SiO2-HfO2 coated spherical microresonators

We present some results regarding the coating of spherical microresonators and their different applications in photonics. A thin film coating on the surface of the resonator can be used to modify significantly the optical properties of the resonator. We have coated the microresonators with a sol-gel derived 70SiO2-30HfO2 coating and have studied its effect on optical and spectroscopic properties of the microresonator. By coating the sphere with an optically active layer we managed to achieve lasing action in the sphere. We also studied the phase matching influence on the coupling between a tapered fiber and a microsphere. Furthermore we studied the effect of the modal dispersion in the sphere on the coating thickness and have managed to produce spheres with giant normal dispersion.