A tunable waveguide CO2 laser using Fabry-Perot modulator and fox-smith type mode selector

A tunable waveguide CO₂ laser was constructed and tested. Efficient output was obtained over expanded tuning range making use of the coupling modulation through the F-P modulator. A fox-smith type mode selector was used to obtain the tuning range wider than the longitudinal mode spacing. A continuous tuning range of 2.2GHz was experimentally obtained.     

Tunable single- and double-frequency diode-pumped Nd:YAG lasers

An Nd:YAG 1-cm-long crystal has been used as the active medium for tunable single- and double-frequency lasers with a metallic absorbing thin-film selector. Cobalt and chromium thin films (210-nm thickness) were used for mode number and frequency control. The laser with a short cavity (25 mm) provided slow smooth tuning up to 6 GHz, the frequency chirp up to 4 GHz with repetition rate about 0.5 kHz and hop tuning over 150 GHz at a maximum pump power of 1.8 W. 520 mW of single-frequency output power was achieved. Double-frequency operation with a space of 1.5-2.5 GHz was realized in a laser with cavity length up to 100 mm     

On the spectral properties of widely tunable lasers usinggrating-assisted codirectional coupling

The analysis of mode-suppression-ratio (MSR) and wavelength tunability of widely tunable semiconductor lasers using grating-assisted codirectional-coupler (GACC) filters is considered. A tradeoff is found between tuning range and spectral purity when using this type of filter as an intracavity mode selector. It is shown that in order to improve the tuning range by a factor of 10 compared to a conventional tunable laser using distributed feedback reflectors (DBRs), one has to tolerate a MSR around 23 dB at 1 mW output optical power/facet for an ideal cavity design. Limitations imposed by the materials are illustrated with design curves based on a vertical-twin-guide structure in both GaAs and InP systems for lasing wavelengths at 0.98 and 1.55 μm, respectively     

L-band tunable erbium doped fiber ring laser using fiber loop mirror filters

We present a novel and efficient L-band wavelength-tunable Er^3＋ doped fiber laser of ring structure. In the cavity two segments of Er^3＋ doped fiber and a fiber Bragg grating are used to improve pump efficiency. Tunable filters based on fiber loop mirrors are also applied inside the cavity to act as both a wavelength selector and a line-width compressor. Using these techniques, a tunable laser with tuning range up to 42 nm, output power larger than 1 mW, power uniformity controlled within 1.75 dB and side mode suppression ratio about 40 dB is achieved.     

基于体布拉格光栅选模的单纵模激光器

采用体布拉格光栅(VBG)作为纵模选择元件,组合使用透射式和反射式体布拉格光栅构成窄带滤波器进行纵模的选择,在Nd:YLF激光器中得到了单纵模几率100%,单脉冲能量2 mJ,波长1053 nm的单纵模输出.实验结果表明,体布拉格光栅用作选模元件的同时,又用作输出耦合镜,简化了单纵模激光器的结构,提高了抗干扰能力,且具有大功率输出的潜力.     

DBR单纵模光纤激光器波长温度调谐

报道了采用DBR方式,利用8 mm的高浓度掺Yb3+单模光纤,实现了波长为1 064 nm的单纵模调谐激光稳定输出的实验结果。该DBR谐振腔有效腔长为16 mm,输出最大功率为7.4 mW,通过半导体制冷器温控改变谐振腔的温度,实现了0.824 nm的单纵模无跳模调谐。采用光纤外差法,并利用低损耗环形器和光纤反射镜倍增延迟线长度提升测量精度的方式,测量得到激光最大线宽为4.4 kHz。单纵模激光的弛豫震荡峰位于900 kHz处,其相对强度噪声为-110 dB/Hz,当频率大于1.5 MHz时相对强度噪声为-145 dB/Hz。     

Design of widely tunable semiconductor lasers usinggrating-assisted codirectional-coupler filters

The analysis and design of widely tunable semiconductor lasers using grating-assisted codirectional-coupler filtering in a vertical twin-guide structure are considered. An orthogonal coupled mode formalism is applied to obtain the important design parameters for the filter. It is shown that there is a tradeoff between tuning range and spectral purity when using this type of filter as an intracavity mode selector. Practical laser structures are presented, and design considerations and limitations are discussed for GaAs and InP material systems with lasing wavelengths around 0.98 and 1.55 μm, respectively     

基于半导体光放大器交叉增益调制效应的主动锁模光纤激光器

提出一种腔内损耗小的基于半导体光放大器(SOA)交叉增益调制效应(XGM)的主动锁模光纤激光器结构。使用光环行器成功减小了激光器的腔内损耗,提高了激光器的输出功率。从理论上对有理数谐波锁模过程中腔内脉冲复合的物理机制进行了详细分析。利用有理数谐波锁模技术,在调制频率为10 GHz下,得到了重复频率为30 GHz的皮秒级光脉冲序列输出,其峰值功率约0.5 mW。由于半导体光放大器的宽增益谱与滤波器的较大可调谐范围,使得激光器输出可以在较大的波长可调谐范围内保持较大功率输出。成功实现了调制频率为20 GHz的谐波锁模短光脉冲输出,可调谐范围达40 nm,峰值功率大于0.65 mW。半导体光放大器和激光器的短腔长保证了激光器的长期稳定性。     

GaN diode-pumping of red semiconductor disk laser

A red-wavelength semiconductor disk laser (SDL) optically pumped by gallium nitride laser diodes is reported. This is believed to be the first demonstration of a directly diode-pumped visible wavelength SDL. In this initial demonstration, pump-power-limited continuouswave output power up to 12.2 mW was achieved around room temperature in a single transverse mode with 2% output coupling. Insertion of an intracavity birefringent filter allowed tuning of the output over 11 nm around a centre wavelength of 672 nm.     

Tunable CO2waveguide laser with high transverse mode and line discrimination

A CO2waveguide laser with a special resonator configuration is described. The resonator mirrors with curvature radiiRare located at a distanceR/2from the ends of the waveguide tube. The properties of this resonator, such as transverse mode control and line discrimination, are discussed and measurements concerning the tuning characteristics and the laser output power are presented.     

1.35 GHz线性调频Nd:YVO4激光器

报道了808 nm连续半导体泵浦全固态Nd:YVO4线性调频激光器实验研究。利用优化谐振腔长度、腔内插入倾斜标准具，采用温度控制、机械减震和隔绝外部环境等稳频操作，实现了稳定的1 064 nm单频激光输出，最大输出功率140 mW。利用法柏干涉仪观察单频输出，并利用刀口法测量得到的基模高斯光束质量M2为1.05。在谐振腔内插入RTP电光晶体并连接外部高压电源，通过线性电光效应改变谐振腔长度以及改变标准具倾斜角度避免腔长调节过程中的模式跳频，实现了1.35 GHz的稳定线性调频激光输出。编程控制高压电源给RTP晶体施加幅值为2 200 V的锯齿波形电压，实现了频率20 Hz，平均输出功率为85 mW周期性的调频信号输出。     

用于遥感探测大气水气分布的电光快速调谐红宝石激光器

研制了一种电光快速调谐红宝石激光器。方解石-KDP晶体组成快速调谐部件,F-P共振选频元件用于进一步精确控制波长,并形成阶跃式的调谐曲线,在一次点火中即能输出波长不同的两个脉冲。文中对激光器工作原理和调谐特性作了详细分析。     

基于全介质薄膜法布里珀罗滤光片的1550 nm可调谐外腔半导体激光器

提出并实现了一台基于单腔全介质薄膜法布里珀罗滤光片的1550 nm可调谐外腔半导体激光器。介绍了其内部的光学元件及其工作原理,随后对该半导体激光器的纵模输出特性进行了理论分析,搭建了该可调谐外腔半导体激光器。在不同的实验条件下,对该可调谐外腔半导体激光器在调谐过程中的输出波长、线宽及功率进行了实时同步测量。由所测数据总结出最佳实验条件,并得到了此条件下可调谐外腔半导体激光器的各相关参数。该可调谐外腔半导体激光器有一个线性的无跳模波长调谐区域(1547.203~1552.426)nm,一个稳定的输出光功率范围(40~50)μW,以及一个稳定的输出单纵模分布、线宽范围(100~150)MHz。该可调谐外腔半导体激光器可用于环境监测、原子与分子激光频谱研究、精确测量等领域。     

可调谐单频掺镱光纤DBR激光器

对分布布拉格反射(DBR)的透射特性进行了分析,制作了一个单频窄线宽掺镱光纤DBR激光器.在977 nm半导体激光器泵浦下,在1052.5 nm波长处输出功率可达4 mW,线宽小于8 MHz(受测量仪器分辨率限制).采用弧形梁调谐光纤光栅,实现了DBR光纤激光器在单纵模工作状态下的连续调谐,调谐范围可达20.4 nm(1036.1～1056.5 nm),并研究了调谐对激光器的泵浦阈值和斜率效率的影响.     

The side-mode-suppression ratio of a tunable DBR laser

The authors investigate, both experimentally and theoretically, how the side-mode-suppression ratio (SMSR) of a multisection multiple-quantum-well distributed-Bragg-reflector (MQW-DBR) laser varies with tuning current. It is found that as the tuning current is adjusted the wavelength and the SMSR vary, with the peak SMSR=43 dB. The output power also varies with tuning current, and one can find when the laser is near a mode hop by examination of the light versus tuning current curve. This implies that the tuning current can be adjusted so that the laser frequency is near the center of the Bragg band without measuring the SMSR. The measurement are in good agreement with theory     

Barium borate optical parametric oscillator

Experimental results of the first BaB₂O₄ optical parametric oscillator (OPO) are presented. The pump source was the second harmonic output of a Q-switched TEM₀₀ mode Nd:YAG laser. The OPO had 1 mJ output energy with a peak power of 80 kW in a tuning range from 0.94 to 1.22 μm     

Mode stabilization method for superstructure-grating DBR lasers

A wavelength stabilization method for widely tunable superstructure-grating (SSG) distributed Bragg reflector (DBR) laser is described. The output characteristics under tuning are studied theoretically and experimentally. It is found that peak reflectivity states, in which the lasing mode is just aligned with the reflection peaks of both DBR's, are obtained at saddle points in the output characteristics while changing the two SSG-DBR currents. Based on these results, a method for the Bragg frequency control of the two SSG-DBRs is proposed. The feedback control circuit keeps the lasing mode at a peak reflectivity state, and it suppresses mode hopping. Additionally, the oscillation mode is locked to arbitrary reference wavelengths of an optical filter. Stabilization at 200 GHz (1.6 nm)-spaced 16 wavelengths was achieved within the wide tuning range of the SSG-DBR laser. Control was maintained under a laser temperature variation of ±5°C as a result of the Bragg frequency control of the two DBR's     

低阈值光纤激光器稳频特性研究

为了实现低阈值光纤激光器的频率稳定输出,设计了环形腔光纤激光器,以光纤光栅作为波长选择元件,在未泵浦光纤饱和吸收体和其锥形化结构的协同作用下实现激光纵模选择,获得了短光纤饱和吸收体长度下的单纵模激光稳定输出。介绍了未泵浦光纤饱和吸收体选频原理和锥形结构滤波原理,实验研究了不同光纤饱和吸收体长度下激光纵模特性和波长稳定性,以及锥形化光纤饱和吸收体的激光输出特性。实验表明,引入锥形化结构的饱和吸收体后,激光器能够稳定输出1545 nm波长的单纵模激光,并有效降低光纤激光器阈值至7.58 mW,采用延迟自外差方法测得该光纤激光器的线宽小于8 kHz。     

平坦功率输出的宽带波长可调光纤环型激光器

为了获得一种平坦功率输出的宽带波长可调的掺铒光纤环型激光器,提出采用一高双折射光纤环镜获得其平坦功率输出,在高双折射光纤环镜中,采用了大量的高双折射光纤段和偏振控制器,它们的反射光谱可补偿掺铒光纤环型激光器输出功率光谱的不平坦,通过压缩或者延伸激光腔里的分布式光纤布喇格光栅即可实现波长调谐。实验验证可以获得一种宽达38nm的宽带波长调谐(1527nm～1565nm),输出功率的不平坦被控制在±0．8dB范围之内,总输出功率大约4dBm、3dB线宽为0．01nm、旁瓣抑制比为48dB的光纤环型激光器。