Slow light in photonic crystals with loss or gain

Abstract

We develop a perturbation theory for slow-light photonic-crystal waveguides engineered to suppress groupvelocity dispersion, and predict that weak material loss (gain) is enhanced proportionally to the slow-down factor, whereas the attenuation (amplification) rate saturates for loss (gain) exceeding a certain threshold. This happens due to hybridization of propagating and evanescent modes which allows significant intensity enhancement observed in our numerical simulations for photonic crystal waveguides even under strong material losses.