Design of erbium doped microsphere lasers

The lasing characteristics of an erbium doped silica glass microsphere coupled to a tapered fiber are numerically investigated in the third band of the optical fiber communication. In the model, the electromagnetic field profile of the whispering gallery modes (WGMs) traveling in the microsphere is described by means of spherical Bessel functions for the radial dependence and spherical harmonics for the angular dependence, at both pump and signal wavelengths. Moreover, the microsphere laser operation has been simulated by taking into account the rare earth ion emission, via the rate equations, and the coupling with the tapered fiber. A number of simulations have been performed in order to demonstrate the feasibility of the active microspheres to be employed as distributed micro laser sources or to fabricate active microsensors