Theoretical and experimental investigation of the second-order nonlinear optical properties of retinal and derivatives

We analyze the first hyperpolarizability β of the retinal chromophore and some of its derivatives. We investigate the influence of isomerization from trans to 13-cis conformation, as well as that of going from the retinal neutral form to the corresponding protonated Schiff base; the latter point is of particular interest because the protonated form is present in the bacteriorhodopsin protein.