Parasitic-Free Modulation of Semiconductor Lasers

Absfract-Active-layer photomixing is a technique for modulating semiconductor lasers with nearly perfect immunity to device para-sitics. We have previously demonstrated this technique at room tem-perature 121. In this paper, we measure the intrinsic modulation re-sponse of a laser diode using this technique at temperatures as low as 4.2 K. From these measurements, the temperature dependence of im-portant dynamical parameters is determined. In addition, this pro-vides a stringent test of the active-layer photomixing technique since parasitic response is degraded, while the intrinsic response is improved for low-temperature operation. At 4.2 K, the ideal intrinsic response is measured for frequencies as high as 15 GHz despite an estimated parasitic corner frequency of 410 MHa. I