以磷化銦基材之量子井結構為半導體飽和吸收體實現1.3μm 被動式Q-開關雷射

Abstract

1.3-μm波段雷射因具有高能量密度之優點而廣泛地使用於醫療診斷、光通訊、遠距量測、腔內OPO、腔內拉曼轉換，但是以連續輸出雷射來進行使用，常常會發生熱效應導致激發光太強而無法做實際的應用。若運用Nd：YVO4晶體配合量子井結構作為飽和吸收體可產生穩定的Q-開關脈衝雷射，此設計囊括固態雷射高峰值功率、高脈衝能量的優點。目前廣為使用的被動式Q開關飽和吸收體包括有V3+:YAG、Co2+:MgAl2O4、以及半導體飽和吸收鏡（SESAMs）。然而製作半導體飽和吸收鏡過程中，於磷化銦基材上磊晶時往往因為材料之間的折射率差值過小，導致長晶時需要成長多層布拉格反射鏡的缺點。因此本篇報告將嘗試製作半導體飽和吸收體結構（SESA），對於共振腔設計與飽和吸收體的選用作深入討論。比較InGaAsP/InP與AlGaInAs/InP作為飽和吸收體的實驗成果，並針對量子井飽和吸收體的物理特性作定性研究，設計可靠度佳之1.34μm脈衝雷射。

All-solid-state Q-switched lasers at 1.3-μm wavelength are of practical importance for numerous application such as medical diagnostic, fiber sensing, distance measurements, intracavity optical parametric oscillator, intracavity Raman conversion. Because of thermal effects, CW laser can’t be used practically. If using Quantum Wells/barrier structures be absorbers for Nd:YVO4 lasers, it can produce a high peak power, high pulse energy, and stable Q-switching laser. Nowadays, the saturable absorbers for 1.3-μm lasers comprise V3+:YAG, Co2+:MgAl2O4, and SESAMs. However, the overall performance of the DBRs on InP substrates are hindered by disadvantage of small contrast of refractive indices. Despite that, the DBRs is merely an optional structure for the cavity design of the passively Q-switched lasers. In this work we present two kinds of barrier’s materials, InGaAsP QW/barrier and AlGaInAs QW/barrier structures. Using any of these respectively grown on a transparent InP substrate to be a SESA for Nd:YVO4 1.34-μm lasers. We study and compare with the two different SESAs as passively Q-switched lasers. Trying to find the physical characteristics of both and design a stable 1.34-μm laser.