Abstract

High frequency optical modulation is required in many applications in satellite communication, mm-wave distribution and phased array radar. Traditionally this is achieved by direct modulation of a semiconductor laser diode, or through the use of an external modulator. Direct modulation has been demonstrated up to 30 GHz [1] and traveling wave LiNbO₃ external modulators to beyond 40 GHz [2]. We present a modulation technique which potentially can be used at frequencies >100 GHz. We have experimentally demonstrated simulated radar pulse transmission at 40 GHz. The technique is based on the use of a low frequency external modulator to compensate for the phase noise on the beatnote of two laser diodes as shown in Fig. 1.

© 1993 Optical Society of America