Switching of a Semiconductor Laser with Multi-Detuned Optical Inputs by Controlling Injection Current

The multistability of a Fabry-Perot semiconductor diode laser for an injection current is presented when multi-optical inputs detuned from the cavity-resonant wavelength of a semiconductor laser are injected. m+1 Multi-stable states are shown to be produced in the optical output versus injection current characteristics for m detuned optical inputs. It is shown that optical output can be switched in any one of the optical input wavelengths in a relatively fast response time by applying injection current pulses. Analytical expression based on linear stability analysis is presented to predict the switching time to free oscillating mode, and larger optical input power and detuning are effective to shorten the switching time. The results here are believed to be useful to extend wavelength switching to a scope of electronic manipulation without modulation of optical inputs and can be applicable to actual devices.     

一种大功率窄脉冲半导体激光器测试台的研制

大功率窄脉冲半导体激光器主要光电性能参数为:输出峰值光功率、阈值电流、正向电压、上升时间、峰值波长、光谱半宽、半强度角.根据激光制导系统对大功率窄脉冲激光器参数的特殊测试要求,研制一种大功率窄脉冲激光器测试平台,将小型化大功率激励器功放模块、大范围可调DC-DC模块、信号源板、激光器座、光学准直镜集成在一个平台上,与峰值功率计、光谱仪、CCD摄像机等仪器配合,可测出大功率窄脉冲激光器的峰值功率、峰值波长及波长随温度变化的漂移特性、发光芯均匀性等参数.介绍了大功率窄脉冲激光器测试台的特点,并对测试结果作了论述.     

Tunable 19 × 10 GHz L-band FP-SOA based multi-wavelength mode-locked fiber laser

We present a multi-wavelength mode-locked fiber ring laser incorporating a semiconductor optical amplifier (SOA) and a Fabry-Perot semiconductor optical amplifier (FP-SOA). Because the gain of the SOA is depleted by an external injection optical signal, the SOA acts as a loss modulator. The FP-SOA serves as a tunable comb filter. The presented laser source can generate 19 synchronized wavelength channels with the extinction ratio of about 21 dB, each mode-locked at 10 GHz, and mode-locked pulse width is about 40 ps. Oscillation wavelengths band can be tuned by adjusting the bias current of the SOA, and wavelength spacing also can be changed by using a tunable optical delay line (ODL) or a temperature controller. The polarization-insensitive devices ensure that the output power is rather stable. This fiber laser has potential applications in longer waveband (L-band) within the low-attenuation window.     

一种测量GaAs-GaAlAs行波激光放大器增益特性的实验方法

本文报导了一种测量光耦合效率η的新实验方法。这个方法是建立于p-n结短路光电流原理上的。本文推导出适合于行波激光放大器的光耦合效率的公式。短路光电流用一检流计测量,利用公式获得光耦合效率的实验值。利用实验所测光耦合效率,测量了行波激光放大器的增益随注入电流变化的规律,其结果和实验符合。另外本文还介绍了在脉冲注入电流条件下测行波半导体激光放大器增益的实验方法。     

Design optimization of all-optical actively mode-locked ring laser based on cross-gain modulation in a semiconductor optical amplifier

A complete and detailed model is presented that describes the main physical phenomena that occur in an actively mode-locked fiber ring laser based on cross-gain modulation in a semiconductor optical amplifier employed as both the gain medium and mode-locking element. The relationship between key laser parameters and the output pulse characteristics is numerically analyzed to provide simple design rules and derive a set of necessary operational conditions. The adoption of these rules and the satisfaction of these conditions enables the optimization of the laser performance and the generation of short and high energy mode-locked output pulses.     

Influence of the bias current on the output characteristics of a mode-locked fiber ring laser consisting of two SOAs

In this paper, after obtaining the mode-locked pulse shape with self-reproduction theory, the influence of the bias current on the output characteristics of a backward-optical-injection harmonic mode-locked fiber ring laser consisting of two semiconductor optical amplifiers (SOAs) has been numerically investigated. The results show that the mode-locked pulse with high peak power and narrow width can be obtained through reasonably adjusting the bias currents of the two SOAs.     

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.     

宽输出电压的半导体激光器驱动电源研究

介绍了一种大功率、宽输出电压范围的半导体激光器脉冲驱动电源的设计方法。根据半导体激光器脉冲驱动电源高电压、大电流的工作特性需求,脉冲放电环节采用多模块级联与功率开关管线性控制脉冲放电相结合的拓扑结构,这样既实现了脉冲电流平滑稳定,又提高了输出电压等级与功率。充电环节采取LCC谐振变换器结构,其抗负载短路和开路的能力非常适用于脉冲放电场合。该脉冲电源输出参数为:电压0~1000 V,电流1~160 A,脉宽200~250 μs,频率100 Hz内可调,具备较宽泛灵活的输出范围,可适应不同规模的激光二极管阵列。最后,分别通过单模块、两模块与三模块小功率级联型驱动实验验证了采用多模块级联与功率开关管线性控制脉冲放电相结合方法的可行性。     

Generation of 10-GHz duty-cycle tunable square optical pulse in an SOA-based mode-locked fiber laser

We demonstrate the generation of 10-GHz optical square pulses by injecting a picosecond pulse train into an SOA-based mode-locked fiber laser. The novel scheme exploits nonlinear effects and gain saturation phenomenon in the semiconductor optical amplifier (SOA). This technique uses gain-compression dynamics between the input pulses and the generated ones in gain-saturated SOA to form square pulses. The center wavelength of the generated optical square pulse can be tuned from 1530 to 1570 nm by adjusting the center wavelength of the optical band pass filter (OBPF) in the SOA-based mode-locked fiber ring laser. The duty cycle of the output pulse can be tuned from 12.7 to 88.4%, which strongly depends on the input power and intra-cavity power.     

线性调频半导体激光器自混频干涉理论模型

使用半导体激光器在弱反馈条件下的动力学理论,建立了线性调频半导体激光器的自混频干涉理论模型.基于该模型,分析了激光器振荡频率偏移与输出功率变化特性.通过测量激光器输出功率谱,可以得到激光器前端面与被测目标之间的距离.     

Broadly Tunable SOA-Based Active Mode-Locked Fibre Ring aser by Forward Injection Optical Pulse

We present a broadly tunable active mode-locked fibre ring laser based on a semiconductor optical amplifier （SOA）, with forward injection optical pulses. The laser can generate pulse sequence with pulsewidth about 12ps and high output power up to 8.56 dBm at 2.5 GHz stably. Incorporated with a wavelength-tunable optical bandpass filter, the pulse laser can operate with a broad wavelength tunable span up to 37nm with almost constant pulsewidth. A detailed experimental analysis is also carried out to investigate the relationship between the power of the internal cavity and the pulsewidth of the output pulse sequence. The experimental configuration of the pulse laser is very simple and easy to setup with no polarization-sensitive components.     

Short optical pulse generation from laser diodes with directional coupler external cavity

We demonstrate picosecond optical pulse (POP) generation from semiconductor laser diodes (LDs) operating in a novel external cavity configuration. The structure uses a looped directional coupler to form an optical cavity whose end reflectivity is controlled by the coupling constant. The end reflectivity can be varied continuously between 0 and 100%, and the cavity length can be adjusted by changing the loop length. A theoretical model and experimental verification of results on the generation of high-repetition POPS are presented.     

40-GHz wavelength tunable mode-locked SOA-based fiber laser with 40-nm tuning range

A 40-GHz wavelength tunable mode-locked fiber ring laser based on cross-gain modulation in a semiconductor optical amplifier (SOA) is presented. Pulse trains with a pulse width of 10.5 ps at 40-GHz repetition frequency are obtained. The laser operates with almost 40-nm tuning range. The relationship between the key laser parameters and the output pulse characteristics is analyzed experimentally.     

光导开关非线性导通时的载流子累加效应

利用半导体激光器作为触发源,对砷化镓光导开关进行了实验研究,重点研究了载流子累加效应对开关输出特性的影响。实验结果表明,光导开关的导通机制与内部载流子数的多少直接相关,当开关中的载流子数积累到雪崩碰撞电离条件,开关就会发生非线性导通。采用低能量光脉冲序列触发光导开关,获得了高功率输出,降低了开关非线性导通时的触发光能和偏置电压,对于光导开关的应用具有重要意义。     

Optical Multistability and Wavelength Switching of a Fabry-Perot Semiconductor Laser with Multi-Detuned Light Injections

Optical multistability of a Fabry-Perot semiconductor laser is analyzed when multi-optical inputs detuned from the cavity-resonant wavelength of a semiconductor laser are injected. Many split branches are shown to be produced in the optical output versus optical input characteristics for different detuned optical inputs. It is also shown that optical outputs can be switched in any one of the optical input wavelengths by optical input pulses, based on the optical output versus input characteristics with multi-split branches.     

Spectrum reshaping of amplified pulse in silicon nanowaveguide

A device consisting of a cascaded semiconductor optical amplifier (SOA) and silicon on insulator (SOI) optical waveguide is presented to amplify and reshape the frequency spectrum of optical pulses in the picoseconds time duration. Numerical simulations show that the output spectrum of the amplified pulse by SOA can be effectively reshaped by utilizing the SOI waveguide. The length of the SOI waveguide may be judiciously adjusted to significantly reduce the frequency chirp of the output pulse from the SOA resulting in reshaping of the output spectrum. We find that the property of pulse spectrum is sensitive to the input pulse power and its temporal width.     

超短光脉冲发生器的研制

本文叙述了用半导体激光器产生光脉冲的基本原理,介绍了用电脉冲驱动AlGaAs/GaAs双异质结激光器产生ps光脉冲的线路原理及实验结果。     

干涉测量用半导体激光器驱动电源

设计了一种可调制的高稳定度半导体激光器驱动电路。该电路的直流稳定度高达1.5×10-5，输出电流在0～200mA内连续可调，长时间工作（12h以上）电流变化小于1μA；在直流基础上注入100kHz～300kHz的调制电流，其调制深度为0～100mA连续可调，可实现在激光干涉测量中对光波频率和光波强度的调制。将该电路驱动的光栅外腔半导体激光器和辅助温度控制电路应用于光干涉测量技术中，得到了功率稳定、波长单一的激光输出，解决了激光器的跳模现象，完成了对远距离微小振动（纳米量级）的测量。     

长波红外无线激光通信脉冲宽度调制实验研究

为实现长波红外无线激光通信,建立了基于脉宽调制的长波红外无线激光通信系统模型,对系统性能进行了分析,给出了系统误码率的计算公式.搭建了实验系统,对CO_2激光器的平均输出光功率随占空比的变化情况进行了分析,对不同占空比条件下接收端对应的激光平均脉冲宽度以及脉冲宽度受噪声影响的随机变化情况进行了分析,得到了激光输出平均光功率、平均脉冲宽度与占空比之间的关系,以及脉宽的分布规律,并将实验结果与理论分析结果进行了对比,在此基础上得到了脉宽最佳判决门限和系统各类工作参数同误码率之间的关系.结果表明,基于CO_2激光器的脉冲宽度调制能够实现长波红外无线激光通信.     

基于半导体光放大器的光脉冲压缩方案的研究

对一种基于半导体光放大器(SOA)和普通单模光纤的光脉冲压缩方案进行了理论分析和实验验证.建立了该方案的理论分析模型,并在此基础上数值模拟了光脉冲的传播过程.计算结果表明,通过合理选取单模光纤的长度,可使50 ps光脉冲压缩到5 ps.实验表明利用普通单模光纤群速度色散导致的脉冲啁啾抵消SOA自相位调制引起的脉冲啁啾,实现了色散补偿及脉冲压缩.