Direct optical phase shifter for phased-array systems

An all optical circuit in GaAs/AlGaAs for control of phased-array systems using a single photonic integrated circuit chip has the potential for high performance control of phased-array system from a small, lightweight, package. Such a circuit based exclusively on combinations of reverse-biased optical phase modulators, waveguide interconnects, corner reflectors, and power splitter combiners with optical-fiber output to the antenna elements has been designed at Sandia National Laboratories. This paper presents some basic features of optical phase modulators for photonic circuit applications and provide relevant performance data as achieved to date. Current structures have been shown to operate with a 76.5 degree/V-mm figure of merit at 1.06 micron and losses as low as 2/cm. A digital phase shifter to allow direct digital control of phased arrays is also proposed and demonstrated.