US Patent 7911395 Optically driven antenna

There is provided an optically driven, transmitting and receiving antenna transformable into an electrically invisible antenna when inactive, including a light source, a semiconductor wafer illuminatable by the light source and a microwave source or sensor. The wafer has a surface for forming optically induced plasma or electron hole concentration, assuming a spatial and temporal pattern defined by a light beam impinging thereon. Upon the wafer being exposed to the light beam having a power level sufficient for creating a dense plasma or electron hole concentration in the wafer, the wafer becomes reflective to microwaves, and returns to transparency when light from the light source is turned off.