Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators

Abstract

Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres can be thought as a store of energy with a huge variety of applications: compact laser sources, highly sensitive biochemical sensors and nonlinear phenomena. A protocol for the fabrication of both the microspheres and coupling system is given. The couplers described here are tapered fibers. Efficient generation of nonlinear phenomena related to third order optical non-linear susceptibility Χ((3)) interactions in triply resonant silica microspheres is presented in this paper. The interactions here reported are: Stimulated Raman Scattering (SRS), and four wave mixing processes comprising Stimulated Anti-stokes Raman Scattering (SARS). A proof of the cavity-enhanced phenomenon is given by the lack of correlation among the pump, signal and idler: a resonant mode has to exist in order to obtain the pair of signal and idler. In the case of hyperparametric oscillations (four wave mixing and stimulated anti-stokes Raman scattering), the modes must fulfill the energy and momentum conservation and, last but not least, have a good spatial overlap.

Coupling analysis of high Q resonators in add-drop configuration through cavity ringdown spectroscopy

“…The functions s tra and s drp (equations (9) and 10 . As a practical consequence, these symmetries lead to the possibility for different parameter sets to have identical transfer and drop profiles, leading to an ambiguous estimation of the parameters.…”

“…In particular, we realise an add-drop configuration by coupling the WGM resonator to two tapered fibers, therefore having a two coupler and a four port device. The add-drop configuration is very important for a number of studies based on ultra-high-Q WGM microresonators that have recently gained great interest, including, for instance, the implementation of innovative compact Kerr frequency combs [2][3][4][5], the generation of non linear parametric [6,7] and non-parametric [8,9] oscillations, the stabilization of semiconductor lasers operating in the resonators transparent wavelength range [10][11][12], or the modelocking of fast pulsed lasers [13]. In these experiments, where the frequency conversion through non-linear effects (as well as laser oscillations [14]) is accomplished within the resonators, the add-drop configuration allows us to efficiently collect the signal through the drop channel, while keeping the residual pump on the transfer channel.…”