Thermo-driven light controller by using thermal modulation of diffraction wavelength in holographic polymer dispersed liquid crystal grating

摘要

A microperiodic structure composed of polymer and liquid crystal (LC) phases, called holographic polymer dispersed liquid crystal (HPDLC), was fabricated based on a photo-induced phase separation technique by laser interferometric exposure. The diffraction wavelength of HPDLC gratings formed by different LC composites and grating structures was experimentally investigated by spectroscopic measurements as a function of temperature at around 30 ℃. The HPDLC gratings composed of nematic LC having low nematic to isotropic temperature (T_(NI)) and film thickness of 25 μm showed the switch of diffraction wavelength between visible and infrared lights by the change of temperature. The optical characteristics achieved in HPDLC gratings are expected to be applicable for the basis of diffractive type of thermo-driven light controller which can supply visibility constantly for solar-ray control windows.