CRYOGENIC OPERATION OF ALGAAS-GAAS VERTICAL-CAVITY SURFACE-EMITTING LASERS AT TEMPERATURES FROM 200 K TO 6 K

We demonstrate for the first time the CW performance of AlGaAs-GaAs ve rtical-cavity surface-emitting lasers (VCSEL's) at cryogenic temperatu res from 6 K to 200 K, By detuning the cavity mode with respect to the gain peak so that optimum de lasing operation is achieved at similar to 100 K, we find that this optimum lasing performance can be maintain ed down to temperatures as low as 6 K. Across a broad range of tempera tures from 200 K to 6 K, the minimum threshold current of a 16-mu m di ameter VCSEL stayed below 4 mA, while its -3-dB modulation bandwidth i ncreased by about 70% to 11 GHz at 6 K, and the external slope efficie ncy is greater than 70%.