The search for a silicon (or germanium)-based laser has been an important focus in photonics for many years. As both silicon (Si) and germanium (Ge) are known to be indirect semiconductors, a Si-compatible light emitter was still lacking. Recently, we have experimentally shown that hexagonal silicon-germanium (hex-SiGe) features a direct bandgap and efficiently emits light [1]. 

Here, we show indications for lasing in a hex-SiGe NW on a SOI microstadium cavity. The dashed curve is the spectrum at low excitation density for an ensemble of hex-SiGe NWs. The fundamental transition is centered at 2050 nm. The peak at 1700 nm is from the GaAs substrate. The full curve is the spectrum of a single NW on a stadium cavity recorded at a high laser fluence of 0.6mJ/cm2. We observe that the spectrum has narrowed down to a single peak with a FWHM of 11 nm, limited by the monochromator resolution. Moreover, the sharp peak is observed at the high energy tail of the fundamental transition. This sharp spectrum is generally considered as proof for lasing.

References

[1] E. M. T. Fadaly et al., Nature, 2020, vol. 580, no. 7802, pp. 205–209.