Describe the differences between the Raman-Nath and Bragg regimes for acousto-optic modulation. A modulator operating in the Bragg regime consists of a slab of lead molybdate (PbM04) with thickness 50 mm and refractive index 2.3 at 633 nm wavelength. An acoustic wave with frequency 80 MHz is launched into the slab parallel with its faces; its velocity in the material is 3.75 x 103 ms-1. At what angle must a 633 nm He-Ne laser beam be launched into the slab in order to suffer maximum deflection? What is the magnitude of the deflection and what is the frequency shift suffered by the deflected beam. Is there any amplitude change? How would you design an optical switch based on this operation?