Transmittance of a tunable filter at terahertz frequencies

A metallic photonic crystal filter has been demonstrated at terahertz frequencies, with the passband tunable over the range of 365-386 GHz. Tuning is achieved by a relative lateral shift of two metallic photonic crystal plates. Each plate is comprised of two orthogonal layers of gratings and integral mounting lugs. The plates are micromachined from silicon wafers then coated in gold to provide metallic electromagnetic behavior. An insertion loss of 3-7 dB and Q in the range of 20-30 was achieved. A shift of 140 mum gave a tuning range of 21 GHz, tuning sensitivity of 150 GHz/mm, and a fractional tuning range of 6%. (C) 2004 American Institute of Physics.