2 μm固体激光器的注入锁定

为了获得满足2 μm相干多普勒激光雷达使用的激光光源,进行了注入锁定固体激光器的实验研究。种子激光器采用双端镀腔膜的Tm,Ho:YLF微片晶体,在低温液氮环境下,获得单纵模稳频激光输出。从激光器采用有利于单纵模运转的环形腔结构,并利用熔融石英声光调Q获得脉冲输出。通过注入锁定,实验获得激光输出波长为2.067 μm,在重复频率大于20 Hz时,激光器的最终单脉冲输出能量2 mJ,脉冲宽度为146 ns。实验论证了注入锁定系统激光器作为雷达光源的可行性,并理论分析了种子注入时环形腔内的初始光场分布。     

固体相干激光雷达多普勒测速实验

采用单块非平面环形激光器作为种子,注入到单纵模运转的Q开关高重复频率Nd:YAG激光器为发射源,同时运用温度反馈控制,使种子光源和从动激光器自由振荡频率相匹配,实现稳定的单频输出.采用外差式相干探测的方法,测量运动目标的多普勒频移,从而达到测量运动物体速度信息的目的.根据实验现象,分析失谐频率△ω对外差探测的影响,提出了改进措施并应用于实验.比较已观测到的实验数据与理论计算值分析误差来源.     

Tm,Ho:YAP种子注入激光多普勒测速实验

报道了一台二极管泵浦种子注入Tm,Ho:YAP激光器。在重复频率100 Hz时,获得了单脉冲能量2.8 mJ、脉冲宽度289 ns的2.13 m单频脉冲激光输出。利用该种子注入Tm,Ho:YAP激光器作为发射光源,以一个最大标称线速度20.4 m/s、直径10 cm的风扇作为模拟探测目标,通过外差式相干探测的方法进行了激光多普勒测速实验。利用本振光与信号光的激光拍频信号,得到包含模拟探测目标速度信息的多普勒频移,通过数据处理计算出了风扇不同转速条件下模拟探测目标的速度,并与模拟目标的实际速度进行了比对,测量速度误差小于1 m/s。     

铁共振荧光多普勒激光雷达光源的频率稳定性研究EI北大核心CSCD

种子注入的372 nm稳频Nd:YAG激光器作为铁共振荧光多普勒激光雷达的激光光源,其性能将直接影响大气温度和径向风速的测量精度,属于研制难度较大但极其重要的关键技术。文中对激光光源的频率稳定性进行了仿真分析和实验研究。利用蒙特卡洛方法,仿真了振荡级输出1116 nm脉冲光的频率稳定性(均方根)应小于1 MHz;对改进型Ramp-Fire种子注入技术进行了详细介绍,并在振荡级光路中采用了该技术;通过激光拍频实验,测量得出1116 nm脉冲光在10 min内的频率稳定性的均方根为543.24 kHz,其结果满足指标要求,可将频率抖动和频率漂移引起的系统误差减少至0.51 K和0.61 m/s。文中所做工作为铁共振荧光多普勒激光雷达实现大气温度和径向风速的高精度测量提供了必要保障。     

相干多普勒测风激光雷达研究

研制了一套用于大气风速测量的1.064 μm全固态相干激光雷达系统。该系统采用种子注入 Nd∶YAG脉冲单频激光器作为光源。激光的脉冲能量为0.5 mJ,脉冲宽度(FWHM)为80 ns。 利用40 m处的转轮进行了硬靶速度校正实验(速度测量误差的方差为0.23 m/s),并对大气视向风速进行了测量(探测距离可 到达400 m)。在对系统进行初步优化后,获得了30 ～ 870 m的视向风速分布曲线。     

种子注入光学参量振荡器的纵模特性研究

主要对种子注入单纵模光学参量振荡器的纵模特性进行了理论和实验研究。利用数值模拟方法,对光参量振荡器中的场强方程进行了求解,得出在种子注入情况下,单纵模脉冲光参量振荡器的输出光频率主要由谐振腔纵模频率决定,而注入光频率与腔纵模频率的偏差应小于腔纵模间隔。并利用多纵模的Ｈｅ－Ｎｅ激光器作为种子光,成功地获得了单纵模参量光输出     

实现2 μm固体激光器的注入锁定

2μm固体激光器具有处于人眼安全波段和较低的大气消光比等优点,已成为固体激光雷达的首选光源.将输出单纵模、窄线宽、频率稳定的种子激光注入到环形腔中进行放大,可以获得满足激光雷达使用的激光光源.我们使用双端镀膜的Tm,Ho∶YLF微片作为种子激光器,在低温条件下,获得15 mW     

基于铷原子调制转移光谱技术的1560nm光纤激光器频率锁定研究

1560 nm窄线宽激光器作为光学C波段的重要波长成分,在光纤传感和激光雷达等领域有着广泛的应用,实现该波段的激光稳频对光谱学和精密测量具有重要意义。本文采用1560 nm窄线宽光纤激光器作为种子光源,倍频至780 nm波段后,利用调制转移光谱（MTS）将倍频光锁定在铷原子(⁸⁵Rb)D2线的3-4交叉峰上;并研究探测光和泵浦光功率比、调制解调信号的频率和幅值来优化MTS信号,最终同时实现1560 nm光纤激光器的频率锁定及780 nm的稳频输出。激光器稳频后与低噪声精密锁定的光学频率梳进行拍频,通过频率计测量拍频信号并进行Allan方差分析,积分时间为10 s时,相对频率稳定度为1.4×10^-11。     

单频脉冲激光器的分子吸收光谱频率稳定技术研究

单频脉冲激光器的频率稳定性显著地影响直接探测多普勒激光雷达的风速测量准确性,工作在半导体抽运Nd…YAG激光器倍频532nm的种子注入脉冲激光器的典型自由频率漂移可达15MHz/min,相当于4m/s风速误差。基于碘分子吸收光谱稳频原理,采用Labview虚拟仪器控制技术,对种子注入脉冲放大式的半导体抽运Nd…YAG激光器进行稳频,实现了脉冲激光器的频率扫描、碘分子1109光谱吸收线的自动匹配和频率锁定。长时间(大于2h)频率漂移标准偏差为0.8MHz,等效风速误差为0.2m/s,达到直接探测多普勒测风激光雷达长时间测量对脉冲激光器的频率稳定要求。     

百纳秒脉宽单频大能量1064 nm激光器

报道了基于光纤-固体混合放大的百纳秒脉冲宽度单频大能量1064 nm激光光源的研究工作。采用1064 nm分布反馈(DFB)半导体激光器作为单频连续种子光光源,采用声光调制器将种子光整形为脉冲宽度约为149.0 ns的洛伦兹波形脉冲光,重复频率为60 Hz,经过级联的全保偏光纤放大器放大后,获得单脉冲能量约为2.1μJ、脉冲宽度约为216.7 ns的脉冲光输出。固体放大部分采用激光二极管(LD)端面抽运的Nd∶YVO₄晶体作为高增益的前放大器进行双程放大,采用LD单侧面抽运的Nd∶YAG板条晶体作为预放大器进行双程放大,采用两级LD双侧面抽运的Nd∶YAG板条晶体作为功率放大器,最终获得了单脉冲能量为151.4 mJ、脉冲宽度约为267.8 ns的激光输出。采用光学外差法对输出脉冲激光的线宽进行了测试,线宽约为14.2 MHz。研究结果为星载相干测风激光雷达采用1.06μm的激光光源提供了新的技术路线。     

单纵模激光的再生放大

调Ｑ激光器的输出单纵模脉冲经衰减和削波后，被注入到一Ｎｄ∶ＹＬＦ调Ｑ副腔里，注入脉冲能量１．２ｎＪ，放大以后的脉冲能量１．５ｍＪ，增益达１０６；脉宽由６ｎｓ压缩到４．５ｎｓ。实验和理论分析均表明，当注入信号脉宽短于放大器腔来回一周的时间时，副腔对单纵模激光的放大是一种再生放大行为，单纵模激光的再生放大消除了注入锁定中苛刻的腔长匹配要求。     

全固态被动调Q单频绿光激光器的研究

报道了一种LD近贴泵浦、KTp晶体腔内倍频的NdYVO4/CrYAG/KTP结构高重复频率被动调Q绿光激光器.当腔内加入布氏片时,获得了单频运转.在注入泵浦功率为800mW时,得到平均功率43 mW、脉冲宽度26.4 ns、重复频率39.3 kHz、峰值功率41.4 W的被动调Q单频脉冲绿激光输出.     

可调谐单频非平面环形腔固体激光器

研究了单块晶体成腔的单频非平面环形腔(NPRO)固体激光器,在1.83W的808nm抽运功率下输出激光1.01W,斜率效率达到60%。采用拍频的方法对激光线宽进行了测试,激光线宽小于2kHz。通过抽运电流反馈控制使弛豫振荡峰得到超过30dB的抑制;通过对激光晶体的温度调节和压电陶瓷电压调节实现了激光器频率的慢调谐和快调谐,温度慢调谐变化10℃时激光频率变化范围超过15GHz;压电陶瓷快调谐范围超过±200MHz,在大于200MHz的范围内响应时间达到45μs。     

用注入锁模法改善DFB激光器的频率响应

验证了通过注入锁模方法,分布反馈(DFB)半导体激光器的频率响应可以得到明显的改善.实验中通过一个环形器,将主激光器的输出光注入到从激光器.测量了从激光器在有注入光和没有注入光时的光谱和频率响应.发现在不同的注入光强度和波长下,激光器的调制带宽和弛豫振荡峰频率会发生变化.通过适当选择注入光的强度和波长,频率响应可以得到改善.激光器频率响应的改善可以用两个模式的拍频来解释,一个模式是从激光器的主模,另一个是主激光器的模式,该模式与从激光器的边带重合.该理论与实验结果符合得很好.     

A synthesized method to improve coherence in semiconductor lasersby electrical feedback

A method for improving coherence in semiconductor lasers by negative electrical feedback is proposed for stabilization of the center frequency of the field spectrum, linewidth reduction of the field spectrum, frequency tracking to another highly coherent laser, and stable and wideband frequency sweep. Experimental center frequency stabilization of the master laser showed that the magnitude of frequency fluctuations was reduced to 50 kHz at the integration time τ=3 s. The linewidth of the master laser was reduced to 100 kHz, which was 1/50 that of the free running laser. Under these frequency control conditions, the frequency of the slave laser was controlled so that the phase of the heterodyne signal between the master and the slave lasers could be locked to that of a stable microwave synthesizer. The slave laser frequency tracked accurately to the master laser frequency     

单纵模被动调Q脉冲激光频率稳定性研究

采用脉冲波形观察、干涉条纹成像和角度光强扫描3种方法相结合,设计并建立了进行单纵模(SLM)被动调Q脉冲激光频率稳定性测量的实验装置,同步获得光滑的脉冲波形、面阵CCD上的多光束干涉图像和角度扫描F-P标准具的激光透射强度曲线,通过比对分析实验结果表明,该脉冲激光的长期频率稳定性为10-7量级。     

Microwave signals generated by optical heterodyne betweeninjection-locked semiconductor lasers

Single-mode-laser rate equations with added Langevin noise sources are used to study injection-locked semiconductor lasers. Two slave lasers are frequency-locked on the same or different sidebands of a current-modulated master laser. The optical heterodyne between the two secondary lasers is characterized. It is demonstrated that the frequency stability of the source modulating the master laser is preserved on the sidebands and partially transferred to the slaves. A linear model is first investigated. Static operation conditions and small-signal behavior are then calculated. Direct simulation of the rate equations for each laser is next achieved. This highlights the validity domain and limitations of the linear model. A more complete set of results-such as laser and heterodyne spectra-is also obtained. It is moreover shown that synchronization of the slave laser diodes by optical injection-locking leads to strongly correlated, while not identical, laser fields. Finally, simulation results are compared to experimental data     

用布氏片实现有效连续和脉冲单频绿光输出

通过对布氏片实现选频的理论分析,采用腔内插入双布氏片和布氏片与Q开关相结合的方法,分别实现了较大功率单频绿光的连续和脉冲稳定输出。在注入抽运功率为1.3W时,连续单频输出平均功率达到124mW,脉冲单频输出峰值功率达到108W。     

Amplitude-modulation sideband injection locking characteristics ofsemiconductor lasers and their application

Amplitude-modulation (AM) sideband injection-locking characteristics of 1.3-μm distributed-feedback lasers are studied experimentally. When the master laser light, which is amplitude-modulated, is injected into slave lasers, the slave lasers can be phase-locked to each sideband of the master laser. This means that the frequency separation between slave lasers can be controlled by the modulation frequency of the master laser. By controlling the injection power, it is possible to achieve a very stable AM sideband injection-locked state of slave lasers. Results on phase-noise and phase-modulation measurements, the frequency stabilization between two channels, and the injection locking to a short pulse are presented. On the basis of the experimental results, an example for designing the multifrequency laser transmitter by means of the AM sideband injection-locking and the mode-locking techniques is described     

Diode-pumped single-frequency Tm:YAG NPRO laser by using different pumping spot sizes

This paper presents the experimental results of the monolithic Tm:YAG nonplanar ring oscillator (NPRO) pumped by two kinds of laser diodes with different pumping spot sizes. By longitudinal pumping in continuous-wave operation, a single-frequency output power of 404 mW was obtained at room temperature,with a slope efficiency of 48.2%. The influences of the pumping spot sizes on the beam properties were also discussed.