We present an optical modeling and characterization study of prototype ultraviolet laser diode (LD) structures grown on single-crystal AlN substrates, with focus on the reduction of modal loss caused by optical mode coupling to the absorptive layers on the p-side (i.e. p-contact and p-metal layers). The transparent AlN substrates enabled optical pumping for measuring modal loss without requiring functioning LDs. The modal loss measured in this way was in good agreement with electrically evaluated results of processed LDs, and both results were consistent with optical modeling predictions. By using 0.32 μ m thick p-side cladding, we were able to suppress the modal loss of the designed LD structure to 8.4 cm −1 , where the contribution from the absorptive p-contact layers was less than 3 cm −1 .

中文翻译：

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低光损耗UV-C激光二极管的设计与表征

我们目前对在单晶AlN衬底上生长的原型紫外激光二极管（LD）结构进行光学建模和表征研究，重点是减少由光学模式耦合到p侧吸收层（即p -接触层和p-金属层）。透明的AlN衬底使光泵浦能够测量模态损耗，而无需运行LD。以这种方式测量的模态损耗与经过处理的LD的电学评估结果非常吻合，并且两个结果均与光学建模预测一致。通过使用0.32μm厚的p侧覆层，我们能够将设计的LD结构的模态损耗抑制到8.4 cm -1，其中吸收性p接触层的贡献小于3 cm -1。