Electrically Injected Mid-Infrared GeSn Laser on Si Operating at 140 K

Owing to its true direct bandgap and tunable bandgap energies,GeSn alloys areincreasingly attractive as gain media for mid-IR lasers that can bemonolithically integrated on Si. Demonstrations of optically pumped GeSn laserat room under pulsed condition and at cryogenic temperature undercontinuous-wave excitation show great promise of GeSn lasers to be efficientelectrically injected light sources on Si. Here we report electrically injectedGeSn lasers using Fabry-Perot cavity with 20, 40, and 80 micron ridge widths. Amaximum operating temperature of 140 K with lasing threshold of 0.756 kA/cm2 at77 K and emitting wavelength of 2722 nm at 140 K was obtained. The lowerthreshold current density compared to previous works was achieved by reducingoptical loss and improving the optical confinement. The peak power was measuredas 2.2 mW/facet at 77 K.