Optically Tunable Millimeter-wave Attenuator Based on Layered Structures

A new type of optically controllable, millimeter-wa e ( ) ( ) ( ) MMW attenuator based on high-resisti ity high-R silicon Si wafers and a layered structure is de eloped. A high-R float-zone Si wafer is a lossless dielectric material at microwa e frequency without optical excitation. When an Si wafer is optically excited, free carriers are generated, and the Si wafer becomes a lossy dielectric. This property is combined with a layered structure to de elop a simple optically tunable MMW attenuator. A more than 20 dB attenuation with a 10% bandwidth of the center frequency is obtained at W-band. The proposed structure is useful for de eloping low-cost attenuators and switches in the MMW region. 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 9 13, 2000.