Waveguide bend designs in three-dimensional woodpile photonic crystals

The transmission efficiency of electromagnetic waves through waveguide bends in a three-dimensional woodpile photonic crystal is investigated experimentally in the microwave regime. A stable technique of field extrapolation is employed to evaluate the coefficient of transmitted waves both for the reference straight waveguide and waveguide bend. We compare and analyze the transmission spectra of a wide variety of bend structures, and find that the multiface mirror scattering effect and cavity resonant effect in the bend zone are two major factors that influence the transmission property of the waveguide bends. A simple picture of the physical mechanism governing the electromagnetic wave transport at the bend zone can be drawn; this allows easier design of high-efficiency waveguide bend structures. (c) 2008 American Institute of Physics.