A Proposal for Loss Engineering in Slow-Light Photonic Crystal Waveguides

The authors present a loss engineering method for slow-light photonic crystal (PhC) waveguides. Our proposed method for engineering the loss is based on optofluidic techniques to produce low propagation loss in the low dispersions slow-light regime. We numerically demonstrate that this approach allows one to control the propagation loss (from 180 to 120 dB/cm) by selective infiltration of suitable fluids into air holes of a PhC waveguide around the group velocity of c/55 to c/70. It is proposed that fabrication imperfections, i.e., roughness and other deviations from an ideal structure that lead to propagation losses, can be compensated by a selective nanoinfiltration method. A loss of 150 dB/cm for loss-engineered waveguides, compared to 230 dB/cm for conventional waveguides, is numerically demonstrated, while both waveguide structures maintain the same group index-bandwidth product.