Acousto-Optical Tunable Transmissive Grating Beam Splitter
A. Dieulangarda,b,c,d, J.-C. Kastelika,b,c, S. Duponta,b,c and J. Gazaleta,b,c
aUniversité Lille Nord de France, 59000 Lille, France
bUniversité de Valenciennes et du Hainaut-Cambrésis, IEMN-DOAE, Le Mont Houy, 59313 Valenciennes Cedex 9, France
cCNRS, UMR 8520, 59650 Villeneuve d'Ascq, France
dAA Opto-electronic SA, 18, rue Nicolas Appert, 91898 Orsay, France
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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. 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 the 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 are presented as for example a spectral bandwidth from 450 nm to 550 nm with a carrier frequency f0=125 MHz.

DOI: 10.12693/APhysPolA.127.66
PACS numbers: 78.20.hb, 42.79.Jq, 43.35.Sx