We present a tunable transmissive grating beam splitter for multiple laser line separation based on acousto-optic
interaction in tellurium dioxide. Acousto-optic devices are well known for light modulation, frequency shifting, filtration
or deflection. For a deflector, the incident light beam is monochromatic and the angular deviation is proportional to the
ultrasonic frequency excursion. For a tunable filter, the selected wavelength is determined by the ultrasonic frequency.
Several wavelengths may be simultaneously diffracted using several associated ultrasonic frequencies and all the
diffracted beams have the same angular deviation. Unlike the classical operating modes of acousto-optic devices, we
consider the simultaneous diffraction of several optical wavelengths by a single ultrasonic frequency. The device is
based on Bragg anisotropic interaction in the specific “Tangent Phase Matching” configuration. The acousto-optic
interaction takes place with a single ultrasonic frequency and the diffraction efficiency remains high over a wide optical
spectral range. The different diffracted beams are then angularly well separated, due to the slow velocity of the ultrasonic
wave propagating in tellurium dioxide. The optical bandwidth is directly related to the operating ultrasonic frequency.
Numerical calculations were carried out to determine the main parameters of the device: operating ultrasonic frequency,
optical bandwidth, tunability range, crystalline cut and transducer length. A practical device has been designed for
visible spectrum. Experimental results will be presented as for example a spectral bandwidth from 450 nm to 550 nm
with a RF carrier frequency f = 125 MHz.
In this paper, we present a bifrequency acousto-optic polarization splitter (BAOPS) used to select independently the two
polarization states of an arbitrary polarized input beam with two acoustic carriers. We make use of a dual frequency
anisotropic interaction in the crystal, two acoustic waves diffract the optical beam, each frequency being tuned for
interaction with only one of the beam polarizations. We explain how this double interaction is made possible by a proper
cut of the paratellurite crystal and for a chosen launching angle of the input beam. In a first part we derive the theory
underlying the acousto-optic interaction and the design of the paratellurite device. Then we describe our experimental
setup, show some experimental results and discuss them.