Dynamic resonant waveguide crossed gratings for wavelength-selective polarization conversion and optical modulation

Two-dimensional Resonant Waveguide Crossed Gratings (RWCG) were fabricated on azobenzene molecular glass thin films and their resonance behavior was studied once placed in between orthogonally aligned polarizers. Normally-incident polychromatic light was transmitted and/or reflected from these RWCGs only in narrow positive peaks. In addition, the central wavelength and transmitted intensity of these positive peaks were actively modulated by an external light source. Furthermore, a dynamic volume birefringence behavior related to the photomechanical effect of the azobenzene chromophores was observed. A mechanism to explain the polarization conversion of the resonant light using RWCGs at normal incidence was also proposed.