通过方位角光栅实现高速低阈值III-V/硅量子点微环激光器的单模控制
Single-Mode Control of High-Speed and Low-Threshold III-V/Si Quantum Dot Microring Lasers via Azimuthal Gratings
AI总结：
该研究通过在硅环中引入方位角光栅，实现了III-V/硅量子点微环激光器的单模控制，其边模抑制比达37.9 dB，阈值电流低，可作为数据通信等领域的实用光源模块。
AI中文摘要：
混合III-V/硅量子点微环激光器是紧凑、节能的O波段光源，但其回音壁腔天生为多模且双向，会产生不稳定的模式跳变，与密集波分复用不兼容。我们表明，在硅环中刻蚀方位角光栅——仅需一次光刻自由度——可将该多模腔转换为波长寻址的单模光源。耦合模分析从第一性原理推导出角动量选择规则，表明内壁波纹将简并的反向传播对替换为具有不等辐射损耗的对称和反对称驻波超模。在二阶布拉格条件下，反对称模式受对称性保护，在恰好一个方位角阶处产生高品质因子状态；有限元模拟证实了这一点，并确定光栅深度是损耗工程的主要调控参数。在100毫米绝缘体上硅平台上自制的器件保持单个纵模，边模抑制比为37.9 dB，且具有连续、无跳变的调谐性能，同时发射波长在腔负载变化两倍时保持固定，该负载由光刻设定而非增益峰值。由于光栅将激射波长与量子点增益解耦，失谐成为掩模级设计变量，可设定阈值电流最小的温度，在50°C附近达到1.95 mA。结合超过37 dB的边模抑制和多吉赫兹直接调制，这些激光器是数据通信和共封装光学中级联、波长寻址发射机阵列的实用构建模块。
英文摘要：
Hybrid III-V/silicon quantum-dot microring lasers are compact, energy-efficient O-band sources, but their whispering-gallery cavities are inherently multimode and bidirectional, producing unstable mode hopping that is incompatible with dense wavelength-division multiplexing. We show that an azimuthal grating patterned into the silicon ring - a single lithographic degree of freedom - converts this multimode cavity into a wavelength-addressed, single-mode source. A coupled-mode analysis derives the angular-momentum selection rule from first principles and shows that the inner-wall corrugation replaces the degenerate counter-propagating pair with symmetric and anti-symmetric standing-wave supermodes of unequal radiative loss. At the second-order Bragg condition the anti-symmetric mode is symmetry-protected, yielding a high-quality-factor state at exactly one azimuthal order; finite-element simulations confirm this and identify grating depth as the primary loss-engineering handle. Devices fabricated in-house on a 100 mm silicon-on-insulator platform hold a single longitudinal order with a side-mode suppression ratio of 37.9 dB and continuous, hop-free tuning, while the emission wavelength stays fixed across a factor-of-two change in cavity loading, set lithographically rather than by the gain peak. Because the grating decouples the lasing wavelength from the quantum-dot gain, the detuning becomes a mask-level design variable that sets the temperature of minimum threshold current, reaching 1.95 mA near 50 °C. Combined with side-mode suppression beyond 37 dB and multi-gigahertz direct modulation, these lasers are practical building blocks for cascaded, wavelength-addressed transmitter arrays in data communication and co-packaged optics.
