High-Q Factor Optical Whispering-Gallery Mode Microresonators and Their Use in Precision Measurements

Fluorescent and lasing whispering gallery mode microresonators for sensing applications

“…Due to their extremely high Quality factor (Q‐factor), defined as the ability to store energy, and their small mode volume , WGM resonators have found applications spanning sensing through to quantum electrodynamics (QED) and non‐linear optics . The applications come with an equal diversity of geometries including spheres , hemispheres , capillaries , bubbles , bottles , fibers , knots , toroids , rings and disks .…”

“…For either technique, this allows efficient coupling to the WGMs. Passive resonators have shown tremendous performance, especially in terms of the Q‐factor which in some cases can exceed 10 11 , but also in terms of ultra‐small mode volumes which is important for QED and non‐linear applications. Note however that the requirement for external evanescent coupling configurations, may render any real‐life applications outside laboratory environments problematic.…”

Method of producing tapered optical fiber

“…Maintaining effective coupling is an important task during the operation of such devices. The monograph [8] describes various methods of coupling with the use of optical fibers (OFs) and prisms and coupling via separate scattering centers and surface inhomogeneities. Most effective methods of coupling are based on the effect of frustration of total internal reflection, where coupling is performed via an evanescent field.…”