1.3 μm InGaAsN quantum well vertical cavity surface emitting lasers on GaAs substrates

Abstract

We report characteristics of 1.3 /spl mu/m electrically pumped InGaAsN quantum well VCSELs grown on GaAs. The epitaxial structure was grown by MBE in a single growth run using in-situ optical reflectance feedback control to accurately control layer thicknesses. The top and bottom distributed Bragg reflector mirrors contained 28 and 33 periods, respectively. With the exception of a single period of the upper mirror nearest the cavity, both mirrors were doped n-type to reduce free carrier absorption losses. A reverse-biased GaAs tunnel diode provided a high-conductivity transition between n- and p-type regions of the upper mirror. Electrical and optical confinement were provided by selectively oxidized AlAs layers adjacent to the cavity. CW room-temperature lasing was obtained in these devices at wavelengths as long as 1294 nm, while pulsed lasing was obtained at wavelengths as long as 1305 nm. A side mode suppression of 28 dB is observed in devices operating CW at slightly shorter wavelengths. A maximum single mode output power of 140 /spl mu/W at 1289 nm was obtained at 20/spl deg/C and continuous wave operation was observed up to 50/spl deg/C. VCSELs operated with threshold currents varying from 1.5 to 7 mA. Equivalent threshold current densities were as low as 4 kA/cm/sub 2/. Open eye diagrams were obtained for devices driven on-wafer with pseudo-random bit sequences at 2.5 Gb/s. With modifications to the mirror design to lower the device voltage and modest improvements to the InGaAsN quality, we expect significantly improved optical and electrical performance.