COMPACT AND ULTRA-LOW-LOSS PLANAR PHOTONIC CRYSTAL TAPER

We propose a novel method to enhance the coupling efficiency between a dielectric waveguide and a planar photonic crystal (PC). The proposed method is based on introducing structural imperfections to change the mode size and shape inside the taper to match that of the PC line-defect waveguide. This method involves changing both the size and position of the inner taper rods. We found that the transmission efficiency is above 88% for the size change method. while it is above 94% far the position change method. The order of which method to apply first is important. Our results show that applying the size change method, followed by the position change method increases the coupling to about 96% without affecting the transmission spectrum of the structure. We also found that the input and output taper geometries are different because light faces different scattering mechanisms when entering or exiting the line defect waveguide. (2009 Wiley Periodicals. Inc). (C) 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1454-1459, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DO! 10.1002/mop.25222