GaSb based midinfrared equilateral-triangle-resonator semiconductor lasers

Abstract

Theoretical calculations of the mode characteristics of an equilateral-triangle resonator (ETR) with a 10μm cavity side length show that the fundamental mode, with longitudinal mode index of 25, has a wavelength of 2.185μm and a longitudinal mode separation of 100nm. This mode has a quality factor (∼2×105) that is much larger than the first (∼5×104) and second (∼3×104) order modes, indicating that single fundamental mode lasing should be accessible over a broad wavelength tuning range. An electrically injected ETR based on this design is fabricated from an InGaAsSb∕AlGaAsSb∕GaSb, graded-index separate-confinement heterostructure, laser diode wafer with a 2.1μm emission wavelength. This device achieved single mode, continuous wave operation at 77K with a threshold current of 0.5mA and a single mode wavelength tuning range of 3.25nm, which is accomplished by varying the injection current from 0.5to6.0mA.