外腔半导体激光器单频输出的长期稳定

一、引言 由于光纤通讯、光纤传感、检测二光谱分析、频标、光陀螺等领域的需要；单频半导体激光器的研究近年来受到广泛重视并得到迅速发展，由于采用了长外腔选模技术，已实现了线宽小于100 kHz的单频输出~[1-3]。而频率长期稳定工作则刚刚开始~[4]。通常认为，造成半导体激光器输出频率漂移及跳模的原因是管芯温度和注入电流的波动，因此稳频工作     

Tuning characteristics of a tunable-single-frequencyexternal-cavity laser

The lasing characteristics of a tunable-single-frequency laser operated in conjunction with a tunable external cavity are investigated. The effect of phase error in the external cavity on the lasing frequency, linewidth, and output power is calculated by deriving the characteristic equation for the FP cavity as a traveling amplifier with an effective mirror concept. The analysis suggests that the diode laser and the external cavity may be successfully tuned open-loop if the feedback strength is appropriate and the tuning nonlinearities in the active and passive cavities are not too severe. This is demonstrated by maintaining a linewidth of 4 MHz while tuning continuously over 34 GHz     

24 h frequency stabilisation of an SLM external-cavity semiconductor laser

Long-term single-frequency stabilisation of an external-cavity semiconductor laser has been demonstrated using a multisegment composite-cavity configuration and an automatic frequency control loop with feedback to the external cavity. Mode-hopping free single-longitudinal-mode oscillation with a linewidth of about 200 kHz and a frequency shift within 28 MHz has been observed over 24 h.     

Littrow型光栅外腔半导体激光器的输出特性分析

在讨论光栅外腔半导体激光器理论的基础上.对影响Littrow型光栅外腔半导体激光器输出功率和线宽压窄的各种因素进行了数值模拟分析.研制了单纵模高质量激光输出的Littrow型光栅外腔半导体激光器,在工作电流为400 mA时,连续输出功率达到180 mW,线宽优于1 MHz.     

1.52μm,60kHz线宽光纤布拉格反射镜外腔半导体激光器

本文报道1.52μm光纤布拉格反射镜外腔窄线宽半导体激光器的制作和实验结果,已实现光谱线宽60kHz,边模抑制比优于30dB,输出功率>-5dBm,频率稳定度为50MHz。     

Optical feedback phase stabilization of a semiconductor laser

The phase of optical feedback into a semiconductor laser was stabilized to maintain a minimum linewidth of 2 MHz. The scheme makes use of the linewidth information provided by a 1-MHz width external resonator. A further reduction in the laser linewidth to 300 kHz can be achieved and stabilized by using an external resonator with a narrower width.     

Characteristics of linewidth-narrowed distributed Bragg reflectorlasers with a fiber external cavity formed with the vertical gratingemission

Linewidth reduction has been observed in a distributed Bragg reflector (DBR) laser with a second-order grating when an external cavity is formed with the vertical emission. The external cavity consists of a length of optical fiber which is brought close to the top of the laser. Displayed linewidths as low as 26 kHz have been measured. To the authors' knowledge, this is the first report of linewidth reduction via vertical emission from a laser diode     

光纤光栅外腔反馈的高功率半导体激光器光谱特性的研究

对光纤光栅外腔反馈的高功率半导体激光器的光谱线宽特性进行了理论与实验研究。理论分析表明，根据不同的外腔参数，激光器的线宽能被压缩或展宽。外腔反射率对光谱线宽的影响要比外腔腔长灵敏得多。实验实现了激光器的线宽由６ｎｍ到０．８ｎｍ的压缩。光纤光栅外腔反馈不仅能改善高功率半导体激光器的光谱特性，而且可提高激光器主模对次模的抑制比。     

Spectral linewidth rebroadening with short wavelength detuning in external cavity lasers

The first experimental observation of spectral linewidth rebroadening when an external cavity semiconductor laser is detuned well away from the laser gain peak on the shorter wavelength side has been made. This confirms a recent theoretical prediction of the variation of the effective linewidth enhancement factor with shortwave detuning and has significant implications for the design of narrow linewidth optical sources.<>     

Spectral linewidth of AlGaAs/GaAs surface-emitting laser

The spectral linewidth Delta nu of a vertical cavity surface-emitting (SE) laser was measured for the first time. The linewidth measured by a delayed self-homodyne method was 50 MHz at an output power of 1.4 mW under room-temperature CW operation. The linewidth obtained was guite narrow in spite of the short cavity configuration of the SE laser. This narrow linewidth is attributed to the high-reflectivity mirrors. The measured linewidth is in good agreement with theoretical values.<>     

高稳定度窄线宽激光器的研究

介绍了3种不同类型的高稳定度窄线宽激光器的研究进展.基于Littman结构和饱和吸收光谱稳频技术,研制了稳频外腔半导体激光器系统,输出波长为780.2 nm,频率稳定度1 MHz,不失锁时间大于12 h.利用边带稳频技术将分布反馈(DFB)激光器的输出波长稳定在Cs原子的吸收谱线的边带处,引入数字信号处理器(DSP)全数字稳频控制技术,实现了自动找频和稳频,获得波长为852.3 nm的稳频激光输出,24 h内频率漂移为±2 MHz.利用国产磷酸盐玻璃光纤作为增益介质,实现了一台高功率单纵模光纤激光器,制作的厘米级激光器实现了最大输出功率100 mW,利用外部光反馈实现单偏振运转,测得输出线宽为2 kHz,偏振消光比优于35 dB.     

Theory of spectral linewidth of external cavity semiconductor lasers

A new formula of the spectral linewidth of external cavity semiconductor lasers is proposed, with which linewidth narrowing with the optical feedback is discussed. It is shown that in the limit of large external cavity length, the linewidth caused by the phase diffusion due to spontaneously emitted photons becomes dominant and the linewidth decreases proportionally to the inverse of the external cavity length.     

Self modulation at gigahertz frequencies of a diode laser coupled to an external cavity

An external cavity coupled to a continuously operating GaAs diode laser has been found to cause modulation of the light output at a frequency within the range of 0.6?2.2GHz. The modulation depth is close to 100% and the linewidth is 200kHz.     

Narrow spectral linewidth 150 mW semiconductor laser with fundamental transverse mode for SHG light source

A highly reliable, narrow spectral linewidth, 150 mW high-power semiconductor laser that oscillates at a wavelength of 860 nm has been developed, by optimising the structure with a 0.7 mu m thick p-cladding layer, a 900 mu m long cavity length, and current-blocking regions near the facets. Stable, fundamental transverse mode operation was obtained up to 230 mW. The spectral linewidth was 5 MHz at 150 mW. stable operation under 150 mW at 50 degrees C was confirmed for more than 2000 h.<>     

A compact external cavity wavelength tunable laser without an intracavity etalon

We propose a novel external cavity wavelength tunable laser (ECTL) configuration without an etalon inside the cavity. ECTL consists only of a semiconductor optical amplifier with an integrated phase section, and a liquid crystal tunable mirror. We successfully demonstrated excellent performances of the ECTL with fiber coupled output power of more than 50 mW over a 40-nm tuning range, sidemode suppression ratio of better than 45 dB, relative intensity noise of better than -148 dB/Hz, and linewidth of narrower than 2.3 MHz.     

基于Littrow结构的可调谐半导体激光器

市售的商用半导体激光器由于其线宽宽、抖动和漂移大等缺点,不能满足离子阱中单个钙离子的激光冷却和精细测量实验的要求。因此,制作了一台可调谐的Littrow结构的半导体激光器(ECDL).该激光器的自由光谱程为1.5GHz,通过精细调节光栅的角度,激光的波长可以覆盖775~785nm.该激光器的线宽约为2.5MHz,抖动为3~4MHz,30min内的漂移约为50MHz,这些指标优于商用的DL100半导体激光器,为下一步用于单个钙离子的激光冷却和精细测量所需要的397nm和866nm激光器的制作提供了条件。     

Intensity noise suppression and modulation characteristics of a laser diode coupled to an external cavity

Static and dynamic properties of a GaAlAs laser diode with an external cavity (1.5-50 cm) have been studied experimentally, it is found that the optical feedback induced intensity noise is strikingly suppressed by 30 dB when a single frequency oscillation is realized with good phase matching. The threshold of modulation depth, over which intensity noise increases abruptly, has been measured as a function of the modulation frequency in a range of 10-400 MHz. It has the maximum at about 40-70 MHz and increases with the decrease of the external cavity length. On the basis of the compound cavity model the phase and gain conditions for the single frequency oscillation are discussed and the threshold modulation depth is calculated, which is shown to be in good agreement with the experimental results.     

Tunable operation of a gain-switched diode laser by nonresonantself-injection seeding

We report tunable operation of a gain-switched diode laser by nonresonant self-injection seeding from an uncoated glass slide used as an external cavity reflector. A spectral linewidth reduction from 11 to 0.05 nm has been achieved for picosecond pulses with little effect on other laser characteristics. Good agreement with numerical simulations based on a compound-cavity laser model is also reported     

Narrow spectral linewidth 1.5 μm GaInAsP/InP distributed Braggreflector (DBR) lasers

The spectral linewidth of distributed Bragg reflector (DBR) lasers is discussed. The narrowest linewidth of 3.2 MHz was obtained at P =1.5 mW. It was found that narrow spectral linewidths can be obtained constantly for the DBR lasers with long and low optical loss corrugation regions, and with a small coupling coefficient. These results are explained by the external cavity model, which is used in the theoretical analysis. To increase the output power of the narrow-linewidth DBR lasers, AR (antireflection) coating was applied to the output facet. Improved quantum efficiency and submode suppression were achieved. Degradation of the linewidths by the AR coating was insignificant     

准直透镜失调对Littman-Metcalf光栅外腔激光器线宽的影响

以光栅外腔半导体激光器的理论知识为基础,对Littman-Metcalf型外腔半导体激光器的工作原理进行了说明,并详细地讨论了外腔半导体激光器的线宽压窄以及模式选择机制,采用严格的耦合理论和光线变换矩阵推导了系统结构参数对光场耦合效率影响的计算公式。同时,对影响Littman-Metcalf外腔激光器输出激光线宽的几个重要因素进行了分析,重点讨论了系统中准直透镜位置失调导致的线宽变化规律。计算结果表明:合理地控制Littman-Metcalf光栅外腔半导体激光器的外腔参数可以将中心波长为785 nm半导体激光器的本征线宽压窄四个数量级,该外腔系统中准直透镜位置失调会影响系统出射光场与经外腔反馈光场之间的耦合效率,进而影响光栅外腔半导体激光器的输出线宽。