Study on nanoimprinting technique for subwavelength micro-polarizer array with high uniformity

This paper presents the fabrication of a high-uniform division of focal plane (DoFP) micro-polarizer array (MPA) based on nanoimprint lithography (NIL) technology. Comprehensive analysis has been conducted on the impacts of spin coating conditions, contact speed, imprinting pressure, and separate speed on the pattern fidelity. The issue of excessive defects caused by sharp changes of pattern density at the edge has also been addressed. Hereby the optimal process parameters at the current stage were attained. Within an area of 16mm×12.8mm, a 640×512 pixelated medium wave (MW) wire grating array was implemented, which involved four different orientations of 0°, 45°, 90°, and 135°, as well as line width down to 200nm. For wire gratings located in both the edge and central regions, the width variations can be controlled around 10nm. After etching, the width variation of wire grating can still be preserved around 10nm. Integrating the MPA with the IR focal plane detector array, an effective pixel rate over 99.9% has been demonstrated.