Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE
Optical measurement of the phase shift introduced by a slow-light medium based on coupled erbium-doped fiber resonators
Yannick Dumeige, Thị Kim Ngân Nguyên, Laura Ghişa, Stéphane Trebaol, Patrice Féron
Abstract
Since the proposition of D.D. Smith et al. [Phys. Rev. A 69 pp. 063804, 2004], the experimental demonstration of coupled resonator induced transparency has been made using passive fiber or whispering-gallery-mode microspheres. These demonstrations show that it is possible to integrate delay lines using high quality resonators. The maximal group delay that it can be introduced depends mainly on the relative value of the intrinsic losses with respect to the value of the coupling between the resonators. In this paper we experimentally show that the limit given by the intrinsic losses of the resonators can be circumvented by using active resonators. Our experimental setup consists in two coupled Er3+ doped fiber resonators. Each resonator can be pumped independently. Consequently, the values of the residual losses in the two resonators can also be modified independently. We then show that the transparency of the coupled resonators can be maximized using the right pumping rate in each resonator. By inserting this device into one arm of a fiber Mach-Zehnder interferometer we are able to optically measure the phase shift produced by the coupled resonators as a function of the optical frequency. The group delay can be deduced from this information.