r and the resolvable spots. 10.4. Harris filter. Consider the interaction of a longitudinal acoustic wave and an optical wave which are both propagating along the x axis of a LINDO, crystal [see Fig. 10-12(a)]. (a) Show that the strain field can be written S - oooooh exp[i(&t - Kx)], where S, is the only nonvanishing strain component. (b) The point-group symmetry of LiNbO, crystal is 3m. From Table 9.1 and Eq. (9.1-3), show that the change in the optical impermeability induced by the strain field is Pus, 0 An - 0 P12S, P14S, expli(St - Kx)]. 0 PHS, P13SI Therefore, the Bragg coupling between the y- and z-polarized waves occurs via the photoelastic coefficient p14 (= P41). (c) Show that the