Optical resonators have micrometer size dimensions and come mostly in two flavors, namely circular and racetrack
shaped microrings (MR), and microdisks (MD), although microsphere (MS) and photonic crystal microring (PCMR)
resonators are also expected to gain prominence. Highly advanced fabrication techniques in recent years resulted in the
reduction of propagation losses and in a remarkable increase of resonator Q factor and finesse. Newly developed
microresonators are therefore ideally suited for applications in highly selective communication filters, delay lines,
distributed and localized sensing, industrial measurements, microlaser mirrors and high-resolution spectroscopy. Since
the optical signal recirculates and spends a relatively long time trapped in a high Q cavity, microresonators enhance
light-light and light-particle interactions and are for this reason most promising to exploit nonlinear effects.
The talk will focus on advances in multiring photonic devices such as the coupled resonator optical waveguide (CROW)
and the side-coupled integrated space sequenced optical resonator (SCISSOR), on the link between photonic and
microwave filter design, on the effect of polarization on filter response and its control, on schemes and efficiency of
tuning and modulation and on MR composites used as reflectors and laser mirrors. The talk will also cover issues related
to design trends and technological advances, such as vertically stacked MRs, coiled optical resonators and resonators not
based on propagating waves, as well as techniques to extend the free spectral range (FSR) of periodic filters through the
Vernier principle and the use of polymer materials and two-dimensional photonic crystals to fabricate optical resonators.