The Fabry-Perot Electrooptic Modulator

Light modulators, operating at microwave frequencies, have been receiving considerable attention. Recently, Kaminow, 1 using the Pockel's effect in K D P , produced usable amounts of modulation at an X-band frequency. The modulator was operated on a pulse basis because of the large power dissipated per unit volume in the KDP. One solution for the problem of heat dissipation as discussed by Kaminow 1 and others, 2 requires careful matching of the phase velocity of the microwaves to the light velocity in the electrooptic material, and calls for the construction of a long modulator. The resulting large coherence volume decreases the power dissipation to a value low enough to allow continuous operation. The mechanical difficulties, as well as the transmission loss associated with long rods, among other problems, has made the realization of such low power modulators impractical. On the other hand, the advent of sources of monochromatic light energy, such as the optical maser, provides alternatives not available with conventional light sources. 155