Quality factor of ring electromagnetic oscillation modes in the dielectric sphere with allowance for optical inhomogeneity on its surface

Special features of electromagnetic energy distribution in a dielectric sphere with optical inhomogeneities on the surface

“…In terms of geometric optics, this means that a ray of light incident close to the tangent to the rough surface is reflected as from a mirror, whereas from the standpoint of wave optics, this implies that the incident electromagnetic wave exhibits tunneling through the surface protrusions [5]. This phenomenon accounts for the high Q of WGMs in the dielectric sphere with surface inhomogeneities [5] and allows this rough surface to be considered as perfectly smooth for the WGMs.…”

“…In the case of a resonator possessing ideal spherical symmetry, the WGMs are degenerate even in the pres ence of the aforementioned roughnesses [4,5]. Since we are dealing with roughnesses that represent an ensemble of protrusions with various, randomly dis tributed shapes and dimensions (not exceeding the light wavelength), the angles of refraction on these inhomogeneities are also randomly distributed.…”

“…This cou pling leads to energy exchange between modes [2]. According to an important result that has been obtained recently [5], surface roughnesses with heights and lateral sizes of protrusions smaller than or equal to the light wavelength do not decrease the figure of merit (Q value) of ring modes close to the spherical surface (i.e., WGM modes). In terms of geometric optics, this means that a ray of light incident close to the tangent to the rough surface is reflected as from a mirror, whereas from the standpoint of wave optics, this implies that the incident electromagnetic wave exhibits tunneling through the surface protrusions [5].…”