Abstract

An optical beam which is intensity-modulated at terahertz (THz) rate is desirable for many applications such as wideband optical communication, heterodyne interferometry for absolute distance measurement, four-wave mixing in the laser diode, soliton pulse train generation, and THz radiation generation. Generation of modulated signal by direct modulation of a high-speed laser diode or by external waveguide modulator were limited 30 GHz [1] and 150 GHz [2], respectively. Optical generation of narrow band millimeter wave signal up to 60 GHz was demonstrated by mixing two lasers in a HEMT device [3]. Experimentally this requires precision alignment of two frequency- stabilized lasers, at least one of which is tunable. By recombining a linear chirped optical pulse through a Michelson interferometer, a tunable optical quasi-sinusoidal intensity modulation up to 1 THz but with a duty cycle of less than 0.3% was achieved recently [4], In this work we report the generation and measurement of an cw intensity-modulated optical beam at the highest modulation frequency reported to date, 7 THz.

© 1995 Optical Society of America