Dynamic modulation of refractive index in Y-X LiNbO3 slab through lamb wave
Refractive index contrast generation, due to induced modulation of refractive index in Y-X LiNbO3 slab by Lamb wave has been studied theoretically. Acoustic frequency and corresponding wavelength is chosen to excite S0 Lamb mode in 400nm thick slab using Rayleigh-Lamb frequency relations. Propagation of Lamb wave produces strain in the slab and modulates refractive index. This modulation is responsible to produce refractive index contrast. Sinusoidal variation of refractive index has been found in slab with a period equals to wavelength of excited Lamb mode. The obtained maximum variation in refractive index along X is of order 0.0166 with respect to unperturbed value 2.28 in 400nm thick Y-X LiNbO3 slab at 5GHz Lamb wave frequency. These contrast variations along both X and Y directions decrease with increase in slab thickness.