Optical gain and absorption of 1.55 μm InAs quantum dash lasers on silicon substrate

Abstract

This Letter reports on the temperature-dependent optical gain and absorption features, including the quantum confined Stark effect, of an InAs/InGaAs quantum-dash laser directly grown on a (001) Si substrate, with the lasing wavelength within the range of 1.5–1.6 μm. The maximum optical net gain was 22 cm−1, and the internal optical loss was ∼–17 cm−1 at 20 °C. Measurements as a function of injection level indicate that while the required current densities are still high, the intrinsic performance is significantly better than that of similarly operated InAs quantum dots operating at 1.3 μm, and further effort on growth could be made to reduce the internal optical losses and non-radiative current density. Optical modal absorption spectra were measured as a function of reverse bias from 0 V to 6 V, and a 40 nm redshift was observed in the absorption edge due to the quantum confined Stark effect, suggesting potential applications of these materials in electro-absorption modulators grown on silicon.