You will find mainly two achievable explanations for that effective refractive index variation upon mild irradiation: heating of your LiNbO3:Fe substrates and, As a result, of your LC while in the microchannel, and director reorientation in the electric area induced by light-weight in the LiNbO3:Fe substrates. Until a short while https://lithium-niobate-crystal51639.ampblogs.com/indicators-on-lithium-niobate-crystal-you-should-know-69338122