Hybrid Si-GaAs photonic crystal cavity for lasing and bistability

TL;DR

This paper presents a hybrid silicon-GaAs photonic crystal cavity design that enables efficient light confinement and interaction with quantum dots, facilitating low-power lasing and optical bistability at telecom wavelengths.

Contribution

It introduces a novel 3D FDTD-designed hybrid Si-GaAs cavity that controls mode coupling, enabling on-chip light sources and nonlinear photonic functionalities.

Findings

Achieved cavity mode confinement in GaAs without direct patterning.

Demonstrated low-threshold lasing at 156 nW.

Realized optical bistability at 18.1 μW.

Abstract

The heterogeneous integration of silicon with III-V materials provides a way to overcome silicon's limited optical properties toward a broad range of photonic applications. Hybrid modes are a promising way to make heterogeneous Si/III-V devices, but it is still unclear how to engineer these modes to make photonic crystal cavities. Herein, using 3D finite-difference time-domain simulation, a hybrid Si-GaAs photonic crystal cavity design enables cavity mode confinement in GaAs without directly patterning that operates at telecom wavelengths. The hybrid cavity consists of a patterned silicon waveguide nanobeam that is evanescently coupled to a GaAs slab with quantum dots. We show that by engineering the hybrid modes, we can control the degree of coupling to the active material, which leads to a tradeoff between cavity quality factor and optical gain and nonlinearity. With this design, we demonstrate a cavity mode in the Si-GaAs heterogeneous region, which enables strong interaction with the quantum dots in the GaAs slab for applications such as low-power-threshold lasing and optical bistability (156 nW and 18.1 ${\mu}$W, respectively). This heterogeneous integration of an active III-V material with silicon via a hybrid cavity design suggests a promising approach for achieving on-chip light generation and low-power nonlinear platforms.