可调谐半导体激光器研究及进展

可调谐半导体激光器是新一代密集波分复用系统以及全光网络中光子交换的关键光电子器件 ,它的运用使得光纤传输系统容量大大增加 ,灵活性和可扩展性大大增强 ,目前已经实现了宽波长范围的连续或准连续调谐 ,并有相应的产品投放市场 .文章介绍了各种基于不同谐振腔结构的可调谐激光器以及各自的调谐机理 ,对不同类型器件在制作以及实际应用中的优缺点进行了比较 .同时总结了国外可调谐半导体激光器的最新进展 ,并对我国可调谐半导体激光器的研制提出了相应的要求     

可调波长半导体激光法布里-珀罗干涉仪

为了对激光十涉仪、高精度位移传感器等测量系统进行纳米级精度的非线性误差校准,需进一步提高中国计量科学研究院与清华大学合作研制的差拍F-P 干涉仪的线性度、稳定性及测量范围.在合理分析空气折射率变化及He-Ne激光器纵模调谐范围等因素对测量的影响基础上,设计并制作了密封干涉光路的真宅系统,并用调谐范围较大的半导体激光器作为工作激光器.实验结果表明,系统在大于1/4波长的行程范围内的线性度有明显的提高,最大非线性误差由8.93 nm减小至1.19 nm.     

微热通道电极结构宽条形半导体激光器输出特性

为了抑制宽条形半导体激光器的热透镜效应,提高慢轴光束质量,本文提出并制作了一种微热通道电极结构激光器。该芯片p面注入区电极处被设计为较厚的高热导率的电极结构,封装后激光器两侧与热沉之间形成空气间隙,抑制激光器有源区横向热流,使激光器内温度分布均匀,有效地降低慢轴发散角。对该激光器的封装模型进行了稳态热分析,优化了微热通道电极结构的厚度和宽度,并制作了波长为940 nm的微热通道电极结构激光器。测试结果表明,在注入电流为2 A时,微热通道电极结构激光器的发散角相对于普通电极结构激光器降低了24%,有效地降低了激光器慢轴光束发散角。     

基于电流内调制DFB激光器的高空间分辨率OFDR

针对光频域反射（OFDR）系统中光源调频非线性导致的传感单元定位误差、传感精度低、传感范围窄、系统适应性差等问题，提出了开环校正结合光电锁相环闭环校正电流内调制分布反馈式半导体（DFB）激光器的方法。该方法用于控制DFB激光器连续、快速、大范围频率扫描线性化，使其成为OFDR系统的优质光源，提高OFDR的分辨率。实验结果表明DFB激光器的扫频非线性度由16.55%下降至0.078%，拍频信号中心频率的功率提升了21.1 dB，探测范围由15 m提升至50 m，测量值与实际值的最大误差为3.79 mm，重复性测量的最大标准偏差为112.2μm。     

侧面泵浦高功率双包层光纤激光器的表面弧形金属槽结构的制作和分析

侧面耦合高功率泵浦光技术是获得高功率稀土光纤激光器的关键技术之一。介绍了一种用于侧面泵浦高功率双包层光纤激光器的表面弧形金属槽结构的制作工艺,并且针对已经实验制作出来的表面连续弧形金属凹槽的侧面耦合结构进行了严格的矢量电磁场理论计算,将120°弧形凹槽等效近似为多层等高不等宽的矩形槽并运用透射矩阵算法对这种近似后的多层矩形结构进行优化设计。这种结构可以用于大功率激光二极管阵列的侧面泵浦中,尤其可用于条形半导体激光器侧面泵浦双包层掺杂光纤,以制作各种大功率稀土光纤激光器。     

用于ICF驱动器的分频光栅两种工艺误差分析

 对用于ICF驱动器分频光栅的刻槽深度进行了优化，使其具有更优的分频效果。在此基础上，对制作工艺带来的占空比误差和塌边结构进行了分析，给出了分频光栅具有良好分频效果时工艺上所能允许的误差范围。     

980nm高功率列阵半导体激光器

本文分析了影响列阵半导体激光器输出功率的因素。利用分子束外延生长方法生长出InGaAs/GaAs应变量子阱激光器材料。利用该材料制作的应变量子阱列阵半导体激光器准连续（100Hz,100μs）输出功率达到80W（室温）,峰值波长为978－981nm。     

非对称结构大功率940nm量子阱激光器

为改善940 nm大功率InGaAs/GaAs半导体激光器输出特性,通过模拟计算了非对称波导层及限制层结构的光场分布,并参照模拟制作了非对称结构半导体激光器器件。采用低压金属有机物气相沉积(LP-MOCVD)生长技术,获得了低内吸收系数的高质量外延材料,通过实验数据计算得到激光器材料内吸收系数仅为0.44mm~(-1)。进而通过管芯工艺制作了条宽100μm、腔长2000μm的940 nm半导体激光器器件。25℃室温10 A直流连续(CW)测试镀膜后器件阈值电流251 mA,斜率效率1.22 W/A,最大输出功率达到9.6 W,最大光电转化效率超过70%。     

宽波长范围窄线宽波长连续可调的光纤激光器

研制了一种宽波长范围窄线宽波长连续可调的光纤激光器,激光器基于环形腔结构,采用980nm的半导体激光器作为泵浦源,掺铒光纤作为增益介质,使用一段未泵浦的保偏掺铒光纤作为饱和吸收体压窄线宽。使用光纤法布里-珀罗滤波器作为选频器件,通过调节光纤其驱动电压实现光纤激光器的波长扫描。利用激光器的相干长度与干涉仪干涉条纹的关系动态测量激光器的光谱线宽,最终得到了扫描范围为1515.1～1588.6nm,线宽小于0.025nm的波长连续可调的光谱输出。     

减反膜外腔半导体激光器特性的研究

研究了镀减反膜GaAs半导体激光器在Littrow 式外腔结构中的输出特性.采用电流补偿技术,得到了约30 GHz的连续无跳模调谐范围.利用外差拍探测技术获得激光器输出线宽约为120 kHz.还研究了激光器的强度噪声分别随着电流与波长变化的特点并对此进行了分析.该类激光器可以广泛应用在冷原子物理、激光光谱以及量子光学等许多领域. 关键词： 减反膜 半导体激光器 线宽 强度噪声     

Widely tunable mode-hop free external cavity quantum cascade laser for high resolution spectroscopic applications

An external cavity (EC) quantum cascade laser (QCL) configuration with the thermoelectrically cooled gain medium fabricated using a bound-to-continuum design and operating in continuous wave at ∼5.2 μm is reported. The EC architecture employs a piezo-activated cavity mode tracking system for mode-hop free operation suitable for high resolution spectroscopic applications and multiple species trace-gas detection. The performance of the EC-QCL exhibits coarse single mode tuning over 35 cm^-1 and a continuous mode-hop free fine tuning range of ∼1.2 cm^-1. PACS 07.07.Df; 42.55.Px; 42.62.Fi; 42.60.Fc     

Extension of the mode-hop-free tuning range of an external cavity diode laser based on a model of the mode-hop dynamics

We report on a universal method to achieve and sustain a large mode-hop-free tuning range of an external cavity diode laser based on a model of its mode-structure dynamics. Using this method, we were able to scan 73 GHz mode-hop free by using an uncoated off-the-shelf laser diode with a central wavelength of 785 nm. Our model applies to any laser system requiring synchronization of more than one optical element.     

宽带可调谐掺Yb3+双包层光纤激光器的研究

利用闪耀光栅构成可调谐Littrow外腔,对掺Yb³⁺双包层光纤激光器的波长调谐输出进行了实验研究.激光调谐输出波长范围70nm.针对光纤内的双折射效应对激光的输出功率的影响,实验中使用了在线光纤偏振控制器,从而有效地减小了调谐曲线的起伏及其与荧光谱的差别,并得到了窄线宽、线偏振、宽带调谐的激光输出.     

Widely tunable diffraction limited 1000 mW external cavity diode laser in Littman/Metcalf configuration for cavity ring-down spectroscopy

We report on recent progress on external cavity diode lasers (ECDL) using a new concept of a Littman/Metcalf configuration. Within this concept one facet of the diode laser chip is used for coupling to a high quality Littman/Metcalf resonator whereas the other side of the diode laser chip emits the output beam. The alignment of the external resonator is independent from the alignment of the output beam and there is no need for any compromise in the alignment. This results in an improved behavior of the external resonator with the benefit of a drastic increase in power and single mode tuning.We investigated this light source for high resolution spectroscopy in the field of cw-cavity ring-down spectroscopy (CRDS). The monitoring of environmental and medical gases from vehicles or human breath requires a suitable radiation source in the mid-infrared (MIR) between 3 and 5 μm that is frequency stable and can be widely tuned. Since this wavelength cannot be reached via direct emitting room temperature semiconductor lasers, additional techniques like difference frequency generation (DFG) are essential. Tunable difference frequency generation relies on high power, small linewidth, fast tunable, robust laser diode sources with excellent beam quality.With our new compact, alignment-insensitive and robust ECDL concept, we achieved an output power of 1000 mW and an almost Gaussian shaped beam quality (M²<1.2). The coupling efficiency for optical waveguides as well as single mode fibers exceeds 70%. The wavelength is widely tunable within the tuning range of 20 nm via remote control. This laser system operates longitudinally in single mode with a mode-hop free tuning range of more than 150 GHz without current compensation and a side-mode-suppression better than 50 dB. This concept is currently realized within the wavelength regime between 750 and 1080 nm.Our high powered Littman/Metcalf laser system was part of a MIR-light source which utilizes DFG in periodically poled lithium niobate (PPLN) crystals. At the wavelength of 3.3 μm we were able to achieve a high-resolution absorption spectrum of water with four different isotoplogues of H₂O components. This application clearly demonstrates the suitability of this laser for high-precision measurements. PACS 07.57.Ty; 42.55.Px; 42.62.Fi     

Continuously tunable external-cavity diode laser with a double-grating arrangement

A new external-cavity diode laser system based on an extended version of the Littman configuration is investigated. In our laser system the tuning mirror is replaced with a second grating mounted at the Littrow angle. This double-grating design provides a smaller passive bandwidth than the grating-mirror configuration, which is used to compensate for the large angle-of-incidence-dependent losses of the grazing-incidence grating. This results in a broader continuous tuning range with an improved mode stability. Because two laser diodes, emitting at 820 and 775 nm, respectively, are used, the external-cavity laser is continuously tunable without mode hops across 35 nm at 820 nm and 27 nm at 775 nm. Such a laser was used to measure the absorption lines of the oxygen A band around 762 nm. The complete R - and P -rotational branches of the b summation operator(g)(1) (+)(nu(??)=0)?X (3) summation operator(g)(-)(nu (?)=0) transition were recorded in a single-wavelength scan.     

Continuous tuning of an electrically tunable external-cavity semiconductor laser

We propose and demonstrate a novel approach to achieving rapid and phase-coherent continuous broadband tuning of a single-mode external-cavity semiconductor laser. Two internal acousto-optic devices control the angle of incident light on a diffraction grating and the effective round-trip phase electronically. Although the present implementation derives the phase from a long delay line and is not yet mode-hop free, the new approach lends itself to fully electronic control.     

Efficient skew-angle cladding-pumped tunable narrow-linewidth Yb-doped fiber laser

A skew-angle cladding-pumped tunable Yb-doped fiber laser is presented. The laser was tunable over more than 30 nm, from 1022 to 1055 nm, by employing a volume Bragg grating in a retroreflector configuration as one of the cavity delimiters. Output powers in excess of 4.3 W were recorded with a spectral bandwidth of 5 GHz and an M(2) value below 1.3 over the whole tuning range.     

Er^3＋／Yb^3＋掺杂全光纤环形激光器

本文报道利用Er~(3+)/Yb~(3+)掺杂单模光纤首次研制成功的环形谐振腔结构的可调谐(调谐范围宽于70nm)全光纤激光器的设计原理及其实验结果.     

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.     

Widely tunable, narrow-linewidth, subnanosecond pulse generation in an electronically tuned Ti:sapphire laser

Widely tunable subnanosecond Ti:sapphire laser radiation pumped with a cw Q -switched laser-diode-pumped Nd:YAG laser has been demonstrated in a simple laser system with a configuration of variable cavity length. Laser wavelengths can be continuously tuned by adjustment of the rf of an intracavity acousto-optic tunable filter with a computer through the whole range of the laser gain. During tuning of the whole spectral range, there is no need to realign any optics in the laser, except for moving the mirror to track the change of the rf. The peak powers of the output pulses at a pump level of 300 mW are comparable with those of conventional tunable picosecond Ti:sapphire lasers at a cw pump level of almost 10 W.