A HIGH-SPEED FREE-SPACE TRAVELING-WAVE PHOTODETECTOR

We present and experimentally demonstrate a traveling wave photodetect or adapted to the detection of optically carried microwave signals. Th e synchronous propagation of the detected modulated laser beam with th e photogenerated microwave signal is obtained with a diffraction grati ng. This concept provides a large detection volume which could be suit able for the optical generation of high power/large dynamic range micr owave signals. The operating principle of the device is detailed and e xperimentally demonstrated, over a 0-5 GHz bandwidth, using a coplanar metal-semiconductor-metal waveguide on a GaAs molecular beam epitaxia lly grown layer. (C) 1998 American Institute of Physics. [S0003-6951(9 8)03710-3].