Affiliation:
1. Centre for Optical and Electromagnetic Research College of Optical Science and Engineering Zhejiang University Hangzhou 310058 P. R. China
2. Taizhou Hospital Zhejiang University Taizhou 318000 P. R. China
3. Shanghai Institute for Advanced Study, National Engineering Research Center for Optical Instruments Zhejiang University Hangzhou 310058 P. R. China
4. Department of Electromagnetic Engineering, School of Electrical Engineering KTH Royal Institute of Technology Stockholm, SE‐100 44 Stockholm Sweden
Abstract
AbstractTunable filters are vital not only for dynamic display but also in the miniaturized spectral imaging system. Yet, the present tunable devices possess low optical throughput, bulky volume, slow response, or complex configuration. In this paper, the study proposed and experimentally demonstrated a compact tunable filter module based on metagratings combined with liquid crystals (LC). By the synergetic effect between the birefringent LC and the dichroic metagratings, the module possesses distinct transmissive features by electrically tuning the LC material, resulting from the polarization interference effect. A simple nanoimprinting method, which is suitable for the mass production of nanostructures is adopted for low‐cost fabrication. These unique features endow the present tunable filter module with low cost, high optical throughput, and compact volume. As a proof of concept, a multispectral imager is built with this filter based on a commercial microscope. Experimental results show the system response is five times higher in optical throughput across the whole visible region than the traditional liquid crystal tunable filter and the signal‐to‐noise ratio can be improved by 7 dB. Considering the feasibility of nanoimprinting, this module paves the way for spectral imaging in low‐light conditions and on‐site scenarios such as tongue diagnosis and food quality inspection.
Funder
National Key Research and Development Program of China
National Natural Science Foundation of China
Subject
Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials