You will find generally two doable explanations for the effective refractive index variation on gentle irradiation: heating with the LiNbO3:Fe substrates and, As a result, of the LC within the microchannel, and director reorientation in the electric discipline induced by light inside the LiNbO3:Fe substrates. might be consulted in Appendix https://brookswccdd.blogthisbiz.com/39063815/considerations-to-know-about-lithium-niobate-crystal