【作者】 王浩；

【导师】 袁孝；

【作者基本信息】 苏州大学 ， 光学工程， 2012， 硕士

【摘要】 半导体激光阵列（LDA）以其体积小、效率高和易集成等优点广泛应用于通信、科研、工业、医疗、泵浦固体激光器等诸多领域。由于LDA峰值波长随温度漂移、光谱线宽较宽等缺陷，严重制约了其在工业、科研及作为高功率激光泵浦源等领域的应用。Bragg体光栅作为外腔反馈元件可以实现LDA的波长稳定及线宽窄化，本论文重点针对Bragg光栅反射率对外腔半导体激光阵列输出特性的影响展开了理论和实验研究：利用Kogelnik耦合波理论研究了Bragg体光栅的衍射特性，分析了光栅厚度、空间频率和折射率调制度对光谱选择特性和衍射效率的影响。利用激光速率方程研究了光栅外腔LDA的工作特性如阈值增益和输出线宽等，结果表明外腔半导体激光器的工作特性主要受到光栅反射率及半导体激光阵列输出面反射率的影响，外腔LDA系统实现光谱稳定的范围与Bragg光栅反射率成正比，与LDA输出面反射率成反比，外腔的引入显著压缩LDA的光谱线宽以及降低LDA阈值。。开展了Bragg体光栅稳定LDA输出光谱和光谱窄化实验研究，采用光线追迹法分析了准直系统对反馈耦合效率的影响。实验结果表明LDA中心波长有效锁定，输出线宽明显窄化。针对808nm外腔半导体激光阵列，可将光谱线宽压缩至0.2nm，输出功率达36W以上的激光输出，外腔效率为84.8%；针对852nm半导体激光阵列，可将光谱线宽压缩至0.17nm，输出功率达36W以上的激光输出，外腔效率为87.9%。研究了外腔半导体激光阵列输出光谱特性与Bragg体光栅反射率的关系。结果表明：Bragg体光栅反射率的增加可以有效抑制半导体激光阵列的内腔模式，提高输出光谱对比度，同时获得更窄的光谱线宽，但会造成激光器斜率效率降低。通过分析斜率效率下降的原因，结合实验数据表明光栅反射率在25%~35%时，既可以获得优异的光谱特性又可以保证较高的外腔效率。更多还原

【Abstract】 Due to the small size, high efficiency and easily integrated, etc., laser diode array(LDA) have applied in many fields such as communication, medical laser, research anddevelopment, pumping solid-state lasers and others. Because of the drawback such aswide line-width and central wavelength drifts with temperature, the further developmentin industry R&D and pumping other lasers is restricted. Theoretical and experimentalstudy of wavelength stabilization and line-width narrowing of external-cavity laser diodearray based on volume Bragg grating (VBG) has been studied in this thesis. Theinfluence of spectral selectivity and peak diffraction efficiency of VBG with differentgrating parameters, such as thickness, period and refractive index modulation, isanalyzed with Kogelnik coupled-wave theory. The operating characteristics of external-cavity LDA such as output line width and threshold gain are analyzed with rate equations.The results show that the operating characteristics are influenced by the reflectivity ofVBG and LDA front facet. The spectral stabilization and photon density of the externalresonator is proportional to the reflectivity of Bragg gratings, but inversely proportionalto the reflectivity of the LDA front facet. The spectral linewidth is obviously narrowedand the the threshold of the LDA is decreased with the external Bragg grating resonator.The spectral stabilization and spectral narrowing experiment with the external-cavity LDA with volume Bragg grating was studied. The influence of fast-axis-collimation on coupling efficiency was studied with ray-tracing method. The resultsindicate that the central wavelength of LDA was locked efficiently and line-width wasnarrowed sharply under the effect of VBG external-cavity. For808nm LDA, an outputpower of24.8W is obtained with the linewidth down to0.18nm, which corresponds to the efficiency of82.6%. For852nm LDA, an output power of20.54W is obtained withthe linewidth down to0.17nm, which corresponds to the efficiency of86.6%.Thedependence of of spectral characteristics of external cavity LDA with the reflectivity ofVBG was studied. The results show that the increasing of VBG reflectivity can inhibitthe intra-cavity mode, enhance the spectral contrast and narrow the line-width, whilethe slope efficiency of the external LDA was reduced. Combined the experimental resultsand theoretical analysis, the VBG reflectivity between25%and35%is suitable forhigh external-cavity efficiency and excellent spectral characteristics.更多还原