An InP-based Vertical-Cavity Surface-Emitting Laser (VCSEL) with a liquid crystal (LC) microcell monolithically integrated on its surface for spectral tuning is investigated. Unlike tunable VCSELs integrating a movable membrane, here the physical length of the cavity remains unchanged and only the voltage applied on the LC ensures a refractive index modification for a particular polarization emitted by the VCSEL. This tunable VCSEL operates in CW at room temperature and exhibits more than 23 nm wavelength tuning around $1.55~\mu \text{m}$ at a maximum applied voltage of 20 V. The measured laser threshold around 6.5 mW is still comparable to VCSEL without LC microcell, a clear indication that the optical losses related the LC are very low. On the other hand, for this first optically pumped device, the lasing characteristics suggest that the LC birefringence is lower than expected. To assess this hypothesis, thermo-optical simulations have been conducted.

中文翻译：

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集成液晶微电池的可调谐 1550 nm VCSEL 的连续波操作

研究了一种基于 InP 的垂直腔面发射激光器 (VCSEL)，其表面上单片集成了液晶 (LC) 微电池，用于光谱调谐。与集成可移动膜的可调 VCSEL 不同，这里腔的物理长度保持不变，只有施加在 LC 上的电压才能确保 VCSEL 发射的特定偏振的折射率修改。这种可调谐 VCSEL 在室温下在 CW 模式下运行，并在最大施加电压为 20 V 时表现出超过 23 nm 的波长调谐约 $1.55~\mu \text{m}$。测得的 6.5 mW 左右的激光阈值仍可与 VCSEL 相比LC 微池，清楚地表明与 LC 相关的光损耗非常低。另一方面，对于第一个光泵浦设备，激光特性表明 LC 双折射低于预期。为了评估这个假设，已经进行了热光模拟。