Gallium arsenide (GaAs) metal–semiconductor–metal (MSM) photodetectors have unique properties including high-bandwidth, linearity, and biphase response that make them suitable as mixers and programmable weights for microwave and communications applications. An optical technique for microwave single-sideband modulation that uses GaAs MSM photodiodes as mixers is reported. It uses MSM Schottky photodiodes formed in a GaAs/Al<sub>0.3</sub>Ga<sub>0.7</sub>As materials system to detect microwave in-phase and quadrature signals on optical carriers. Modulation of the photodetector bias voltages results in a single-sideband modulation of the microwave signal. Radio frequency and undesired-sideband suppression of 36 and 27 dB, respectively, were achieved. The optical wavelength was 850 nm, and the bandwidth of the photodetectors was ≥29 GHz.
[Optical Society of America ]
(040.5160) Detectors : Photodetectors
(230.5160) Optical devices : Photodetectors
(230.5170) Optical devices : Photodiodes
(250.0250) Optoelectronics : Optoelectronics
(350.4010) Other areas of optics : Microwaves
Gordon Wood Anderson, L. Eugene Chipman, Francis J. Kub, Doewon Park, Michael Y. Frankel, Thomas F. Carruthers, John A. Modolo, Karl D. Hobart, and D. Scott Katzer, "Gallium Arsenide Metal–Semiconductor–Metal Photodiodes as Optoelectronic Mixers for Microwave Single–Sideband Modulation," Appl. Opt. 37, 28-33 (1998)