Optical control of an 8-element Ka-band phased array using a high-speed optoelectronic interconnect

Optical distribution of control signals in electronically steered phased array antennas is being considered. A demonstration experiment is described in which a high speed hybrid GaAs optoelectronic integrated circuit (OEIC) was used to control an eight element phased array antenna. The OEIC, which accepts a serial optical control signal as input and converts it to 16 demultiplexed parallel outputs, was used to control the monolithic GaAs phase shifters of a Ka-band patch panel array antenna. Antenna pattern switching speeds of 2.25 microsec, limited by interface circuitry, were observed

OPTICAL COCHLEAR IMPLANTS: EVALUATION OF SURGICAL APPROACH AND LASER PARAMETERS IN CATS

Previous research has shown that neural stimulation with infrared radiation (IR) is spatially selective and illustrated the potential of IR in stimulating auditory neurons. The present work demonstrates the application of a miniaturized pulsed IR stimulator for chronic implantation in cats, quantifies its efficacy, and short-term safety in stimulating auditory neurons. IR stimulation of the neurons was achieved using an optical fiber inserted through a cochleostomy drilled in the basal turn of the cat cochlea and was characterized by measuring compound action potentials (CAPs). Neurons were stimulated with IR at various pulse durations, radiant exposures, and pulse repetition rates. Pulse durations as short as 50 μs were successful in evoking CAPs in normal as well as deafened cochleae. Continual stimulation was provided at 200 pulses per second, at 200 mW per pulse, and 100 μs pulse duration. Stable CAP amplitudes were observed for up to ten hours of continual IR stimulation. Combined with histological data, the results suggest that pulsed IR stimulation does not lead to detectable acute tissue damage and validate the stimulation parameters that can be used in future chronic implants based on pulsed IR