Abstract

Generation of ultra-high frequency laser pulses has enormous impact to many areas in science and engineering. Two common approaches are gain switching and mode-locking. The frequency in former is intrinsically limited by the carrier relaxation frequency which is typically about 100 GHz [1]. The frequency in latter is primarily determined by the laser cavity length, and currently is 350 GHz in mode-locked edge emitting lasers [2] and 6 GHz for polarization switching vertical cavity surface-emitting laser (VCSEL) where the cavity length is limited by the thickness of a quarter wave plate [3]. In this paper, we propose polarization-switching VCSELs that can have a tunable oscillation frequency as high as severa1 terahertz. The substantial increase in frequency comes from using a new quarterwave plate made of an amorphous-silicon subwavelength transmission grating that is only one-third of the wavelength thick. The frequency tuning is provided by fabricating the waveplate and a mirror monolithically on a movable microcantilever.

© 1996 Optical Society of America