Semiconductor nanowire (NW) lasers are nanoscale coherent light sources that exhibit a small footprint, low-threshold lasing characteristics, and properties suitable for monolithic and site-selective integration onto Si photonic circuits. An important milestone on the way toward novel on-chip photonic functionalities, such as injection locking of laser emission and all-optical switching mediated by coherent optical coupling and feedback, is the integration of individual, deterministically addressable NW lasers on Si waveguides with efficient coupling and mode propagation in the underlying photonic circuit. Here, we demonstrate the monolithic integration of single GaAs-based NW lasers directly onto lithographically defined Si ridge waveguides (WG) with low threshold power densities of 19.8 μJ/cm² when optically excited. The lasing mode of individual NW lasers is shown to couple efficiently into propagating modes of the underlying orthogonal Si WG, preserving the lasing characteristics during mode propagation in the WG in good agreement with Finite-Difference Time-Domain (FDTD) simulations. Using a WG structure with a series of mask openings along the central mode propagation axis, we further illustrate the out-coupling properties of both spontaneous and stimulated emission and demonstrate propagation of the lasing mode over distances >60 μm, despite absorption in the silicon dominating the propagation losses.

中文翻译：

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现场选择性生长的III–V纳米线激光器的相干发射直接耦合到近端硅波导中

半导体纳米线（NW）激光器是纳米级相干光源，具有较小的覆盖区，低阈值的激光发射特性以及适合于单片和位置选择性集成到Si光子电路的特性。实现新颖的片上光子功能（例如由相干光耦合和反馈介导的激光发射的注入锁定和全光切换）的一个重要里程碑是，在具有有效耦合的Si波导上集成单个可确定寻址的NW激光器在底层光子电路中的传播和模式传播。在这里，我们演示了将单个基于GaAs的NW激光器直接集成到光刻定义的Si脊形波导（WG）上，其低阈值功率密度为19.8μJ/ cm ²当光学激发时。单个NW激光器的激光模式显示为有效耦合到下面的正交Si WG的传播模式，与有限时域（FDTD）模拟很好地保持了WG在模式传播期间的激光特性。使用沿中心模式传播轴具有一系列掩膜开口的WG结构，我们进一步说明了自发发射和受激发射两者的输出耦合特性，并展示了激光模式在> 60μm距离上的传播，尽管在硅中占主导地位传播损失。