We report statistical comparisons of lasing characteristics in InAs quantum dot (QD) micro-rings directly grown on on-axis (001) GaP/Si and V-groove (001) Si substrates. CW thresholds as low as 3 mA and high temperature operation exceeding 80 °C were simultaneously achieved on the GaP/Si template template with an outer-ring radius of 50 µm and a ring width of 4 μm, while a sub-milliamp threshold of 0.6 mA was demonstrated on the V-groove Si template with a smaller cavity size of 5-μm outer-ring radius and 3-μm ring width. Evaluations were also made with devices fabricated simultaneously on native GaAs substrates over a significant sampling analysis. The overall assessment spotlights compelling insights in exploring the optimum epitaxial scheme for low-threshold lasing on industry standard Si substrates.
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 roomtemperature-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.
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