Infrared electrooptic waveguides

Design, fabrication and performance of low-loss infrared optical waveguides suitable for broad-band electrooptic modulation of CO2lasers are described. For high-power applications, a two-dimensional tapered ridge waveguide, which is fabricated by the ion-beam milling technique and bonded on a copper heat sink, is found to be the best choice. With a 15-W CO2laser of a beam size ≤ 1 mm in diameter, we have experimentally obtained 78 percent power coupling in and out of a tapered waveguide, while keeping the electrode loss to a minimum value of 0.05 cm-1and eliminating beam distortion. These bonded-down GaAs thin-slab modulators on copper substrates, with typical dimensions of 1 cm wide, 4.5 cm long, and 25 μm thick, have been tested with intense optical and microwave fields at a combined power input up to 100 W.