Slow light and enhanced light-matter interaction

Guided by experimental access to the photonic bandstructure,we investigated a structure that exhibited a seemingly stationary and localized light field; the upper bound of its speed was c/1000. We have steadily increased the useful bandwidth of the slow light. This has led to the world’s shortest 3λ directional coupler that was switched on a ps timescale.
By ultrafast, yet adiabatic, switching of its environment the frequency of propagating slow light was blue-shifted. We showed that the increased effective light-matter interaction of slow light inevitably limits its ultimate, useful slowdown to a value beyond which residual disorder leads to multiple scattering.
We have slowed down guided surface plasmon polaritons over a bandwidth as large as 4 THz. A slowdown of propagation through subwavelength hole arrays was achieved by tailoring the individual hole shape. This slowdown leads to the existence of a ‘hot hole’ shape for which second harmonics generation is boosted by almost two orders of magnitude.