Active control of light extraction in the near-IR range with sub-wavelength periodic structures

Due to their narrow reflection peak as well as their compact structure, Guided Mode Resonance Filters (GMRFs) are attractive for many applications. We demonstrate the possibility to modulate the properties of a GMRF by associating with liquid crystals (LCs). By impregnating the diffraction grating with LCs, it is possible to switch between an active and an inactive state depending on the polarization of the light or the applied voltage. In this paper we fabricated and characterized the first diffraction order of LC-impregnated gratings with different periods (0,8 to 5,0μm) and depths (130 to 840nm) to test the ability of liquid crystals to adjust the diffraction properties. Finally, 99.8% of diffraction turn off with a 90° rotation polarization at zero voltage and 90 to 99% by applying a voltage of 30 V according to the grating dimensions. The effect of the grating dimension on the diffraction modulation capacity will be discussed.