Engineering the dispersion of a fibre mode via molecular coherence

Abstract

Propagation of a fibre mode inside a thin optical fibre surrounded by a molecular solid of ortho-H₂ doped in a matrix of para-H₂ crystal is considered. The evanescent fields of the fibre modes interact with the molecular solid which behaves as an electromagnetically induced transparency medium. It is shown that the dispersion behaviour and hence the group velocity of a weak (probe) field fibre mode can be manipulated by coherently controlling the dispersion of the surrounding medium via another strong (control) evanescent field of the thin fibre, using a low density crystal surrounding the fibre. For a set of experimental parameters of the medium, fibre and fields, the group velocity of the fibre mode could be drastically reduced to about a few hundreds of ms^−1.