<title>Efficient acousto-optically phase-matched noncollinear optical second-harmonic generation in tellurium</title>

Abstract

Two kinds of practical efficient acoustooptically phase-matched noncollinear second harmonic generation (SHG) interactions are predicted in Tellurium for the incident optical wave at 10.6µm .They are produced by two anisotropic acoustooptic. (AO)interactions in which the normal to the AO interaction plane is offset of 10° with respect to the optical (Z)a.xis . For X-propagating slow shear acoustic wave, a high AO figure of merit is predicted, presenting a low optic absorption in Tellurium. The first SHG wave is interpreted as being due to mixing of the incident optical ave and the acoustooptically scattered wave. The other SHG is observed due to mixing of the two acoustooptically scattered waves. It is shovm from absolute SHG calculations and corresponding SHG measurements previously reported in Te, that the nonlinear optical coefficient which governs these high efficiency SHG interactions is d = 65x10-11m/V . 11 Tbe corresponding SHG efficiencies of these anisotropic diffraction geometries are about x6 and x 5 times respectively larger than the previously reported AO phase-matched noncollinear SHG in Te, for the same input and acoustic power. A comparison is made with the next best ex<2 materials like the cbalcogenide compounds (Tl.3Asse3), proustite (AgGaSe3); Gallium .Arsenic (GaAs) and CdGeAs2.