Low-threshold optically pumped lasing in highly strained Ge nanowires

TL;DR

This paper reports the first demonstration of low-threshold, optically pumped lasing in highly strained germanium nanowires, advancing the development of integrated photonic circuits with group IV lasers.

Contribution

It introduces a novel low-threshold germanium nanowire laser under uniaxial tensile strain, overcoming previous high-threshold limitations of group IV lasers.

Findings

Achieved multimode lasing at 83 K with a threshold of ~3.0 kW/cm^2

Demonstrated strain-induced bandstructure modification enabling lasing

Paved the way for CMOS-compatible integrated photonic lasers

Abstract

The integration of efficient, miniaturized group IV lasers into CMOS architecture holds the key to the realization of fully functional photonic-integrated circuits. Despite several years of progress, however, all group IV lasers reported to date exhibit impractically high thresholds owing to their unfavorable bandstructures. Highly strained germanium with its fundamentally altered bandstructure has emerged as a potential low-threshold gain medium, but there has yet to be any successful demonstration of lasing from this seemingly promising material system. Here, we demonstrate a low-threshold, compact group IV laser that employs germanium nanowire under a 1.6% uniaxial tensile strain as the gain medium. The amplified material gain in strained germanium can sufficiently surmount optical losses at 83 K, thus allowing the first observation of multimode lasing with an optical pumping threshold density of ~3.0 kW cm^-^2. Our demonstration opens up a new horizon of group IV lasers for photonic-integrated circuits.