MWIR Meanderline Reflective Quarter-Wave Plate

We present, for the first time, a design and measured data for a meanderline reflective quarter-wave plate suitable for operation in the 3- to 5-micron MWIR band. Across this spectral range, the reflection coefficient is around 80%, the axial ratio is less than 2, and the polarization conversion ratio is above 75%. We also demonstrate experimentally that the meanderline structure has stable performance as a reflective quarter-wave plate over a 20-degree angular bandwidth centered around incident angles between 35 and 55 degrees. One notable difference as compared to LWIR meanderline waveplates is that the vertical height of the grid lines is necessarily larger, to keep the relative phase between TE and TM near 90°.