Electro-optic modulator with improved acousto-optic suppression, heat transfer and mechanical support

摘要

An improved electro-optic moduator device is disclosed which provides strain-free mounting of an electro-optic crystal within a housing assembly and suppression of acousto-optic effects within the crystal. An acoustic matching liquid having an acoustic impedance substantially matching the acoustic impedance of the electro-optic crystal is disposed within the housing enveloping longitudinally the crystal. The acoustic matching liquid effectively suppresses the acousto-optic resonances within the crystal by coupling the acoustic energy out of the crystal into the liquid. The liquid enveloping the crystal also provides a uniform heat conduction path for minimizing thermal gradient variations and the resulting thermally induced strain within the crystal. A zinc oxide suspension in silicone oil is an exemplary acoustic matching liquid for gallium arsenide or cadmium telluride crystals. In one embodiment the acoustic matching liquid has a consistency of a slurry capable of being recirculated through the housing to improve the heat transfer characteristics of the liquid. In a further embodiment an acoustic absorber, disposed in a spaced apart relationship about the crystal, is adapted for absorbing acoustic energy transmitted through the liquid. An elastomeric seal at each end of the crystal provides a liquid-tight seal between the housing and the crystal to maintain the liquid within the housing and provides a soft-mounting structure to minimize thermally and mechanically induced strain within the crystal.