Lasing from SOI-Integrated GaAsSb Nanowires via Resonator-Driven Optical Feedback

Area of Science:

• Photonics and Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Silicon photonic integrated circuits require compact on-chip light sources.
• Nanowire (NW) lasers offer a potential solution but suffer from broad emission line widths and poor frequency stability due to weak optical feedback.

Purpose of the Study:

• To integrate individual Gallium Arsenide Antimonide (GaAsSb) nanowires (NWs) onto silicon-on-insulator (SOI) racetrack resonators.
• To enhance optical feedback for NW lasers operating at silicon-transparent wavelengths.
• To improve emission line width and frequency stability of NW lasers on SOI platforms.

Main Methods:

• Transfer-printing of individual GaAsSb NWs onto SOI racetrack resonators.
• Finite-difference-time-domain (FDTD) simulations to analyze optical coupling and cavity Q factors.
• Experimental characterization of lasing emission, threshold, line width, and stability.

Main Results:

• Efficient optical coupling between the hybrid NW-waveguide mode and the fundamental TE resonator mode was simulated, with calculated Q factors > 10^4.
• Feedback-induced lasing emission was observed experimentally with a low threshold (Pth) of 8.6 ± 1.8 μJ/cm^2.
• The emission line width was reduced by over a factor of 4 at 3Pth compared to NW lasers without resonators, remaining stable below 1.8 meV up to 5Pth.

Conclusions:

• Demonstrated the successful integration of NW-based light sources onto SOI.
• Showcased that tailored resonator designs significantly improve line width control and frequency stabilization for NW lasers.
• This work paves the way for improved NW lasers in silicon photonics.