Cook Kevin T, Qiao Pengfei, Qi Jipeng, Coldren Larry A, Chang-Hasnain Connie J
Opt Express. 2019 Feb 4;27(3):1798-1807. doi: 10.1364/OE.27.001798.
The wavelength tuning range of a tunable vertical-cavity surface-emitting laser (VCSEL) is strongly influenced by the design of the interface between the semiconductor cavity and the air cavity. A simplified model is used to investigate the origin of the dramatic differences in free spectral range (FSR) and tuning slope observed in semiconductor cavity dominant, extended cavity, and air cavity dominant VCSELs. The differences arise from the positioning of the resonant and antiresonant wavelengths of the semiconductor cavity with respect to the center wavelength. The air cavity dominant design is realized by designing an antiresonant semiconductor cavity, resulting in a larger tuning slope near the center of the tuning range and a wider FSR toward the edges of the tuning range. The findings from the simplified model are confirmed with the simulation of a full VCSEL structure. Using an air cavity dominant design, an electrically pumped laser with a tuning range of 68.38 nm centered at 1056.7 nm at a 550 kHz sweep rate is demonstrated with continuous wave emission at room temperature. This epitaxial design rule can be used to increase the tuning range of tunable VCSELs, making them more applicable in swept-source optical coherence tomography and frequency-modulated continuous-wave LIDAR systems.
可调谐垂直腔面发射激光器（VCSEL）的波长调谐范围受到半导体腔与空气腔之间界面设计的强烈影响。使用一个简化模型来研究在半导体腔主导、扩展腔和空气腔主导的VCSEL中观察到的自由光谱范围（FSR）和调谐斜率的显著差异的起源。这些差异源于半导体腔的谐振和反谐振波长相对于中心波长的位置。通过设计一个反谐振半导体腔来实现空气腔主导的设计，从而在调谐范围中心附近产生更大的调谐斜率，并在调谐范围边缘具有更宽的FSR。简化模型的结果通过完整VCSEL结构的模拟得到了证实。采用空气腔主导设计，展示了一种电泵浦激光器，在室温下以550 kHz的扫描速率，在1056.7 nm中心处的调谐范围为68.38 nm，具有连续波发射。这种外延设计规则可用于增加可调谐VCSEL的调谐范围，使其在扫频源光学相干断层扫描和调频连续波激光雷达系统中更适用。
