We present here a highly-miniaturized continuously tunable optical bandpass filter in the MIR range for chemical detection in microreactors. Similar to a Fabry-Perot interferometer, the micro filter consists of two parallel multi-thin-film Bragg mirrors and an air gap, spaced by Liquid Crystal Elastomers (LCEs). The LCE is a novel actuator material composed of crosslinked polymer chains exhibiting strong macroscopic contraction as temperature is raised. We will show that the LCE can provide an extremely precise yet large mechanical movement of the two parallel mirrors leading to large freedom in the wavelength tuning range. Design, fabrication and measurements will be shown, demonstrating the functionality of the filter.
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Ziyu Wang, Yannick Folwill, Phuong-Ha Cu-Nguyen, Hans Zappe, "Tunable bandpass filter for mid-infrared wavelengths using liquid crystal elastomer actuators," Proc. SPIE 10545, MOEMS and Miniaturized Systems XVII, 105450D (22 February 2018);