Soliton frequency shifts in subwavelength structures

Abstract

We investigate the soliton frequency shifts for few-cycle ultrashort laser pulses propagating through resonant media embedded within subwavelength structures, and we elucidate the underlying physics. Full-wave Maxwell-Bloch equations are solved numerically by using the finite-difference time-domain method. It is shown that both soliton blueshift and redshift can occur by changing the period of the structures. We found that the rereflected waves play an essential role in this process. When the pulse propagates through the periodic structures, the reflected waves can be rereflected back by the thin layers, which can further induce the controllable frequency shifts of the generated solitons. This suggests a way to tailor the light solitons over a large spectral range.