全固态窄线宽钠导星激光器

研制了一台重复频率400 Hz,平均功率1.0 W的激光二极管抽运全固态窄线宽钠导星激光器.利用两路波长分别为1064 nm和1319 nm的声光(AO)调Q激光器作为基频光,在腔外通过三硼酸锂(LBO)晶体和频产生(SFG)589 nm钠导旱激光,和频效率约达20%.每路基频光均采用标准具压窄线宽,输出和频光线宽约1.8 GHz,并调节控制标准具的温度和倾斜角度将中心波长锁定于589.159 nm(偏差±1 pm),实现了激光器谱线与钠原子D2线的精确匹配.     

双光梳重复频率差异步锁定技术研究

双光梳系统在高精度绝对距离测量、三维成像以及光谱测量等领域有着其独特的优势和广阔的发展前景。文中提出一种基于锁相环原理的异步锁定技术，可以对双光梳系统中的重复频率差进行精密锁定。实验中，采用了重复频率约为155.711 MHz和155.714 MHz的双光梳系统，通过反馈控制压电陶瓷（PZT）驱动电压从而控制激光器谐振腔腔长来实现重复频率差的锁定，并利用频率计数器采集锁定后双光梳重复频率差的数据，使用Allan方差和标准差作为频率稳定度的评价指标。最终在1 s的平均时间内，得到重复频率差的Allan偏差为1.8×10?13，抖动标准差为40.689 μHz。结果表明，该技术可以对双光梳系统的重复频率差进行灵活调整，并具有锁定精度高、抗扰能力强等优点。     

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。     

两台独立飞秒激光器的脉冲序列与载波包络相位同步

研究了两台独立运转的掺镱光纤飞秒激光器的脉冲序列与载波包络相位同步。使用平衡光学互相关的方法探测两台激光器的脉冲延迟,控制腔内高速压电陶瓷以锁定两台激光器的重复频率,得到两台激光器的剩余相对时间抖动为380as。不同的重复频率锁定带宽会对载波包络相位信号产生明显的影响,相比于使用压电陶瓷(低锁定带宽),使用电光调制器锁定重复频率(高锁定带宽)会使载波包络相位产生额外的噪声。将两台激光器的输出脉冲在空间上重合,入射进入平衡探测器,探测到两台激光器的相对载波包络频率信号。使用腔外声光调制器对两台激光器的载波包络相位进行锁定,得到两台激光器的剩余相位噪声为495mrad。锁定后观测到两激光器的光谱干涉,为相干脉冲合成奠定基础。     

全保偏掺铒光纤光梳

搭建了基于非线性放大环形镜的全保偏掺铒光纤激光器,它可为光梳系统在室外环境中的应用提供稳定运行的光学振荡源。在实验上,通过两级光学预放大及高非线性光纤获得了1000~2300 nm的超连续谱,采用共线型f-2f干涉仪检测到的载波包络偏移频率f0的信噪比高达35 dB。研究了腔内净色散和f0线宽的关系,并将自由运转状态下的f0线宽窄化至5 kHz。将光梳系统的主要参数(重复频率fr和载波包络偏移频率f0)溯源至同一台铷原子钟,锁定后所测标准偏差分别为780μHz和308 mHz。该光纤光梳系统具有集成度高、体积小的特点。     

采用NPRO光源的零差相干光通信实验

在空间相干光通信应用中,针对传统激光器线宽较宽、相位噪声大、易导致锁相环路失锁的问题,研制了单频Nd:YAG非平面环形（NPRO）激光器,其线宽小于1 kHz,相对强度噪声（RIN）低于-150 dB/Hz,具有窄线宽、低噪声的特点。搭建了光锁相环路,在信号光功率-67 dBm的情况下实现了两台NPRO激光器的相位锁定。在此基础上开展了信号频率为10 MHz和1.25 GHz的模拟通信实验,在信号光功率分别为-60 dBm和-53 dBm时可观测到较理想的眼图。在2.5 Gbps数字通信实验中,接收灵敏度达到-50 dBm,此时误码率为3.210-6。系统灵敏度可接近量子极限,明显优于传统的IM/DD方式,是一种适合长距离、大容量传输的空间通信方式。     

单端光纤耦合的声光调Q全光纤化光纤激光器

实现了一种单端光纤耦合的高重复频率、窄脉冲、窄线宽及高效率的主动声光调Q全光纤脉冲光纤激光器。该光纤激光器基于光纤光栅与平面镜组合而成的线性法布里-珀罗(F-P)腔结构,采用激光二极管与(2+1)×1抽运耦合器形成后向抽运,并利用单端光纤耦合声光调制器(AOM)实现了全光纤化结构的脉冲掺镱双包层光纤激光器。调Q声光开关工作在一级方向,反向输出调Q脉冲,重复频率20～100kHz可调。在重复频率50kHz、抽运功率5.7W下系统获得了输出激光功率2.64W、单脉冲能量528μJ、脉宽56ns、峰值功率943W的稳定的高效率、窄线宽的窄脉冲,中心波长在1080nm左右,线宽为0.06nm,光-光转换效率高达46%。     

基于复合双环腔及饱和吸收体的单纵模窄线宽掺铥光纤激光器

提出并实现了一种工作在2050 nm波段的单纵模窄线宽掺铥光纤激光器。使用3个耦合器组成的新型复合双环腔抑制密集的多纵模,结合未泵浦的掺铥光纤（作为饱和吸收体）,实现了激光的单纵模激射和窄线宽输出。实验结果表明：室温下,激光器的中心波长为2048.76 nm,光信噪比为68 dB。通过60 min的连续测量,得到激光的输出功率波动不大于0.15 dB,中心波长漂移不大于0.02 nm,证明了所设计的激光器具有良好的波长稳定性和功率稳定性。使用基于3×3光纤耦合器的相位解调系统对激光器的频率噪声特性进行测量,并进一步结合β分割线法测量线宽。当测量时间为0.001 s时,激光器的线宽为9.17 kHz。当频率高于1 MHz时,相对强度噪声低于-125.69 dB/Hz。该激光器在激光雷达和空间光通信系统中具有广阔的应用前景。     

YAG激光器泵浦钛宝石激光器和光学参量振荡器

采用一台调Q脉冲式Nd：YAG激光器同时泵浦Ti：蓝宝石激光器和光学参量振荡器（OPO），在重复频率30Hz下获得了Ti：蓝宝石可调谐激光波长为700～890nm，转换效率28．8％及440～2600nm的连续可调谐窄线宽的光参量激光输出，能量转换效率达23％。     

注入锁定光纤环形腔激光器实验研究

利用注入锁定技术,将中心频率稳定、窄线宽的DFBLD作为主激光器,将光纤环形腔激光器作为从激光器。在实现注入锁定后,利用光纤环形腔谐振特性,在效压窄了注入光线宽。得到了中心频率稳定,较之DFBLD线宽更窄的输出激光,目前线宽已被压窄到70kHz。     

High-performance phase locking of wide linewidth semiconductorlasers by combined use of optical injection locking and opticalphase-lock loop

The requirement for narrow linewidth lasers or short-loop propagation delay makes the realization of optical phase-lock loops using semiconductor lasers difficult. Although optical injection locking can provide low phase error variance for wide linewidth lasers, the locking range is restricted by stability considerations. Theoretical and experimental results for a system which combines both techniques so as to overcome these limitations, the optical injection phase-lock loop (OIPLL), are reported. Phase error variance values as low as 0.006 rad ² (500 MHz bandwidth) and locking ranges exceeding 26 GHz were achieved in homodyne OIPLL systems using DFB lasers of summed linewidth 36 MHz, loop propagation delay of 15 ns and injection ratio less than -30 dB. Phase error variance values as low as 0.003 rad² in a bandwidth of 100 MHz, a mean time to cycle slip of 3×10¹⁰ s and SSB noise density of -94 dBc/Hz at 10 kHz offset were obtained for the same lasers in an heterodyne OIPLL configuration with loop propagation delay of 20 ns and injection ratio of -30 dB     

波长可切换窄线宽单频掺镱光纤激光器（特邀）

基于光纤环形激光器,设计出由三端口环形器、偏振控制器、未泵浦保偏掺镱光纤和光纤布拉格光栅组成的滤波器件作为高精度滤波器对谐振腔内的模式个数进行抑制,通过调谐偏振控制器,在保偏掺镱光纤内形成的梳状光谱和动态光栅,实现了窄线宽、单、双波长可切换单频掺镱光纤激光器。单波长运行时,在1064.37 nm处测得激光器输出线宽346 Hz,光信噪比大于50 dB,30 min内该激光器波长及功率的不稳定性均在0.01 nm和0.2 dB范围内。通过调节偏振控制器,单波长和双波长可以实现互相切换,双波长分别位于1064.156 nm和1065.236 nm。该技术为超窄线宽激光器的双波长输出提供了新的途径。     

A Monolithic MQW InP–InGaAsP-Based Optical Comb Generator

We report the first demonstration of a monolithic optical-frequency comb generator. The device is based on multisection quaternary/quaternary eight-quantum-well InP-InGaAsP material in a frequency-modulated (FM) laser design. The modulation is generated using quantum-confined Stark-effect phase-induced refractive index modulation to achieve fast modulation up to 24.4 GHz. The laser was fabricated using a single epitaxial growth step and quantum-well intermixing to realize low-loss phase adjustment and modulation sections. The output was quasicontinuous wave with intensity modulation at less than 20% for a total output power of 2 mW. The linewidth of each line was limited by the linewidth of the free running laser at an optimum of 25 MHz full-width at half-maximum. The comb generator produces a number of lines with a spacing exactly equal to the modulation frequency (or a multiple of it), differential phase noise between adjacent lines of -82 dBc/Hz at 1-kHz offset (modulation source-limited), and a potential comb spectrum width of up to 2 THz (15 nm), though the comb spectrum was not continuous across the full span.     

Study on ultra-precision phase synchronization technique employing phase-locked loop

Microwave-to-optical phase synchronization techniques have attracted growing research interests in recent years. Here, we demonstrate tight, real-time phase synchronization of an optical frequency comb to a rubidium atomic clock. A detailed mathematical model of the phase locking system is developed to optimize its built-in parameters. Based on the model, we fabricate a phase locking circuit with high integration. Once synchronized, the fractional frequency instability of the repetition rate agrees to 6.35×10^-12 at 1 s and the standard deviation is 1.5 mHz, which indicates the phase synchronization system can implement high-precision stabilization. This integrated stable laser comb should enable a wide range of applications beyond the laboratory.     

Wide-span optical frequency comb generator for accurate opticalfrequency difference measurement

An optical frequency comb (OFC) generator was realized for accurate optical frequency difference measurement of 1.5 μm wavelength semiconductor lasers by using a high frequency LiNbO₃ electrooptic phase modulator which was installed in a Fabry-Perot cavity. It was confirmed that the span of the OFC was wider than 4 THz. By using semiconductor lasers whose spectrum linewidths were narrowed to 1 kHz and a sensitive optical balanced-mixer-receiver for measuring beat signal between the sideband of the comb and the laser, we demonstrated a frequency difference measurement up to 0.5 THz with a signal-to-noise ratio higher than 61 dB, and a heterodyne optical phase locking with a heterodyne frequency of 0.5 THz in which the residual phase error variance was less than 0.01 rad². The maximum measurable frequency difference, which was defined as the sideband frequency with the signal-to-noise ratio of 0 dB, was estimated to be 4 THz     

Phase noise reduction by self-phase locking in semiconductor lasersusing phase conjugate feedback

A theoretical analysis of the behavior of the frequency/phase noise of semiconductor lasers with external phase conjugate feedback is presented. It is shown that the frequency noise is drastically reduced even for lasers with butt-coupled phase conjugate mirrors. In this laser system, the phase noise takes a finite-low value corresponding to a state of first-order self-phase locking of the laser. As a result, the spectral shape of the laser signal does not remain Lorentzian but collapses around the carrier to a delta function with a close to carrier noise level of less than -137 dBc/Hz. The total phase variance of this laser signal, in a 20 GHz noise bandwidth, is less than 0.002 rad²      

基于固定频率激光器的低成本闭环谐振陀螺系统仿真

提出了一种使用固定频率窄线宽激光器作为干涉光源的闭环谐振式光纤陀螺系统.该系统利用相位调制器对干涉光进行移频控制,完成对谐振腔逆时针方向谐振频率的跟踪和锁定.建立了陀螺系统Simulink模型并仿真研究了不同速率点下的陀螺输出特性,结果表明,±200(°)/s速率范围内逆时针谐振频率锁定时间小于15 ms,陀螺标度因数非线性为2.41×10-4.与采用传统频率可调谐窄线宽激光器的闭环谐振式光纤陀螺系统相比,两者锁频时间和标度因数非线性基本一致.该研究为低成本闭环谐振式光纤陀螺系统的实现提供了理论和数据支撑.