POLARIZING REFLECTION GRATING BEAMSPLITTER FOR THE 10.6-MU-M WAVELENGTH

A polarizing grating beamsplitter working in reflection at the 10.6-mu m wavelength is presented. The grating was designed using rigorous dif fraction theory. The incident TM-polarized light is not diffracted but reflected as the zero order, and the TE-polarized light is mainly dif fracted into the +1 and -1 diffraction orders. The grating is a surfac e relief with a metal coating. It consists of V-grooves and is fabrica ted in silicon using photolithography and a combination of dry and wet chemical etching. The measured diffraction efficiencies agree with th e theoretical predictions. The sum of the measured diffraction efficie ncies of the +1 and the -1 orders is 90% for TE polarization and 6% fo r TM polarization. If the grating is in a conical mount, it can be use d as a beam attenuator or a three-way beamsplitter.