Monolithic integration of InAs-based quantum cascade lasers on germanium

Abstract

Silicon photonics can have a major impact on the advancement of mid-IR photonics by leveraging the mature and reliable high-volume fabrication technologies already developed for microelectronic integrated circuits. Germanium, already used in silicon photonics, is a promising material for increasing the operating wavelength of Group-IV-based photonic integrated circuits beyond 8 µm and potentially up to 15 µm. High-performance InAs-based quantum cascade lasers grown on Si have been previously reported. In this work, we present InAs-based QCLs directly grown on Ge. The lasers operate near 14 µm with pulsed threshold current densities as low as 0.8 kA/cm 2 at room temperature.