Semiconductor crystals exhibit very high Figures of Merit forAcousto-optic applications at photon energies close to their band gaps. In semiconductor superlattices one can also exploit a Fabry-Perot effect whose resonances occur near the stop bands. These periodic structures allow light retrodiffraction by ultrasonic waves. It is shown that the use of semiconductor crystals and superlattices as interaction materials permits the conception of fast broadband acousto-optic deflectors and modulators.

Acousto-optical properties of GaAs and InP are thoroughly investigated for photon energies tending to the band gap from below, and the whole set of photoelastic constants is determined as a function of the wavelength λ for λ≤1.06 μm. Figures of merit as high as 1200 times those of silica have been measured. It is shown how one can take advantage of the near-resonance acousto-optical properties of GaAs and InP in device design, in spite of the optical absorption. Such devices could be broadband, fast, compact, and insensitive to light polarization and may involve other direct-gap III-V crystals, adapted to the laser radiation.

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Optical, acoustical and near-resonance acousto-optical properties of GaAs and InP an investigated and several high performance devices are achieved using these crystals. It is shown that this study can be extended to other direct-gap semiconductors of Ill-V and il-VI elements to match the optical sources in a large range of available light wavelengths.

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