Artificial Dielectric Devices for Variable Polarization Compensation at Millimeter and Submillimeter Wavelengths

Variable polarization compensation has been demonstrated at 100 GHz. The device consists of two interlocking V-groove artificial dielectric gratings that produce a birefringence that varies with the separation distance. A maximum retardance of 74 has been obtained experimentally in a silicon device, in good agreement with rigorous coupled-wave computer simulations. Further simulations predict that adding quarter wave dielectric antireflection (AR) coatings to the outer surfaces of the device can reduce the insertion loss to below 4 dB. The use of rectangular grooved gratings provides increased retardance and reduced loss. It is predicted that a coupled device with a rectangular grooved gratings will be capable of maximum retardance in excess of 180 , with low insertion loss ( 0.6 dB). The sensitivity of the wave retardation as a function of mechanical separation has a peak value of 485 /mm. The design and micromachining fabrication techniques scale for operation at submillimeter wavelengths.