Abstract

Since its introduction a few years ago, the idea of photonic bands in 3-D periodic dielectric structures has been rapidly gaining acceptance. Initial theoretical calculations of photonic bands based on the scalar wave equation have quickly been replaced by full vector wave calculations based on Maxwell’s equations. Realistic computations can now be made using the plane-wave method. A structure exhibiting a bonafide forbidden frequency gap has recently been proposed by Yablonovitch. Results computed for the bands and the attenuation length within the band gap are in excellent agreement with experimental findings. The gap size to mid-gap ratio is found to be ~19%. The gap persists for refractive-index contrast as low as 2. In a similar structure more appropriate for microfabrication, the relative gap size can be as large as 21%. The minimum threshold refractive-index contrast for a true gap, however, remains ~2.

© 1991 Optical Society of America