Abstract

An optical square-wave source is useful for applications in optical communication, optical computing, and signal processing. To date, most techniques for generating optical square-wave pulse trains rely on the use of externa1 modulators, rf oscillators, or electrical feedback schemes.¹ Passive generation of square-wave optical pulse trains has recently been demonstrated by polarization switching of diode lasers.² We report a new technique for passive generation of optical square waves based on directional switching with a diode laser array in an external cavity. Square waves with frequencies ranging to250MHz have been generated with rise times faster than 200 ps. These rise times surpass results reported for SEEDS' and polarization switching²

© 1991 Optical Society of America