Acousto-optic modulators-frequency shifters with fiber leads

V.M. Epikhin1, M.M. Mazur1, A.V. Ryabinin1, P.V. Karnaushkin2, L.I. Mazur1, L.L. Paltsev1, V. N. Shorin1

1FSUE “VNIIFTRI”, Mendeleevo, Moscow region, Russia
2Perm State University, Perm, Russia

Al’manac of Modern Metrology № 3 (27) 2021, pages 104–116

Annotatuon. Acousto-optic modulators-frequency shifters based on TeO crystals with single-mode optical fibers supporting and not supporting polarization for collimated and focused light beams at radiation wavelengths of 785, 1064, 1550 nm have been developed, produced and experimentally investigated. The mechanisms of formation and methods of expanding the working band of the modulator are determined. A double-crystal acousto-optic laser emission frequency shifter with an working bandwidth of ≈ 40 MHz has been created. Single-crystal modulators based on collimated beams with a frequency band of ≈ 10 MHz are considered. A single-crystal modulator with a focused light beam with a switching time of ≈ 18 ns and an extended reception band of ≈ 40 MHz is investigated. It is shown that a light beam focusing makes it possible to implement a modulator with a minimum switching time of ≈ 2–3 ns. This value is limited by electrical breakdown of the ultrasonic wave transmitte.

Key words: hydrophone phase calibration, minimum-phase frequency response, Hilbert transform, complex fractional-rational approximation.

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