Low-Threshold Continuous-Wave Operation of Electrically Pumped 1.55 μm InAs Quantum Dash Microring Lasers

Densely integrated devices on a single chip enable both complex functionality and economy of scale. With a small footprint, microcavities with self-assembled InAs quantum dashes (QDashes) use minimal real estate cost while offering full photonic functionality. Here, the first room-temperature-continuous-wave (CW) operation of electrically pumped InAs QDash microring lasers in the 1.55 μm telecom window is reported. CW lasing up to 55 °C has been achieved with a low threshold current density of 528 A/cm 2 . The ring laser has only a few unique modes with an extinction ratio over 26 dB for the primary mode. The reduced carrier diffusion length of the QDash active region suppresses the sidewall surface recombination. Feasibility of device miniaturization was demonstrated, with the lowest threshold being 3.5 mA. Since microring cavities do not require feedback mirrors, their compact size and resulting low thresholds make them the ideal candidate for an on-chip light source in optical datacom interconnects.