▎ 摘　　要

An infrared liquid-crystal microlens array (IR-LCMLA) is fabricated using an isothiocyanato nematic liquid crystal (NCSNLC) material sandwiched between graphene and aluminum electrodes without alignment layers; its focus is electrically tunable in a wide infrared region. The infrared microbeam diffraction crosstalk introduced by alignment layers in previous IR-LCMLAs with the same NCSNLC is eliminated. The graded-index lens effect is achieved using a spatially nonuniform electric field generated by a microhole array electrode and a high-birefringence NCSNLC thin film at wavelengths of similar to 0.9 to similar to 11 mu m. The IR-LCMLA is tuned by applying an external voltage signal; it acts as a phase retarder when the RMS voltage is below a threshold, and the tunable microlenses when the RMS voltage further increases. The proposed IR-LCMLA is an attractive candidate for infrared sensors utilizing arrayed microflux shaped and adjusted by the IR-LCMLA coupled or even integrated with them, infrared microbeam interconnection and switching, adaptive imaging based on wavefront measurement and correction, or other advanced adaptive optics applications. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement