Hybrid Integration of Laser Source on Silicon Photonic Integrated Circuit for low-cost Interferometry Medical Device

摘要

The cost-effective integration of laser sources on Silicon Photonic Integrated Circuits (Si-PICs) is a key challenge to realizing the full potential of on-chip photonic solutions for telecommunication and medical applications. Hybrid integration can offer a route to high-yield solutions, using only known-good laser-chips, and simple free-space micro-optics to transport light from a discrete laser-diode to a grating-coupler on the Si-PIC. In this work, we describe a passively assembled micro-optical bench (MOB) for the hybrid integration of a 1550nm 20MHz linewidth laser-diode on a Si-PIC, developed for an on-chip interferometer based medical device. A dual-lens MOB design minimizes aberrations in the laser spot transported to the standard grating-coupler (15μm × 12μm) on the Si-PIC, and facilitates the inclusion of a sub-millimeter latched-garnet optical-isolator. The 20dB suppression from the isolator helps ensure the high-frequency stability of the laser-diode, while the high thermal conductivity of the A1N submount (30(W/m. ℃), and the close integration of a micro-bead thermistor, ensure the stable and efficient thermo-electric cooling of the laser-diode, which helps minimise low-frequency drift during the approximately ~ 15s of operation needed for the point-of-care measurement. The dual-lens MOB is compatible with cost-effective passively-aligned mass-production, and can be optimised for alternative PIC-based applications.