Snigdha Thekke Thalakkal

In this letter, we present an experimental and theoretical study of the radiation pressure-induced periodic and quasi-periodic routes to chaos in silica microspheres. We demonstrate that the Kerr effect is essential for correct interpretation of the experimental results both quantitatively and qualitatively and propose a new system of equations to describe opto-mechanical phenomena. Quantitatively, we observe chaotic behaviour for very small values of threshold pump power. Qualitatively, we report a novel double torus behaviour that is not possible in the absence of Kerr effect.

We reported lasing in Er3+ doped tellurite glass whispering gallery mode microspheres fabricated using the plasma torch method.15Na2O25WO360TeO2 doped with 0.5 mol% Er3+ is used for the fabrication of microspheres. Laser light from the pump is coupled to the microsphere through a half and a full tapered fiber. An optical spectrum analyzer receives the counter propagating light from the microsphere. Pump lasers of 980 nm and 1480 nm are used to achieve the laser emission at 1570 nm.

We present a theoretical analysis of the refractometric sensitivity of a spherical microresonator coated with a porous sensing layer performed for different whispering gallery modes. The effective refractive index of the modes is also calculated. The calculations are also made for a system which has an additional high-refractive index layer sandwiched between the microsphere and the porous sensing layer. The results of the calculation are discussed in regards to the applicability of the studied systems for gas sensor construction.