A computational model for the whispering gallery modes inside a microsphere resonator is presented. In the archetypical microsphere resonator sensor, a tunable laser light beam is injected into an optical fiber and coupled with the resonator’s cavity. The resonant optical coupling is achieved by bringing the fiber in the vicinity of the cavity’s evanescent field. The transmission spectrum is then observed to detect the WGM shifts. In this paper, two-dimensional models of a single laser source put near the equator of a microsphere are simulated using COMSOL Multi-physics 5.1 electromagnetic waves, beam envelopes library. Afterwards, a three-dimensional model of two laser sources put near the horizontal and vertical equators of a microsphere is computed. The transmission spectrum of both simulations was taken and cross correlation was performed on them. Results show a big similarity between both simulations and could bring a breakthrough in the area of optical sensors.