Ultrasonic signal synthesis for acousto-optical white light filtering with arbitrary spectral transmission function

Konstantin Yushkov , Vladimir Molchanov , Sergey Chizhikov

Acousto-optical filtering of broadband light is based on Bragg phase matching between light and single-frequency ultrasound in crystals with strong anisotropy of acoustic and optical properties. Conventionally, acousto-optical method provides easy tuning of transmitted optical wavelength, but the shape of transmission function can not be adaptively adjusted. We developed a novel algorithm for feeding acousto-optic tunable filters that provides possibility for arbitrary transformation of transmission function. The method is based on linear frequency modulation of permittivity tensor of the crystal by ultrasound. Precise shaping of transmission function was obtained with the help of amplitude modulation and nonlinear phase modulation. Quasicollinear filter on the base of paratellurite crystal was designed and fabricated for experimental verification of the algorithm. The device was operating with 80 % diffraction efficiency for radiation with the bandwidth of 150 nm centered at 800 nm, and spectral resolution was higher than 10 cm$^{-1}$. Experiments with broadband femtosecond laser oscillator demonstrated variable band-pass and notch filtering as well as multi-window transmission function.

Mots clés: acousto-optics; paratellurite

Domaines: Acoustique [physics.class-ph]

Konstantin Yushkov, Vladimir Molchanov, Sergey Chizhikov. Ultrasonic signal synthesis for acousto-optical white light filtering with arbitrary spectral transmission function. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00811046⟩