单频光纤激光器相位噪声的影响因素

单频光纤激光器是光纤通信中最具前途的一种光源,在光纤传感、激光雷达和激光测距等方面具有重要的应用,而相位噪声是衡量其性能的关键指标之一。采用示波器和动态信号分析仪方法对单频光纤激光器的相位噪声进行测量。利用功率谱、积分谱对不同泵浦源功率、种子源功率和波长的光纤激光器的相位噪声进行定性分析,结果表明:泵浦功率越大,低频相位噪声所占比重越大;而对于不同种子源功率,相位噪声在测试频段的比例基本处于同一水平;对于测试的不同种子的波长,相位噪声高频段所占比例不同,其中种子波长为1 560.48 nm比例最大。     

偏置信号和噪声对单模激光随机共振的影响

为了研究激光系统的性质,采用色抽运噪声和实虚部关联的量子噪声驱动的单模激光损失模型,用线性化近似方法,对单模激光系统的输出光强信噪比进行了理论分析;并具体分析了调制信号振幅、低频调制信号频率、高频载波信号频率、量子噪声强度、抽运噪声强度以及量子噪声实部、虚部间的关联系数对系统随机共振的影响。结果表明,信噪比随激光系统净增益系数存在随机共振现象。此结果对优化激光动力学提供了理论依据。     

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。     

窄线宽低噪声可调谐非平面环形激光器

针对空间相干光通信和探测等应用,对非平面环形激光器的线宽、噪声和调谐特性进行了系统的实验研究。单频输出功率达到752mW,光光效率42%,斜率效率54%。采用延时自外差拍频法测试了激光线宽,其随泵浦功率的增加而增大,输出功率小于200 mW 时,线宽小于1 kHz,在最高输出功率下线宽为2.3 kHz。激光强度噪声主要由弛豫振荡引起,相对强度噪声（RIN）随着泵浦功率的提高而降低。在1.78W 泵浦功率下,RIN 达到-93 dB/Hz。采用温度和压电两种方式进行了激光调谐。温度调谐范围达到62 GHz。压电调谐范围达到130MHz,响应带宽100 kHz。     

Submillimeter wave generation through optical four-wave mixingusing injection-locked semiconductor lasers

This paper presents a comprehensive analysis of submillimeter wave generation through optical four-wave mixing (FWM) in an injection-locked semiconductor laser. The probe wave introduces pump-probe difference frequency amplitude modulation (AM) and phase modulation (PM) of the slave laser injection locked to the pump wave. The AM and PM indexes of the locked laser output lightwave modulated at the submillimeter wave frequency have been calculated. The submillimeter wave power generated through this technique has also been calculated theoretically. The analysis predicts a submillimeter wave power of -3.7 dBm at 300-GHz frequency for a free-running slave laser output power of 30 mW. In the presence of amplitude modulation of the probe wave, the same modulation is transferred to the submillimeter wave. The suppression of output lightwave amplitude noise relative to the pump, probe, or free-running slave laser amplitude noise has also been estimated in this analysis. At a submillimeter wave frequency of 300 GHz and a probe power equal to the pump power, typical amplitude noise reduction occurs by 7 dB     

Optimum Er3+-doped fiber amplifier design for optical AMvideo signal distribution systems

An investigation into the transmission characteristics of erbium-doped fiber amplifiers for use in optical AM frequency division multiplexing (FDM) video distribution systems is reported. The output signal power and noise characteristics of erbium-doped fibers were measured for different fiber lengths and different pump powers. The experimental results confirm that there exists an optimum amplifier design which gives the maximum distribution number when the pump power and the required video quality are given     

半非平面单块激光器强度噪声及其抑制的研究

实验研究了半非平面单块固体环形Nd∶YAG激光器的强度噪声特性和抑制技术。结果表明,弛豫振荡仍是该种激光器强度噪声最主要的来源。噪声峰值频率随抽运和输出功率的增加向高频方向移动,同时噪声峰宽度增加幅度降低,且在峰值频率附近发生180°相位跃变。采用光电反馈方法设计和制作了包含低噪声宽带接收、比例积分微分(PID)调整等单元组成的噪声抑制电路,测量了整个系统及各部分的传递函数,实现了强度噪声的抑制。当弛豫振荡峰值频率为600kHz时,噪声峰值处和低频区域幅度降低分别接近40dB和15dB。     

输入信号后单模激光系统线性化近似适用范围分析

运用线性化近似方法计算泵噪声和实虚部间关联的量子噪声驱动的单模激光系统输入信号后的稳态平均光强关联函数和稳态平均光强相对涨落，对所用线性化近似方法的适用范围进行了详细分析，具体讨论了量子噪声实虚部间关联系数、量子噪声强度、泵噪声强度、输入信号振幅和频率、净增益等对稳态平均光强相对涨落的影响，发现在量子噪声实虚部间弱关联、小噪声、远离阈值、信号强度不大和频率较高的条件下，线性化近似有较高精度。     

高次谐波锁模飞秒掺镱光纤激光器的噪声情况

高重复频率的飞秒激光在高速激光测距和三维成像等领域有着非常重要的作用。其中基于飞秒光纤激光器的高次谐波锁模是获得GHz量级以上高重复频率脉冲的重要手段之一。基于含腔内光栅对色散补偿的非线性偏振旋转（NPR）锁模的掺镱（Yb）光纤激光器,在180 mW泵浦光时获得了稳定的143 MHz基频锁模脉冲序列,当泵浦光功率升至1 W时获得了最高20次谐波（2.86 GHz）锁模脉冲序列输出。系统地对比研究了基频锁模与高次谐锁模状态下,脉冲重复频率精密锁定后的艾伦偏差和相位噪声,7次谐波锁模状态下重复频率锁定精度能够保持在10?13 Hz@1 s的稳定度,为高次谐波锁模飞秒激光脉冲序列用于精密测量提供了实验依据。     

氦镉激光器的噪音研究

本文在实验上研究了氮镉激光噪音的起因和特性，得到氦镉激光噪音的起因是多重的。行走辉纹、气压差及镉浓度波都是产生噪音的重要原因。气压差及镉浓度波可使噪音增大很多倍，浓度波主要增强了低频噪音。适当增大激光管内平均镉浓度和采用扩散迴路后，可显著降低激光噪音，获得大功率低噪音的氦镉激光器。     

Effect of pump laser noise on an erbium-doped fiber-amplified signal

The effect of pump laser noise on erbium-doped fiber-amplifier (EDFA) output was investigated using an optically pumped semiconductor laser (OPSL) as a high-power pump. Measurements included pump and amplified signal relative intensity noise (RIN) in frequency and time domains as well as gain spectral measurements and 10-Gb/s Q-factor tests, all under several levels of backreflection to the pump laser. Time-domain low-frequency noise (<50 kHz) was observed to increase with increasing backreflection. With 150-mW OPSL output power and -28 dB backreflection, temporal RIN was /spl sim/3.4% for the pump and /spl sim/2.2% for the amplified signal. At a maximum pump power of 450 mW, RIN was 1.4% and 1.1%, respectively. The measured Q-factor of 12.5 dB at 10 Gb/s showed less than 0.5-dB penalty compared to a back-to-back system measurement of 13 dB. Power budget and operating specifications of an OPSL-pumped multicoil EDFA were also evaluated.     

单频激光宽频段频率和强度噪声测量技术

报道了一种mHz至MHz宽频段激光噪声的规范测量技术。通过研制基于迈克耳孙光纤干涉仪的相关延时自外差频率噪声测量装置和具有定标功能的光外差拍频测量装置,结合频谱分析仪和快速傅里叶变换分析仪等标准仪器,规范地测量出了单频激光在mHz至MHz宽频段内的频率和强度噪声特性,并验证了测量结果的准确性。该测量技术有望应用于引力波探测和精密测量等应用中的激光噪声评估。     

In situ characterization of laser diodes from wide-band electrical noise measurements

The wide-band electrical noise characteristics of 0.8-, 1.3-, and 1.5-μm laser diodes have been studied theoretically and for the first time also experimentally. The electrical noise is related to the optical intensity noise behavior, and can therefore be used for in situ measurements and characterization of laser diodes. Since the measurements are performed without any optical components, undesired optical feedback is eliminated. The results show that several important laser parameters and characteristics can be extracted from purely electrical noise measurements. Among these are the relaxation frequency, the threshold current, the emission linewidth, optical feedback properties, and longitudinal mode hopping behavior. Good agreement between the noise theory and the electrical noise measurements has been obtained. An expression for obtaining both the spectral linewidth and lineshape from electrical noise measurements is also derived.     

分布反馈光纤激光器自放大特性实验研究

通过相位掩膜板移动法,制作了非对称相移结构分 布反馈光纤激光器(DFB-FL)。为了获得更高的激光功率,利 用同样长度的掺铒光纤(EDF),分别采用同向泵浦和反向泵浦结构方式进行了窄线宽激光信 号的自放大实验,结 果表明,两种自放大结构的DFB-FL均可充分利用泵浦光功率,在保证激 光线宽展宽有限的前 提下,实现了激光信号至少23dB的功率放大。同时,实验结果对比 说明,同向泵浦放大结构更有利于保 持原激光信号的噪声特性。这为较大输出功率的DFB-FL提供了一种简单 可行的方案。     

RbCl:Li color center laser with laser diode pumping

CW operation of a RbCl:Li-F_A(II) laser has been obtained under pumping by a red laser diode. Pump power at threshold is 90 mW. Single frequency operation of the color center laser has been achieved. The intensity noise generated by two pump sources (laser diode and Kr-ion laser) is compared     

单频光纤放大器中泵浦作用的相位噪声

研究了铒镱共掺单频光纤放大器中100 Hz～1 kHz频段内的相位噪声,并通过实验证明该尖峰噪声为泵浦电源产生的相位噪声。从铒镱共掺光纤放大器的功率传输方程出发、结合泵浦激光的热传递函数,数值分析了泵浦功率、泵浦波长、增益光纤长度对100 Hz～1 kHz频段内相位噪声的影响。通过二级光放大结构对输出激光的相位噪声进行测量,并将实验结果与数值仿真结果进行对比,证明了理论模型的可靠性。该研究优化了主谐振功率放大结构铒镱共掺单频光纤放大器的相位噪声特性、并为提高相干合成时的合束效率提供指导。以上所得结果普遍适用于主谐振功率放大结构的光纤放大器。     

高稳定性单纵模布里渊光纤激光器的实验研究

本文提出了一种用可调谐半导体激光器（TLS）泵浦的高稳定性单纵模布里渊光纤激光器（SLMBFL）。该激光器利用Brillouin泵浦光（TLS激光）只在环形器内运行一次,这样Brillouin泵浦光就不会在谐振腔内共振,确保了激光器谐振腔的高稳定性从而使Brillouin激光在该谐振腔内形成共振而输出。实验发现当Brillouin增益介质光纤的长度缩短到13．4m时谐振腔的自由光谱范围变为15．2MHz,正好与光纤的Bfillouin增益带宽接近,此时SLMBFL开始表现为单纵模振荡。实验结果表明,该光纤激光器的功率转化效率为42．5％,最大输出功率为267．6roW。单纵模激光输出的信噪比与其泵浦激光的信噪比提高近10dB。SLMBFL对TLS的高频噪声有很好的抑制作用,其输出线宽小于5KHz。     

Single-frequency operation of an optically pumped monolithic Nd:YAG laser at 1.3 ?m

The design and of a monolithic Nd:YAG laser operating at 1.3 ?m is reported. The laser is pumped by a dye laser operating at 590 nm and exhibits a threshold pump power of 2.6 mW with a slope efficiency of 32%. The frequency stability is about 2 MHz and is limited by amplitude noise from the pumped laser.     

光泵THz激光器输出特性的影响因素分析

设计稳定可靠的THz激光器, 缩小THz激光器的体积一直是THz领域的研究热点。基于速率方程组, 建立了光泵THz激光器的理论模型。数值模拟和分析了不同工作温度、腔内压强、腔尺寸、泵浦光波动等因素对THz激光输出产生的影响。研究结果表明: 泵浦光功率越高, THz激光输出对工作温度的变化越敏感, 则越有必要建立稳定可靠的温度控制系统;在保持功率输出一定的前提下, 通过适当提高THz激光腔内工作气体压强, 可以缩小THz激光器的体积;泵浦光功率越低, THz激光的输出性能对泵浦光功率波动及频率漂移越敏感, 此时, 需要对泵浦光稳定性进行控制, 更为关键的在于控制泵浦光的频率稳定性。     

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。