How could we use this techniques for studying Membrane protein ?

This depends on the protein you want to control. There is a number of optogenetic tools which enable control of membrane channels or receptors via conformational switch, homo- or heterodi(oligo)merization or recruitment of interaction partners. Selection of the optimal tool depends on 1) the activation mechanism of the protein you want to control, 2) cell type or tissue of interest and experimental setup (for example, some cell types have low tolerance of violet or blue light, and performing experiments in thicker samples might benefit from using red or far-red light-activated receptors), and 3) availability of endogenous cofactors for your photoreceptor in your model organism.