Single-crystal electrooptic thin-film waveguide modulators for infrared laser systems

Wideband, low power electrooptic modulators of optical waveguide structure have been developed for infrared laser applications. They allow a reduction in driver power of two orders of magnitude below that of conventional devices. The modulators are composed of very thin layers of single-crystal GaAs, bounded on both sides by evaporated films of lower refractive index material: CdTe or As(2)S(3). Minimum propagation loss, measured at 10.6 microm, was less than 1 dB/cm for TE modes and less than 5 dB/cm for TM modes. A 20-pF modulator exhibited a pulse response rise time of 3 nsec and showed useful frequency response to beyond 200 MHz. The basic capability for advanced design modulators of this type to operate at 10 microm with driver powers of less than 25 mW/MHz for 50% modulation depth is shown.