Ultralow-threshold cryogenic vertical-cavity surface-emitting laser

Data are presented characterizing a low-threshold vertical-cavity surface-e mitting laser designed for cryogenic operation, A threshold current of 12 m u A and current density of 25 A/cm(2) are obtained at 77 K with the low-los s cavity design. From 77 K to 160 K, the threshold increases linearly with temperature, but only approximately tracks the detuning of the cavity reson ance from the minimum energy transition of the quantum well. At 77 K, we es timate that the 25-A/cm(2) threshold current density is about twice that re quired for transparency.