围的连续或准连续调谐 ,并有相应的产品投放市场 .文章介绍了各种基于不同谐振腔结构的可调谐激光器以及各自的调谐机理 ,对不同类型器件在制作以及实际应用中的优缺点进行了比较 .同时总结了国外可调谐半导体激光器的最新进展 ,并对我国可调谐半导体激光器的研制提出了相应的要求     

Double-frequency external cavity laser with a singular optical semiconductor amplifier

Optical properties of an external cavity laser with a semiconductor optical amplifier and two diffraction gratings are described. The laser has been pigtailed and its emission showed two peaks in the output spectrum. The wavelength of the peaks, and in particular the spectral spacing between them, could be controlled by adjusting the reflecting elements in the system. The proposed double-frequency laser may be adopted as a signal source in terahertz generators.     

Nonlinear semiconductor lasers and amplifiers for all-optical information processing

The nonlinear properties of semiconductor lasers and laser amplifiers when subject to optical injection are reviewed and new results are presented for multisection lasers, vertical cavity semiconductor optical amplifiers, and surface-emitting lasers. The main underlying material parameters are outlined and the key design approaches are discussed for both edge-emitting and vertical cavity devices. An overview of theoretical modeling approaches is discussed and a summary of key experimental results is presented. The practical use of optically injected edge-emitting and vertical cavity semiconductor lasers and laser amplifiers is illustrated with examples of applications including, among others, optical logic and chaotic communication.     

Low frequency fluctuation with two external cavity reflectors

The dynamics of a semiconductor laser with two optical feedbacks is studied in this paper. A new set of nonlinear rate equations that can describe external cavity semiconductor lasers with any amount of two optical feedbacks is proposed. It is found that when the laser is biased above the threshold and subjected to one feedback, the other feedback can induce low-frequency fluctuations.     

双光纤光栅外腔半导体激光器相干失效研究

根据双光纤Bragg光栅(FBG)外腔半导体激光器相干失效的物理过程, 运用速率方程和双FBG耦合模理论, 分析了双FBG外腔半导体激光器相干失效产生和控制的条件, 提出了实现和控制双FBG外腔半导体激光器相干失效多模稳定工作的方法. 双FBG外腔半导体激光器在相干失效下具有多模的稳定工作状态, 相干失效长度缩短, 相干失效长度内光谱稳定. 实验测量结果表明, 外腔反射率为3%时, 从非相干失效状态到相干失效状态, 半峰值全宽度从0.5 nm突然展宽到0.9 nm. 在相干失效状态下, 功率稳定, 边模抑制比大于45 dB, 在0℃–70℃工作温度范围内峰值波长漂移小于0.5 nm, 最小相干失效长度小于0.5 m. 双FBG外腔半导体激光器相干失效的应用对提高光纤放大器和光纤激光器的性能具有重要意义. 关键词： 非线性 半导体激光器 双光纤Bragg光栅 相干失效     

基于V型腔光反馈法的半导体激光器线宽压窄和频率锁定初步研究

线宽压窄和频率锁定是提高激光器（特别是半导体激光器）性能的重要手段。在理论分析光反馈时的半导体激光器线宽压窄和频率锁定机理的基础上,建立了一套基于高品质V型光学谐振腔的半导体激光器线宽压窄实验系统,并利用该系统开展了初步实验研究。通过对比无有光反馈情况下的V型腔的透射光扫描线形,初步验证了V型腔用于半导体激光器线宽压窄和频率锁定的可行性,为后续研究奠定了基础。     

Theoretical analysis of a PSK coherent heterodyne optical receiver using external cavity semiconductor lasers

The performance of a PSK heterodyne optical transmission system using external cavity semiconductor lasers as remote and local oscillators in evaluated theoretically. The actual shape of the instantaneous frequency fluctuations power spectral density of the optical oscillators is taken into account, obtaining indications for optimum design of the external optical feedback.     

Grating-Stabilized External Cavity Diode Lasers for Raman Spectroscopy—A Review

Abstract: Conventional Raman techniques require a continuous-wave laser with stabilized wavelength, narrow line width, and sufficient output power. Due to their miniature size and low cost, diode lasers are good choice as light sources for Raman spectroscopy, especially when compact and portable instruments are needed. However, a solitary multimode diode laser has certain drawbacks that limit its use for Raman application. To circumvent these drawbacks, an external cavity can be coupled to the active gain medium of the diode to enhance the laser performance. A grating-based external cavity allows the laser to operate in a single longitudinal mode with greatly reduced line width and stabilized wavelength. This article examines the fundamentals of semiconductor lasers to show the necessity of operating diode lasers in an external cavity for Raman applications. Two feedback grating-based external cavity diode laser (ECDL) designs, viz. Littrow and Littman-Metcalf configurations, are explained. Historic and recent progress in the development of ECDL devices is reported. An updated summary of ECDL-equipped Raman systems applied to fields such as in vivo biomedical studies and in situ process/quality control is provided. Topics on mode-hop-free continuous scanning, wavelength stabilization, and dealing with ambient conditions are discussed.     

Experimental Study on Single Frequency Semiconductor Lasers with Fiber Bragg Reflector External Cavity

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Mode selectivity of multisegment composite-cavity semiconductor lasers

The single longitudinal mode (SLM) characteristics of narrow linewidth long-external-cavity semiconductor lasers has been improved significantly by using a multisegment composite-cavity configuration. In this paper, the mode selectivities of two-segment, three-segment and four-segment cavity semiconductor lasers have been analysed and compared. In experiments, a four-segment composite cavity laser exhibits SLM oscillation with side-mode suppression ratio of 30 dB even for total external cavity length of 75 cm. The oscillation linewidth is less than 200 kHz.     

Semiconductor mode-locked lasers as pulse sources for high bit rate data transmission

Semiconductor mode-locked lasers are evaluated as pulse sources for high bit rate data transmission. This chapter describes the requirements of OTDM sources for high bit rate data transmission, compares various OTDM source technologies, describes three semiconductor mode-locked laser cavity designs, explains the impact of timing jitter and amplitude noise on OTDM performance, illustrates how to characterize noise of OTDM sources using rf and optical techniques, shows how to interpret the noise measurements, and finally discusses semiconductor mode-locked laser cavity optimizations that can achieve low noise performance.     

Recent advances in laser self-injection locking to high-Q microresonators

The stabilization and manipulation of laser frequency by means of an external cavity are nearly ubiquitously used in fundamental research and laser applications. While most of the laser light transmits through the cavity, in the presence of some back-scattered light from the cavity to the laser, the self-injection locking effect can take place, which locks the laser emission frequency to the cavity mode of similar frequency. The self-injection locking leads to dramatic reduction of laser linewidth and noise. Using this approach, a common semiconductor laser locked to an ultrahigh-Q microresonator can obtain sub-Hertz linewidth, on par with state-of-the-art fiber lasers. Therefore it paves the way to manufacture high-performance semiconductor lasers with reduced footprint and cost. Moreover, with high laser power, the optical nonlinearity of the microresonator drastically changes the laser dynamics, offering routes for simultaneous pulse and frequency comb generation in the same microresonator. Particularly, integrated photonics technology, enabling components fabricated via semiconductor CMOS process, has brought increasing and extending interest to laser manufacturing using this method. In this article, we present a comprehensive tutorial on analytical and numerical methods of laser self-injection locking, as well a review of most recent theoretical and experimental achievements.     

Complex dynamics in delay-differential equations with large delay

We investigate the dynamical properties of delay differential equations with large delay. Starting from a mathematical discussion of the singular limit τ → ∞, we present a novel theoretical approach to the stability properties of stationary solutions in such systems. We introduce the notion of strong and weak instabilities and describe a method that allows us to calculate asymptotic approximations of the corresponding parts of the spectrum. The theoretical results are illustrated by several examples, including the control of unstable steady states of focus type by time delayed feedback control and the stability of external cavity modes in the Lang-Kobayashi system for semiconductor lasers with optical feedback.     

Multiple air-gap filters and constricted mesa lasers – material processing meets the front of optical device technology

Real three-dimensional material structures enable enormous perspectives in the functionality of advanced electronic and optoelectronic III/V semiconductor devices. We report on the technological implementation of surface-micromachined III/V semiconductor devices for optoelectronic applications. Considering fabrication technology, the general principles can be reduced to three fundamental process steps: deposition of a layered heterostructure on a substrate, vertical structurization and horizontal undercutting by selectively removing sacrificial layers. Very useful quality-control elements for precise process control are presented. The basic principles are applied and illustrated in detail by presenting two selected optoelectronic examples. (i) The fabrication technology of buried mushroom stripe lasers is shown. Bent waveguides on homogeneous grating fields are used to obtain chirped gratings, enabling a high potential to tailor specific performances. Excellent optical properties are obtained. (ii) The fabrication technology of vertical optical cavity based tunable single- or multi-membrane devices including air gaps is shown. Record optical tuning characteristics for vertical cavity Fabry–Pérot filters are presented. Single parametric wavelength tuning over 142 nm with an actuation voltage of only 3.2 V is demonstrated. PACS 85.60.-q; 87.80.Mj; 68.65.Ac     

Circular grating DFB and DBR semiconductor lasers: threshold current analysis

The threshold current is analyzed for distributed feedback (DFB) and distributed Bragg reflector (DBR) semiconductor lasers with circular gratings. It is shown that in circular grating DFB lasers, the threshold current becomes minimum at a certain cavity radius, while in circular grating DBR lasers it increases monotonically as the active region radius increases.