Dual-wavelength polarization-tunable holographic response in an azobenzene-containing film

We report a polarization-tunable holographic system in an azobenzene-containing liquid crystal film enabled by dual-wavelength excitation. The 405-nm beam facilitates the accumulation of cis-isomers and enhances molecular mobility, while the 532-nm beams induce photoisomerization and polarization-selective molecular alignment. Their cooperative action yields a nonlinear holographic response, resulting in a twofold increase in diffraction efficiency compared to single-wavelength excitation. By tuning the polarization states of the 532-nm beams, a continuous transition from an amplitude to polarization grating is realized, together with passive all-optical switching. This approach offers a versatile strategy for dynamic holographic modulation, with potential applications in tunable photonic elements, polarization-selective optical devices, and reconfigurable optical switches driven by polarization control.