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 drives 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 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.