Synchronized harmonic frequency mode-locking with laser diodes through optical pulse train injection

An ultrahigh-frequency optical pulse train from a monolithic mode-locked laser diode was stabilized by a novel method. When a stabilized optical pulse train was injected into a passively mode-locked laser diode whose repetition frequency was an integer multiple of the injected one, the output optical pulse train was harmonically synchronized and highly stabilized. This kind of operation was observed up to 40 GHz with 1 GHz optical pulse injection.     

高重复频率的增益开关Nd3+:YVO4+KTP绿光激光器

摘要：介绍了可连续和脉冲双模式输出的绿光激光器。用一只半导体激光器端面抽运Nd3+:YVO4+KTP胶合晶体,通过腔内倍频,获得光-光转换效率为19%的连续绿光激光输出。利用增益开关技术,改变注入激光器的电脉冲波形,可以得到方波、正弦波或三角波的绿光激光脉冲输出;调节激光器驱动电流的幅度和占空比可改变输出激光脉冲的强度和脉宽;改变驱动电源的重复频率可以使输出绿光激光脉冲的重复频率连续可调,最大重复频率可达2MHz。在重复频率为560kHz时,获得了输出绿光激光脉冲宽度为74ns、峰值功率为285mW、振幅噪声小于3%。     

高重复频率的增益开关Nd3+:YVO4+KTP绿光激光器

为了设计一种可连续和脉冲双模式输出的绿光激光器,采用一只半导体激光器端面抽运Nd3+:YVO4+KTP胶合晶体,通过腔内倍频,获得光-光转换效率为19%的连续绿光激光输出.利用增益开关技术,改变注入激光器的电脉冲波形,可得到方波、正弦波或三角波的绿光激光脉冲输出;调节激光器驱动电流的幅度和占空比可改变输出激光脉冲的强度和脉宽;改变驱动电源的重复频率可以使输出绿光激光脉冲的重复频率连续可调,最大重复频率可达2MHz.在重复频率为560kHz时,获得了输出绿光激光脉冲宽度为74ns、峰值功率为285mW、振幅噪声小于%.研究表明,利用增益开关技术可以获得重复频率和窄脉冲宽度的绿光激光脉冲.     

New Fiber Optic Analog Baseband Transmission Plan for Color TV Signals

A new fiber optic baseband analog transmission plan is proposed. It arranges the original signal into a pulse train for driving the laser diode to generate baseband components at the transmitter. The receiver can be just the same as those used in conventional direct linear intensity modulation systems using light emitting diodes (LED). Advantages of this new plan are (i) potentially cheap fibers can be used, since the plan requires neither an extra wide bandwidth nor special light acceptance conditions, (ii) long repeater spacings can be attained, since abundant light can be coupled into fibers using laser diodes and also the simple structures required for fibers are suitable for realizing low transmission losses, and (iii) the transmitter and receiver can be quite simple. Some candidate pulse arranging plans for generating baseband components are investigated. A pulse frequency arranging plan and pulse width arranging plan seem to be promising for efficient picture transmissions. An experiment using pulse frequency arrangement proves the theory developed here to attain a color TV transmission using a 10 km long step index low-loss fiber for a signal to noise ratio of 44 dB. Future improvements are expected by redesigning the transmitter and receiver and also by improving the mode stability of laser diodes.     

Transform-limited 480 GHz colliding-pulse modelocked laser diode

Generation of a 480 GHz optical pulse train from a short-cavity colliding-pulse modelocked laser diode is reported. Cavity loss reduction by high-reflection coatings of both laser facets was found to he effective for pulse shortening. The pulsewidth of the laser output was 0.52 ps and the time-bandwidth product was 0.31, indicating that the laser output was nearly transform-limited     

Generation of ultrahigh-speed tunable-rate optical pulses usingstrongly gain-coupled dual-wavelength DFB laser diodes

A novel and simple method to generate a variable-rate, ultrahigh-speed optical pulse train is demonstrated using a dual-wavelength, strongly gain-coupled distributed-feedback laser diode. The repetition rate of the optical pulse train is continuously tunable from 25 to 80 GHz and no high-speed electronics are required in this method     

Spectral measurement of the noise in continuous-wave mode-lockedlaser pulses

A theoretical analysis of the noise of a periodic optical pulse train is presented. It is shown that the amplitude fluctuation, the pulsewidth fluctuation, the pulse timing jitter, and the cross correlations between any two of these three noise parameters can be separately quantified by comparing the noise power spectra of the fundamental pulses and those of the second-harmonic pulses. The noise characteristics of an actively mode-locked Nd:YLF laser are presented to demonstrate this technique     

Pulse stabilisation in harmonically FM modelocked erbium fibre ring laser with DFBLD

A new pulse stabilisation scheme for a harmonically frequency modulated (FM) modelocked erbium fibre ring laser using a distributed feedback laser diode (DFBLD) is presented. More than 65 dB supermode noise suppression in the RF spectrum was obtained with the proposed method. Effective reduction of supermode noise can be accomplished as the DFBLD in the fibre laser acts not only as a fast-gain saturated medium but also as an optical bandpass filter for suppressing supermode noise in a harmonically modelocked laser system.     

Generation of 10 GHz transform-limited pulse train from fibre ringlaser using Fabry-Perot semiconductor as modulator

A train of nearly transform-limited picosecond pulse trains at ~10 GHz is generated from a fibre ring laser with a Fabry-Perot semiconductor laser as a modulator. This simple configuration can generate pulses of much better quality than those obtained by direct gain-switching of the same laser diode     

Generation of synchronized subterahertz optical pulse trains byrepetition-frequency multiplication of a subharmonic synchronousmode-locked semiconductor laser diode using fiber dispersion

We describe the generation of a synchronized, low-jitter, subterahertz optical pulse train by repetition-frequency multiplication of a subharmonic synchronous mode-locked semiconductor laser diode using the group-velocity dispersion (GVD) of optical fiber. A 49-196 GHz optical pulse train was generated with low intensity fluctuation and with low timing jitter, by adjusting fiber length in accordance with the mode-locking frequency and the fiber's GVD     

基于国产芯片的千兆皮秒脉冲激光器模块研制

皮秒脉冲光源是量子密钥分配系统核心器件。为了实现皮秒脉冲光源的国产化,基于国产芯片研制了一种千兆皮秒脉冲激光器模块。该模块采用比例-积分-微分算法控制温度,使光波长漂移在0.01nm以内,使用外部光电二极管探测光功率,反馈调整激光管驱动电流,进行了实验验证。结果表明,利用国产单片机精确控制恒流源和窄脉冲电路驱动激光管发光,输出光脉冲频率达到1.25GHz,脉冲宽度约为50ps,光功率为-3dB对应的谱宽小于0.2nm,输出光波长和功率稳定。此研制的国产化皮秒脉冲激光器模块可满足量子密钥分配系统对光源稳定性的要求。     

A 40-GHz 850-fs regeneratively FM mode-lockedpolarization-maintaining erbium fiber ring laser

An 850-fs pulse train at 40 GHz was directly generated from a regeneratively FM mode-locked fiber laser. The soliton effect was used to generate a short pulse and to suppress the supermode noise. The laser was locked to an external signal by a phase-locked loop (PLL) technique and the wavelength was tunable between 1540 and 1555 mn     

迫弹激光引信用脉冲半导体激光电源的设计与应用

设计了适应于迫弹激光近炸引信的小体积、低电压、窄脉宽、高功率的脉冲半导体激光电源.采用电容充放电的模式,选用高速大功率MOSFET管作为开关,设计了相应的高速开关控制电路.激光电源模块的重复频率高达50kHz,常规热电池供电电压条件下的输出脉冲激光峰值功率为9W,光脉冲上升沿为4.2 ns,光脉宽为10 ns,为有效提...     

1.06μm注入锁定增益开关半导体激光器特性分析与功率放大研究

报道了1.06 m增益开关半导体激光器的详细特性分析和功率放大研究。用高频正弦信号调制中心波长1.06 m的F-P腔半导体激光器得到脉宽约为100 ps、平均功率约为20 mW,重频从500 MHz到2 GHz连续可调的稳定短脉冲激光输出。采用注入锁定改善增益开关半导体激光器的输出特性。研究和分析了调制信号的频率、功率和偏置电流的大小以及注入锁定的功率、温度对激光器输出特性的影响。将该激光器作为种子,用108 W的抽运光进行两级全光纤功率放大得到了82 W的高功率输出,光光转换效率达到76%。     

Measurements of mode partition noise of laser diodes

Mode partition noise may become the dominant performance limitation for single-mode fiber systems. We define the mode partition coefficientkfor laser diodes which can be used as a universal index, like threshold current and spectral width, to characterize laser diodes. Thekvalue varies between 1 and 0, and for largerk, the mode partition noise will be higher. We also demonstrate two simple techniques for measuringk: the low-pass filter method and the sampling method. We discuss thekvalues measured under different operating conditions (pulse width, dc bias) for several types of laser diodes,kvalues are around 0.4-0.6 with short pulse width (1.5-5ns), and decreases to 0.14 pulse width of 50 ns. The largestkvalues were obtained for a laser exhibiting strong relaxation oscillation. For that laser,kdid not depend on the pulse width. Thekvalue is an important factor for system and fiber design as well as laser diode design.     

机载脉冲式激光测距机接收电路的设计

采用硅雪崩管作为光电传感器,将光背景噪声或被测目标漫反射激光转变为微弱电压脉冲,经过两级低噪声可变增益放大器AD603放大后,信号变为幅度较大的电压脉冲,由可编程逻辑器件处理器在单位时间内收集脉冲个数,通过D/A转换电路驱动高压模块改变APD的偏压,最终设计出机载脉冲式激光测距机灵敏度高的闭环负反馈微弱激光接收电路     

LD泵浦Nd:YVO4／SESAM锁模激光器实验研究

报道了利用LD泵浦Nd∶YVO4激光器,用半导体可饱和吸收镜(SESAM)做被动锁模元件,实现了高效的连续锁模运转,输入功率7.5W时得到2.45W的激光输出,光-光转换效率达32.7%,锁模脉冲的重复频率为108MHz.     

Rapid beam scanning using a mode-locked laser-driven laser array

A scheme for driving a laser-array with the spatially dispersed spectral components of a mode-locked laser to achieve very rapid (⩽1 ns) beam scanning is outlined. In the proposed scheme, the precisely-timed periodic pulse train generated by a mode-locked picosecond laser is used as the injection-locking source for the separate lasers of an uncoupled laser array. In a mode-locked picosecond laser, the time-varying gain or loss in the laser cavity forces the oscillating modes to be precisely equally-spaced spectrally and exactly phase-locked leading to a train of precisely-timed periodic short pulses in the output. The corresponding equally-spaced and phase-locked CW spectral components of a single mode-locked laser can be used as a source for locking the individual lasers oscillating in the fundamental spatial modes in an uncoupled laser-array for beam-scanning. The schematic of a conceptual proposal of such a system is presented, and the practical implementation of such a mode-locked-laser-driven laser array is considered     

激光二极管抽运掺Yb3+光纤放大器获得2.41W超短脉冲输出

对国产掺镱(Yb3 )双包层大模场面积光纤超短脉冲放大器进行了系统的实验研究。以自己搭建的脉冲宽度为2.3ps,重复频率为95MHz的全固态锁模激光器作为种子源,以976nm大功率光纤耦合激光二极管为抽运源,以1.6m国产掺Yb3 双包层大模场面积光纤为增益介质,在11.2W的入纤抽运功率下,将平均功率为100mW的脉冲种子光放大到平均功率2.41W,单脉冲能量达到了25nJ,放大后脉冲的宽度(时域宽度)和光谱都有所展宽。     

The Study on the Variation of the Cavity Length''''s Influence on the Output Pulse Train of the Actively Mode-Locked Fiber Laser

1 Introduction The actively mode-locked fiber laser is a very poten-tially valuable light source applied to ultrafast OpticalTi me Division Multiplexed ( OTDM) communicationsystems,optoelectronic sampling systems ,etc .,for itcan generate very short (the duration of the pulseisjustseveral ps or evenless) ,highrepetition-rate (the repeti-tion-rate can be 40 GHz or more) optical pulse train.However ,fiber ringlasers are very sensitive to environ-mental perturbations such as temperature fluct…