Enhanced transmission through photonic-crystal-based bent waveguides by bend engineering

We have studied the transmission of light through two-dimensional photonic- crystal-based waveguides with two 60 degrees bends. The waveguides consist of three or five missing rows of holes inside a triangular photonic crystal block fabricated on an AlGaAs/GaAs waveguide structure. Fine tuning of the bend design results in a severe impact on the transmission behavior, leadi ng to losses as low as 1.1 dB/bend. Measurements of losses in the bends wer e performed by a comparison with a straight guide of identical length. (C) 2001 American Institute of Physics.