Electroinduced and photoinduced effects in optical second-harmonic generation and hyper-Rayleigh scattering from thin films of bacteriorhodopsin

The mechanism of optical second-harmonic generation (SHG) in thin solid oriented and nonoriented films of bacteriorhodopsin (bR) is studied. The role of the random spatial inhomogeneity of the quadratic susceptibility in the mechanism of diffuse and depolarized SHG in thin solid bR films is discussed. A hyper-Rayleigh scattering formalism is used for the description of SHG in these films. Electroinduced and photoinduced effects in SHG are detected, and the saturated concentrations of the electroinduced and the photoinduced spectral forms of this type of bR film are estimated. Nondestructive SHG readout of bR-based optical memories is suggested. (C) 1997 Optical Society of America.