Acousto-Optic Tunable Filters

Abstract

The most widespread uses of the acousto-optic interaction have been those in which the RF signal driving the transducer is made to control in some fashion a fixed optical beam, generally from some type of laser. Historically, the collinear Acousto-Optic Tunable Filters (AOTF) was first to be reported, and the concepts central to its operation will be used to introduce many of the important features. The key development of the noncollinear AOTF was made by Chang which resulted in an AOTF with a large angular aperture. An important limitation that must be kept in mind for collinear AOTF design is the effect of acoustic attenuation, especially at short wavelengths where the tuning frequencies are high. Several of the beam introduction and extraction configurations reported for the collinear AOTF are summarized. The noncollinear AOTF offers an excellent approach to providing the rapid spectral scan along with the desired light polarization properties.