Nonlinear optical properties of a bacteriorhodopsin film in a Fabry–Perot cavity

Bacteriorhodopsin is a photosensitive molecule found in the purple membrane of Halobacterium halobium. To investigate the possibility of using photoinduced changes in its refractive index in the 650-800-nm region for photonic switching, we prepared solid dry bacteriorhodopsin films with low scattering and examined their optical properties in a Fabry-Perot cavity. Interference fringes, generated on irradiation of the cavity with a near-IR laser beam at 792 nm, were shifted by simultaneous exposure to a 5-mW/mm(2) beam at 543.5 nm. This result indicates that such a Fabry-Perot cavity may be used as a photonically controlled spatial light modulator.