Micromachined sub-millimeter and millimeter wave variable polarisation compensator

A micromachined variable polarisation compensator has been designed and demonstrated experimentally at 100 GHz. The device uses two interlocking artificial dielectric gratings to produce a birefringence that varies as a function of the separation distance. The maximum phase difference was measured to be 74/spl deg/, in good agreement with computer simulations. Quarter wave dielectric antireflection coatings can be added to the exterior surfaces to reduce the insertion loss.