光纤光栅外腔半导体激光器频率调谐技术研究

在分析了光纤光栅外腔半导体激光器(FBG-ECL)基本特性的基础上,调研了适用于该类型激光器的频率调谐方法,包括温度调谐法和应力调谐法,选取轴向应力调谐法改变光纤光栅的布拉格中心波长,进而实现频率调谐。利用压电陶瓷(PZT)来对光纤光栅施加轴向应力,通过调整PZT驱动电压值的大小来控制光纤光栅布拉格中心波长的变化量。实验结果表明,对于波长1550 nm的光纤光栅激光器,当PZT的驱动电压增加到126 V时,可实现 0.8 nm,即100 GHz的调谐范围以及每周期2 ms的调谐速度。     

非平面环形激光器的大范围调谐技术研究

为了实现窄线宽非平面环形Nd:YAG激光器的大范围压电和温度调谐,采用对粘接在激光晶体上的薄压电陶瓷片施加高压驱动信号,并大范围控制激光晶体温度的方法,获得压电调谐范围达到210MHz,调谐带宽大于90kHz,压电调谐系数大于1MHz/V;当控制激光晶体温度在10℃到47℃范围内变化时,输出激光在8GHz范围内可连续调谐,总的调谐范围达到61GHz。结果表明,高频压电调谐时拍频展宽形状发生改变的主要原因是压电驱动信号失真。结合压电调谐和温度调谐的各自优点,激光频率调谐实验取得了良好效果。     

利用单边带调制器实现对多波长光纤激光器的高精度射频控制调谐技术

提出了一种利用射频控制信号对多波长光纤激光器输出的多波长信号进行整体精密调谐的方法。通过在多波长光纤激光器腔外放置射频信号控制的单边带(SSB)调制器,实现了65个波长整体精密调谐。通过改变射频驱动信号频率,可以实现多波长整体在150MHz~12GHz范围内的任意调谐,最低对应1.2pm的调谐量。且调谐步长由射频控制信号决定,可精确到1Hz。多波长整体调谐前后,多波长间隔始终保持50GHz不变,各波长的边模抑制比(SMSR)均可达到20dB。     

基于石英玻璃掺铥光纤的单纵模DBR光纤激光器的研制

研制了一种具有频率调谐功能的2μm波段分布Bragg反射(DBR)型单纵模光纤激光器。该激光器基于石英玻璃单模掺铥光纤和793 nm半导体激光器泵浦源,其光电器件分离集成在1U机箱内。通过内置压电陶瓷(PZT),可实现对激光频率的快速调谐，调谐范围约6 GHz;通过TEC温度控制,可实现对激光频率在29 GHz范围内无跳模调谐。单纵模激光输出功率为18.2 mW,输出激光信噪比大于60 d B,泵浦转换效率达27%。该激光器样机可望在高分辨光谱、量子信息以及非线性频率变换等领域发挥重要作用。     

基于受激布里渊散射的可调谐多波长激光器

可调谐多波长布里渊掺铒光纤激光器将光纤中的SBS非线性放大同掺铒光纤的线性放大相结合得到室温稳定的多波长输出,具有波长间隔一致、线宽窄、功率谱相对平坦等优点。设计了一种基于光纤布拉格(FBG)反射的线性可调谐多波长布里渊掺铒光纤激光器。该线性腔激光器的一端利用光纤布拉格光栅作为反射镜,有效抑制了腔内自激模的影响,增加激光器输出波长数。布里渊泵浦信号进入布里渊增益介质之前经过掺铒光纤放大器的两次放大,降低了布里渊增益的阈值。该多波长激光器实现了1 530～1 560 nm之间30 nm可调谐范围的输出。在布里渊泵浦信号功率2 mW,980 nm泵源抽运功率60 mW情况下,1 540～1 554 nm范围内,获得了波长间隔0.088 nm的16个波长的输出。     

高速率光纤通信系统激光器技术

文章介绍了适用于高速率光纤通信系统的可调谐激光器技术,对比了常见可调谐半导体激光器的技术发展及特点,介绍了目前较为前沿的可调谐光纤激光器技术,指出了可调谐光纤激光器对实现全光网的重要作用和巨大的发展潜力。     

2μm波段DBR光纤激光器的超稳腔PDH稳频技术

报道一种可用于超稳腔Pound-Drever-Hall(PDH)稳频的2μm波段分布Bragg反射（DBR）光纤激光器及其频率锁定结果。该绝热封装的光纤激光器配备主动温度控制和压电陶瓷（PZT）频率调谐装置,可满足超稳腔PDH稳频应用。通过周期极化铌酸锂（PPLN）晶体倍频,采用PDH稳频技术将研制的1950 nm光纤激光器频率稳定到了1μm波段超稳腔频率参考上。针对DBR光纤激光器中PZT频率调谐机制只反馈调节腔长,容易在稳频过程中产生激光器跳模进而导致频率失锁的问题,笔者提出并演示了一种对DBR光纤谐振腔实施基于超稳腔频率参考的实时温度控制方案,并采用该方案实现了对DBR光纤激光器超过4周的长期频率锁定。该方案对于实现DBR光纤激光器的长期频率锁定具有较高的参考价值。     

一种基于FBG宽调谐的复合环形腔单纵模光纤激光器

报道了一种宽调谐单纵模光纤激光器。该光纤激光器采用环行器确保腔内激光的单向传输,可以有效消除空间烧孔效应;采用复合腔的Vernier效应选取单个纵模;利用未泵浦掺杂光纤的可饱和吸收效应,有效抑制光纤激光器的跳模现象;同时,利用自行研制的光纤光栅调谐装置,调谐激光器振荡波长。测试结果表明,该单纵模光纤激光器输出激光的线宽为0.7KHz,功率为10mW,波长调谐范围为20nm,且调谐过程中始终保持单纵模特性。     

基于空心光子晶体光纤谐振腔的激光器频率调谐系数测试

针对激光器频率调谐系数测试应用的需求,提出了基于空心光子晶体光纤的激光器频率调谐系数测试装置的方案。首先,对测试装置的总体方案、光子晶体光纤谐振腔的基本结构进行设计,重点完成了激光器频率调谐系数测试方法的数值计算和机理分析;之后,完成了光子晶体光纤谐振腔的设计和加工,并搭建了激光器频率调谐系数测试装置;最后,对目前常用的窄线宽光纤激光器和半导体激光器进行频率调谐系数测试。光纤激光器的电压-频率调谐系数为17.6 MHz/V,与激光器出厂指标基本吻合,而且光纤激光器的频率调谐系数在调谐范围内具有良好的一致性。半导体激光器在调谐范围内的调谐系数不均匀,容易受环境的影响,测得电流-频率调谐系数的平均值为30.9 MHz/mA。研究结果表明,测试装置的精度远高于商用波长计,并且具有良好的长期稳定性,充分体现出了空心光子晶体光纤谐振腔作为频率基准进行频率检测所具有的测频精度高、温度漂移小的技术优势。     

环行腔掺铒光纤激光器调谐实验研究

本文自行设计环行腔可调谐光纤激光器,研究环行腔掺饵光纤激光器的调谐技术,采用应力可调谐光栅进行实验,解决了光纤激光器普遍存在的泵浦光反射形成的回波影响问题和窄线宽激光输出功率与激光模式的矛盾,讨论了输出耦合比对调谐特性的影响,实现了窄带滤波和宽带调谐的双重特性,实现了窄线宽可调谐激光输出。     

Electrically Tunable Microwave Generation Using Compact Dual-Polarization Fiber Laser

A simple technique for tunable microwave frequency generation based on a compact dual-polarization fiber grating laser incorporated with a piezoelectric transducer (PZT) is demonstrated. The PZT exerts a transversal force to the fiber grating laser which changes the fiber birefringence and, therefore, the wavelength separation between the two polarization lines. The beat tone frequency changes linearly in response to the driving voltage applied to the PZT.      

光纤光栅主动稳频的短直线腔单频光纤激光器

利用1.8cm长的Er3+/Yb3+共掺磷酸盐玻璃光纤作为增益介质制作了一个可调谐的短直线腔窄线宽单偏振单纵模光纤激光器。其谐振腔反射镜由高反射率的光纤布拉格光栅(FBG)和低反射率的保偏光纤FBG构成,使用976nm单模半导体激光器作为抽运源。当进入谐振腔的抽运功率为360mW时获得了输出功率65mW,信噪比大于70dB,线宽约为3kHz,偏振消光比达到40dB的激光输出。另外,通过使用压电陶瓷(PZT)调节增益光纤的长度实现了激光波长的电调谐,其调谐斜率约为14.2 MHz/V。采用边频锁定的方式进行主动稳频,使得激光输出的长期频率波动从25MHz/10s减少到了2.5MHz/h,从而实现了全光纤结构的高功率、高频率稳定性的单频光纤激光器。     

Inherent temperature compensation of a dual-mode fiber voltagesensor with coherence-tuned interrogation

We investigate the effects of temperature on a optical fiber voltage sensor. The sensor is based on the converse piezoelectric effect of quartz. The piezoelectric deformation of the cylinder-shaped transducer crystal induced by an applied at voltage is sensed by an elliptical-core dual-mode fiber. The resulting modulation of the differential phase of the LP₀₁ and even LP₁₁ modes of the fiber is remotely detected by coherence-tuned interrogation using a 780-nm multimode laser diode source. A second dual-mode fiber acts as a receiver interferometer. We determine the influence of temperature on the scale factor of the transducer and on the accuracy of the interferometric interrogation. We further show that the sensitivity to temperature of the group index difference of the sensor fiber modes can be exploited to temperature-correct the scale factor of the transducer     

Tunable Q-switched/cavity-dumped Z-fold CO/sub 2/ waveguide laser with two channels and common electrodes

A tunable Q-switched/cavity-dumped z-fold CO/sub 2/ waveguide laser with two channels and common electrodes is studied. The Q-switched and cavity-dumped pulse lasers have been obtained from the z-fold channel with the tunable pulse repetition frequency (PRF) of 1-70 kHz. At the Q-switched operation, the peak power is 730 W and the pulsewidth is 150 ns at the PRF of 10 KHz. At the cavity-dumped operation, the pulse laser width can be adjusted. The peak power is 6000 W with the pulsewidth of 20 ns and 3400 W for 32 ns. CW laser output has been obtained from the other channel and its frequency can be tuned by a piezoelectric transducer. The Q-switched and cavity-dumped pulse laser heterodyne waveforms are observed.     

Time-Division Multiplexing Fiber Grating Sensor With a Tunable Pulsed Laser

A novel time-division-multiplexing fiber Bragg grating (FBG) sensor with a tunable pulsed laser is proposed and demonstrated. A tunable pulsed fiber laser based on a matched FBG is applied. The wavelengths of the sensing FBGs are obtained by detecting maximum voltages with a photodiode, which avoids a complex demodulation process. The advantages of the sensor include simple structure, high signal-to-noise ratio, and the sensing signals obtained by detecting the maximum voltages     

Fiber Ring Laser Operated by Dynamic Local Phase Shifting of a Chirped Grating

An ultranarrow linewidth erbium-doped fiber ring laser is presented. It is based on the filtering properties of a phase-shifted chirped fiber Bragg grating, which is inserted inside the cavity of the laser. A dynamic control of the phase shifting, which is induced by a magnetostrictive transducer, permits both tunable continuous-wave and actively $Q$-switched operation. The use of a chirped grating overcomes the limitations imposed by the narrow spectra of uniform gratings observed in previously reported ring lasers based on intracavity transmission filters.      

激光参数对激光激发超声信号的影响分析

研究了激光参数对激光激发超声信号的影响.研究中首先理论分析激光激发超声过程中,激光参数对激发超声信号的影响.同时,设计并搭建一种激光激发超声的实验装置,实验验证理论分析结果.该实验装置应用脉冲激光配合光衰减结构对被测目标激发产生超声波,通过超声探头实现激光超声信号的探测.实验中以铝板为检测对象,对激光脉冲能量和照射光斑大小对激发超声信号的影响进行实验分析.通过理论分析及实验验证,可得出照射光斑直径与激光能量会直接影响入射激光功率密度,从而影响激发超声的幅度.     

Finely tunable wavelength conversion of high bit-rate signals byusing a superstructure-grating distributed Bragg reflector laser

Finely tunable wavelength conversion of high bit-rate signals is analyzed numerically and demonstrated experimentally-to a wavelength range from 1530 to 1560 nm-by using a superstructure-grating distributed Bragg reflector laser. Transmission of a 10 Gb/s converted signals over a 100 km-long optical fiber is also demonstrated using a dispersion-shifted optical fiber     

Design and experimental research of a high-precision wavelength controller for tunable fiber Fabry-Perot filters

A high-precision wavelength controller is presented in this paper. It is necessary to find out the difference between the central wavelength of a tunable fiber Fabry-Perot (FFP) filter and that of the input laser, while the wavelength controller operates at the states of wavelength-scanning and wavelength-locking modes. Firstly, a dynamic simulation model of tunable FFP filter is established, and the dynamic characteristic of tunable FFP filter modulated by an alternating current (AC) signal is simulated. Then the measuring time at wavelength-scanning mode compared with the theory time is discussed, and this time difference shows the difference between the central wavelength of a tunable FFP filter and that of the input laser. At last, the effects on wavelength-locking precision of time delays, including the time delay of opened-loop circuit, the time constant of the closed-loop circuit and the intrinsic hysteresis of piezoelectric (PZT) element, are analyzed. A wavelength controller of tunable FFP filter is designed and prepared. The experimental results at wavelength-locking mode show that a high locking precision is obtained.     

All-Fiber Q-Switched Erbium-Doped Fiber Ring Laser Using Phase-Shifted Fiber Bragg Grating

We propose a unique all-fiber Q-switched erbium-doped fiber ring laser. It consists of a phase-shifted fiber Bragg grating (FBG) and an apodized FBG reflector. By using the piezoelectric transducer (PZT) to periodically stretch the apodized FBG and detune it with the phases-shifted FBG, the cavity loss of the fiber ring laser is switched between high and low states to achieve Q-switching. This Q-switched fiber laser has advantages of narrow spectral bandwidth, stable oscillation wavelength, and the repetition rate of the Q-switched pulses can be double of the PZT modulation frequency. A numerical model is developed and presented to simulate and analyze this FBGs-based Q-switched fiber ring laser with consideration of the dynamic response of FBGs during Q-switching. We experimentally demonstrate 10 and 20 kHz Q-switching operation with 10 kHz PZT modulation frequency. The experimental result is similar to the simulation result.