IMPROVED POLARIZER IN THE INFRARED - 2 WIRE-GRID POLARIZERS IN TANDEM

A widely used polarizer in the IR is the wire-grid polarizer. Wire-gri d polarizers with a typical minimal wire spacing of similar to 0.25 mu m perform well in the middle IR and the far IR, but in the near IR th e performance deteriorates as the wavelength approaches the wire spaci ng. A possibility for improving this performance is to put two wire gr ids in tandem with their transmission axes parallel. Starting with the extended Mueller matrix description for a single wire grid, we presen t a mathematical treatment of this tandem polarizer showing that perfo rmance improves quadratically; e.g., a single polarizer extinction rat io of 100 increases to a tandem extinction of 10,000. The improved per formance is also verified experimentally.