基于特殊子环腔单纵模窄线宽掺铥光纤激光器

提出并实验验证了一种稳定的单纵模窄线宽环形腔掺铥光纤激光器,通过使用特殊的子环腔和自制的光纤布拉格光栅,实现了稳定的单纵模激射和窄线宽输出。子环腔由3个互相连接的光耦合器组成,用来抑制密集的多纵模和跳模。采用自制的光纤布拉格光栅,作为窄线宽波长滤波器,最终实现了稳定的单纵模激射。实验结果表明,该激光器在室温下可获得中心波长为1940.6 nm,光信噪比为60 dB的稳定信号输出。其频率噪声采用基于3×3光耦合器的自零差技术进行测量。当测量时间为0.05 s时,由频率噪声计算的线宽大约为8 kHz。     

基于保偏掺铥光纤饱和吸收体的2μm波段超窄线宽光纤激光器

制作了一种单纵模超窄线宽环形腔掺铥光纤激光器,使用未抽运的保偏掺铥光纤作为饱和吸收体,结合光纤光栅法布里-珀罗滤波器,实现了激光器的单纵模运转和超窄线宽输出。实验结果表明:激光器在室温下可以获得中心波长为1942.03nm、光信噪比为63dB的稳定输出。通过100min的连续测量,激光输出功率的波动小于0.62dB,中心波长的波动小于光谱仪的最小分辨率0.05nm,在一定时间内具有良好的稳定性。采用基于频率噪声的线宽测量方法测得0.01s测量时间下的线宽为300Hz,在0.1s测量时间下的线宽约为3kHz。所制作的激光器将在对2μm波段激光纵模及线宽特性有严格要求的领域具有重要应用价值。     

基于片上微腔自反馈注入锁定的窄线宽激光器

对半导体激光器外腔自反馈注入锁定进行了理论分析,研究了片上微腔的自反馈注入锁定对于分布反馈(DFB)激光器输出线宽的影响,分析了决定锁定带宽及线宽压缩系数的关键参数。基于Q值为2.4×10⁶的片上Si₃N₄微腔的后向瑞利散射实现了DFB激光器的自反馈注入锁定,将其输出线宽由自由运转时的556.71 kHz压窄到了92.28 kHz,锁定带宽达到425 MHz。研究结果有助于理解半导体激光器自反馈注入锁定机理,并为实现窄线宽激光器提供了新的结构更简单、集成化潜力更高的方案。     

一种窄线宽的高重复频率窄脉宽主动调Q光纤激光器

提出并演示了一种基于声光调制器(AOM)主动调Q的环形腔双包层光纤激光器获得窄线宽、窄脉宽和高重复频率激光脉冲的方法。通过在腔内采用以双包层增益光纤作为输入尾纤的泵浦剥离器来缩短腔长,可以降低增益光纤正向放大自发辐射(ASE)的反射,抑制其ASE的增益自饱和效应,使腔内有效增益增大,窄线宽调Q脉冲可在环形腔中快速建立,从而不仅可使调Q脉冲脉宽变窄,还允许其重复频率大幅提升。在7 W泵浦功率下,所提出的调Q光纤激光器获得了线宽和脉宽分别窄至0.16 nm和10.4 ns、重复频率高达150 kHz的调Q激光脉冲。     

窄线宽光纤激光器

为满足传感系统的需求,研制了1 550nm单频窄线宽光纤激光器,采用环形腔结构,利用976nm激光器作为泵浦源,高掺杂掺铒光纤作为增益介质,以低掺杂掺铒光纤作为饱和吸收体,得到稳定的窄线宽激光输出。泵浦功率为200mW时,得到输出功率为21mW,线宽为7.2kHz,波长稳定度为1.26pm,相对强度噪声≤-102dB/Hz1/2。     

一种新型窄线宽掺铒光纤激光器

为了实现稳定的窄线宽激光输出,设计了一种基于有源光纤环形滤波器的窄线宽掺铒光纤激光器,对其系统原理和实验分析进行了讨论。在环形腔中熔接一支分光比为50∶50的2×2熔融拉锥型耦合器,并且通过在该耦合器另外两端熔接一段长2 m的有源光纤,构成有源光纤环形滤波器,实现压窄线宽的目的。实验结果表明,在熔接环形滤波器后,输出激光边模得到明显抑制;在0~400 MHz频谱范围内,激光工作在单纵模运转状态;输出激光的3 dB线宽为3.4 kHz。     

窄线宽光纤激光器关键技术研究

文章介绍了实现窄线宽光纤激光器的线宽压缩方法，并采用掺Er^3＋光纤作为增益介质，980nmLD激光器作为泵浦源，直线腔结构，光纤环行镜和光纤光栅共同作为腔镜，实现中心频率在1550nm波段的单频激光输出，并讨论了其关键技术和影响因素，为同类激光器的研制提供了参考。     

单频单偏振窄线宽光纤激光器及其放大研究

为了获得高功率单频单偏振窄线宽激光,对一个带单级放大结构的环形腔结构掺铒光纤激光器系统进行了研究。采用作为可饱和吸收体的未抽运掺铒光纤结合作为波长选择器的高反射率光纤布喇格光栅形成超窄带滤波器,在环形腔内加入光纤偏振控制器和具有高消光比的保偏环行器获得单偏振光。环形腔输出后进行单级光放大以提高输出激光光功率。获得了206mW激光输出,输出功率长时间稳定度达到1.4%。通过光纤延迟自外差线宽测试系统得到输出激光线宽小于500Hz,光纤激光器输出光偏振度长时间稳定在99.7%。结果表明,非保偏可饱和吸收体加光纤布喇格光栅结合部分保偏结构可产生单频单偏振窄线宽激光,激光放大对线宽有明显的展宽效果。     

注入锁定掺铒光纤环形腔激光器及波长调谐技术

研究了掺铒光纤环形腔激光器(EDFRL)的注入锁定现象,提出了一种实现可调谐的单纵模EDFRL波长及功率稳定的新方法,即利用注入锁定技术向法布里-珀罗可调滤波器结合复合腔结构的EDFRL腔内注入低功率的连续光,使某一纵模在注入连续光的基础上起振.这个纵模在对增益介质的竞争中可以稳定地占据优势,从而与注入信号发生锁定,实现激光器输出光谱的稳定.实验得到激光器在1527.4～1561.9 nm范围内波长可调,输出功率＞0.6 dBm,信噪比(SNR)＞43 dB;输出光波长与功率抖动分别＜0.01 nm和≤0.02 dB,且线宽约为1.4 kHz.     

注入锁定掺铒光纤环形腔激光器及波长调谐技术

研究了掺铒光纤环形腔激光器(EDFRL)的注入锁定现象,提出了一种实现可调谐的单纵模EDFRL波长及功率稳定的新方法,即利用注入锁定技术向法布里-珀罗可调滤波器结合复合腔结构的EDFRL腔内注入低功率的连续光,使某一纵模在注入连续光的基础上起振.这个纵模在对增益介质的竞争中可以稳定地占据优势,从而与注入信号发生锁定,实现激光器输出光谱的稳定.实验得到激光器在1527.4～1561.9 nm范围内波长可调,输出功率＞0.6 dBm,信噪比(SNR)＞43 dB;输出光波长与功率抖动分别＜0.01 nm和≤0.02 dB,且线宽约为1.4 kHz.     

有源光纤环形腔的频率滤波特性

本文首先从理论上通过简单的分析得以了有源光纤环形腔的输出谱密度函数公式，该式清楚地表明光纤环形腔的频率滤波特性。从该公式出发，详细分析了环形腔输入光纤宽和环形腔参数对输出光谱谱型和线宽的影响。最后，通过设计不同的环形腔的自由谱宽和不同线宽的激光器作为输出光源，对上述理论分析做了实验验证。理论和实验表明，由于环形腔的强度传递函数是多峰的响应函数，环形腔自由谱宽和输入激光线宽的大小直接影响到环形腔输出光频谱形状，即是单峰输出还是多峰输出，对于不同形状的光谱输出，输出激光的线宽受环形腔的参数影响也各不相同。     

Diode lasers locked to noisy injection

We have analyzed the behavior of a diode laser with low-amplitude optical injection. The noisy injection field has phase fluctuations only, with a linewidth larger than both the free-running slave laser linewidth and the locking range. Simulations show that the laser output spectrum can be much narrower than the injection spectrum and may have a dip at the free-running laser frequency. A model describing these features is based on linear superposition of the stationary responses to monochromatic injection. The mechanism of line narrowing is that the response to injection outside the locking range lies mainly inside     

Single-polarization operation of fiber distributed feedback (DFB)lasers by injection locking

This paper investigated injection locking characteristics of a fiber distributed feedback (DFB) laser operating in dual polarizations, and found that it could operate in a single polarization by injection locking. The locking bandwidth was less than 10 MHz, much narrower than DFB laser diodes as a consequence of longer cavity length and resulting longer photon lifetime. As a more practical method to realize single-polarization operation of the fiber DFB laser, we proposed self-injection locking with a polarization-selective optical feedback composed of a mirror and a polarizer, and demonstrated a stable single-polarization operation     

Fabry-Perot semiconductor laser injection locking

Injection locking of a semiconductor laser is studied using a Fabry-Perot (FP) model. For low injection powers the FP model gives the same results as the rate equation model. At higher injection powers, the FP laser has an unlimited injection locking bandwidth; however, regions of the bandwidth are dynamically unstable. The influence of the linewidth enhancement factor on injection locking and its stability are also studied using the FP model. Finite values of the linewidth enhancement factor lead to increased locking bandwidth, asymmetry in the locking range and a saddle-node bifurcation in the injection locked solutions, of which only lower carrier density arm has linearly stable solutions.     

Analytical model for injection-seeded erbium-doped fiber ring lasers

We present a model for the injection seeding of a fiber ring laser. Agreement between theory and experiment is found to be excellent. An injection-seeded fiber laser is attractive for lidar applications requiring narrow linewidth and highly stable peak output wavelength.     

Propagation equation based theory of intermodal injection lockingin semiconductor lasers

Intermodal injection locking is analyzed theoretically through the use of propagation equations inside the amplifying semiconductor medium and the boundary conditions on the laser facets. In particular, the stability analysis is performed by considering the oscillation threshold of sideband waves generated inside the laser via intracavity nearly degenerate four-wave mixing processes. This study of injection locking is performed by taking into account the dispersion relationship of both the optical gain and linewidth enhancement factor. As a consequence, in intermodal injection locking, the injected-locked power is shown to be, in certain cases, lower than that of the free-running laser, and the frequency zones of stable injection locking broader than those obtained in the intramodal injection-locking case usually considered     

窄线宽光纤激光振荡器研究进展（特邀）

窄线宽光纤激光器在遥感探测、非线性频率转换和光束合成等领域具有重要的应用价值。介绍了窄线宽光纤激光振荡器的典型谐振腔结构及其工作原理,从实现更窄线宽的角度梳理了单频选模技术,从获得更高功率的角度梳理了功率提升技术,综述了窄线宽光纤激光振荡器的研究现状,并对窄线宽光纤激光技术的发展进行了展望。     

Bistability and Switching Properties of Semiconductor Ring Lasers With External Optical Injection

We investigate both analytically and numerically the switching, locking and stability properties of a bistable semiconductor ring laser subject to an external optical injection. Minimum optical power required for the injected signal at certain frequency to switch the lasing direction of a bistable semiconductor ring laser from its initially lasing direction to initially nonlasing direction is determined. Locking to the injected signal and stability of the switched laser are investigated to give an area of reliable switching operation. Correspondingly, numerical simulation has been carried out to find successful switching and stable locking region with variable injection power and frequency, and is compared with the analytical results. The region obtained from simulation coincides well with the intersection of switching, locking and stable locking regions. The relation between switching speed and parameters of injected source is also studied numerically.     

采用F-P光纤环滤波器的窄线宽环形腔光纤激光器

提出了一种采用F-P光纤环滤波器的窄线宽环形腔激光器,该激光器采用环形腔结构,两个耦合比为30:70的耦合器和一段2 m长的未泵浦掺铒光纤构成F-P光纤环滤波器,F-P光纤环滤波器产生的梳状谱,可以增大激光模式之间的自由光谱范围（FSR）,在一定程度上减小跳模现象的发生,有利于模式的稳定。研究表明,通过对掺铒光纤的优化和耦合器的选择可以提高F-P光纤环滤波器的精细度,而F-P光纤环中的未泵浦掺铒光纤起到饱和吸收体的作用,使输出激光的线宽得到有效压缩。将保偏光纤光栅和F-P光纤环滤波器共同应用于环形腔掺铒光纤激光器,在室温下得到了3 dB线宽均小于0.07 nm（实验室光谱仪最小分辨率）的窄线宽双波长输出。在2 h的观测时间内,最大峰值功率波动小于0.4 dB,具有良好的稳定性。     

Laser frequency control using an optical resonator locked to anelectronic oscillator

A new method for controlling a laser's center frequency is reported. This method extends the Pound-Drever-Hall technique, which delivers exceptional laser linewidth. The new technique, applicable over a broad range of wavelengths, produces a laser beam with both narrow linewidth and stable center frequency. A diode-pumped ring laser is locked to an ultrahigh-finesse, tunable optical resonator which, in turn, is locked to an electronic (5 MHz) oscillator using a difference frequency developed by locking a second laser to the resonator. A 1064-nm beam is reported with linewidth less than 0.004 Hz and center-frequency stability given by the electronic reference. For the case of an oven-controlled quartz crystal, the laser center-frequency stability is less than 1 part in 10¹¹ per day with root Allan variance of 10^-12 for a 1000-s time delay. The entire system is compact, and all elements are solid-state, making it useful both in the laboratory and in a number of space-based applications