Optical microresonators

Optical microcavities are structures where the light is confined into a small volume. In particular, micro-disks, micro-rings, micro-toroids and microspheres use a total internal reflection mechanism produces the so called whispering gallery mode (WGM) resonances.


On fluorescent optical micro-cavities, the luminescent spectrum of the active material is modulated by the WGM spectrum, which enhance the spontaneous emission rate at the resonant frequencies due to the Purcell effect. One of the most direct applications of these structures is in chemical or bio-sensing, refractive index and temperature sensing, but relevant findings have also been achieved towards using them as all-optical switches and opto-mechanical oscillators. Among all micro-resonators, the microspheres have some key features, they can be made from many compositions including polymers, crystalline or glassy phases and they can have ultra-high quality factors (Q) up to 1010, which means a very high storage time of the light into the resonant cavity.


Left: Microsphere over a glass tip. Right: Microspheres over silicon nitride waveguides

The recent work on microspheres by the group at La Laguna University lead to a number of papers in high impact factor journals that can be seen in the Published papers section.

Some the papers about optical microresonators are:

Laser emission in Nd3+ doped barium-titanium-silicate microspheres under continuous and chopped wave pumping in a non-coupled pumping scheme.

Local characterization of rare-earth-doped single microspheres by combined microtransmission and microphotoluminescence techniques.

Whispering gallery modes in glass microspheres: optimization of pumping in a modified confocal microscope.

Whispering gallery modes in a glass microsphere as a function of temperature.