Influence of the Brangg angle on the optimal energy exchange in the course of two-wave mixing in a Bi_12SiO_20 piezoelectric crystal

摘要

The problem of maximising the relative intensity of the signaloptical wave in the course of two-wave mixing was solved taking intoaccount the self-diffraction in a Bi~12Sio_20 piezoelectric crystal.The maximisation was carriedout simulaneously with respect to fourparameters: the polarisation (Ψ) and orientation (0) angles, thecrystal thickness d, and the Bragg angleρ. It was established thatthere are tow sets of optimal parameters for a Bi~12SiO_20 crystal atthe wavelength of 632.8 nm and for a Bi~12SiO_20 crystal at thewavelength of 632.8 nm and for a typical acceptor concentration of10~22 m~-3:ρ≈11deg,0≈39.1deg, Ψ≈98,85deg, d≈7.11 mm (for thefirst maximum) and ρ≈11deg, 0≈320.9,Ψ≈54.15deg, d≈7.11 (for thesecond maximum). The dependences of these optimal parameters on theacceptor concentration in the range 10~21-4 x 10~22 m~-3 were found.The mdoel proposed for two-wave mixing in the special case of a fixedBragg angle and the constant visibility approximation improved theagreement between the theoretical results and the known experimentaldata.