ACOUSTO-OPTIC FILTER WITH NEAR-IDEAL BANDPASS CHARACTERISTICS

摘要

An acousto-optic tunable filter (100) is provided with an acousto-optic interaction profile that results in a frequency response with near-ideal bandpass filter characteristics of near-unity transmission inside the passband and near-zero transmission outside the passband. The acousto-optic interaction profile which results in this frequency response has a phase polarity which alternates and is damped, i.e., the acousto-optic interaction profile has a damped oscillating shape. The physical structure to implement this filter comprises a pair of acoustical waveguides (110, 112) which taper toward each other at the beginning of the profile and then are spaced apart by a constant distance. A damping layer (132) or other damping structure is provided to achieve the damping characteristics of the profile.