Acousto-optic bragg cell

Abstract

A Bragg cell device for use as a tap in optical systems. In one embodiment an acoustic transducer is secured to a surface of an acoustic transmission medium, which is adjustably secured in hertzian contact with a surface of a waveguide. Bulk acoustic waves at frequencies above about 1 GHz are transmitted from the transducer through the transmission medium into the waveguide along a propagation path wherein the acoustic wavefronts intersect a light path in the waveguide at an angle which satisfies Bragg conditions, producing deflection of light out of the light path. Preferably, the transmission medium is also an optical conductor and is oriented upon the waveguide to receive the deflected light and transmit it to a polished optical window on the transmission medium. A grating transducer is secured on the transmission medium to detect acoustic signals reflected in the transmission medium. During position adjustment of the transmission medium and the waveguide, proper positioning is confirmed by a detected decrease in reflected acoustic signals, indicating the signals are entering the waveguide. In another embodiment, a grating transducer is deposited directly on a surface of a waveguide in a configuration to launch acoustic waves into the waveguide at an angle necessary to produce deflection of light from optical paths in the waveguide. When the waveguide comprises an optical fiber, the grating transducer conforms to the curvature of the fiber surface, thereby focusing acoustic signals from the transducer onto the fiber core.