Microfiber Resonators in the Linear and the Nonlinear Regimes
Résumé
The microfiber resonators presented here were made by forming an open knot with silica microfibers in air. Resonance spectra were observed in the near infrared and more recently in the visible. The knot structure was mechanically stable and was maintained upon immersion in a liquid. Upon immersion the change of refractive index of the medium surrounding the knot shifted the spectral region where resonances were observed. Moreover, using a liquid which could be polymerized, we have imbedded microfiber knot resonators in a solid matrix to form rugged devices. In the presence of nonlinearity a resonator can exhibit bistability. This behaviour was studied both numerically and experimentally. In particular hysteresis cycles were measured in a silica microfiber knot and fitted to a model including the thermal response of the knot. The origin of the bistability observed so far is refractive, but it is also possible to obtain bistability using a saturable absorber. To this avail, we are now investigating the possibility of using carbon nanotubes as saturable absorbers interacting with the evanescent field of microfibers. Design issues and envisioned applications of microfiber bistable devices will be discussed.