Wide range group delay tuning in lossy fiber ring resonators

Abstract

We demonstrate theoretically and experimentally that a wide-range tuning of group delay values can be achieved in a lossy fiber ring resonator. The tuning mechanism relies simply on varying the loss/coupling ratio in the resonator. This simple structure may be used advantageously in different regimes for many sensing configurations, both for achieving extremely high sensitivity enhancements (by working close to critical coupling, where the group index becomes extremely large) or suppression of undesired refractive index effects (e.g. Kerr effect), by working in the under-coupled regime.