GIGABIT-PER-SECOND CRYOGENIC OPTICAL LINK USING OPTIMIZED LOW-TEMPERATURE ALGAAS-GAAS VERTICAL-CAVITY SURFACE-EMITTING LASERS

We describe the design of GaAs-AlGaAs vertical-cavity surface-emitting lasers (VCSEL's) that are optimized for operation at very low tempera tures and the experimental demonstration of a free-space optical inter connect for cryogenic electronic systems using a VCSEL, We demonstrate high-speed modulation of the optical link at a data rate of up to 2 G b/s at 77 K, with a very low bit-error rate of <10(-13), and thermally stable operation is achieved over a wide range of cryogenic temperatu res without laser bias current compensation, Cryogenic VCSEL's with ex cellent lasing characteristics have been achieved over the entire temp erature range from 150 K to 6 K, including high output power (22 mW), high power-conversion efficiency (32%), high slope efficiency (similar to 100%), low threshold voltage (1.75 V) and current (1.7 mA), as wel l as a high-modulation bandwidth (12 GHz) for a 16 mu m diameter devic e at 80 K.