Trapping light pulses at controlled perturbations in periodic optical structures

摘要

A gap soliton can be controlled by introducing a perturbation into a waveguide structure that includes an otherwise essentially periodic variation of its refractive index. In one embodiment of our invention, by controlling the amplitude, phase and/or average value of the refractive index of a first perturbation, and by maintaining the speed of the soliton below a certain critical speed, we have found that the soliton will transfer its energy to the modes of the perturbation. When the soliton transfers essentially all of its energy in this way, we refer to the soliton as being trapped or captured by the perturbation. Surprisingly, the soliton can be trapped without loss of a significant amount of its energy. In an alternative embodiment, when the speed of the soliton exceeds the critical speed, a second perturbation is introduced into the waveguide structure to reduce the speed of the soliton, thereby enabling its capture by the first perturbation. In another embodiment, a gap soliton is captured between two perturbation regions neither of which is capable of capturing the soliton by itself. Trapped gap solitons enable a variety of unique system applications in, for example, memories, buffers, switches and WDM demultiplexers.