A characterization bench to analyse various types of optical WGM resonators for high spectral purity microwave sources applications

Abstract

We have set up a characterization bench to test the optical and microwave properties of high Q optical whispering gallery mode resonators. The bench comprises nanometer scale precision 3D displacement stages mounted on an anti-vibration table in order to get a very fine coupling between the optical resonator and the tapered fibers used for coupling. This bench can be adapted to different types of resonators: mum- and mm-spheres of SiO2 or monocrystalline disks. In this paper we present several approaches which have been investigated in order to test these resonators. Different types of optical sources have been used: a broadband 'white light' source around 1550 nm, a T-control free-running laser emitting at ~1550 nm, an external cavity laser with a narrow spectral width. We have also performed a temperature control of the sphere. Finally, we are trying to lock the laser on a sphere optical mode in order to get a stable system