Half-integer optical angular momentum and mode orientation control in photonic crystal microrings

In a recent article in Physical Review Letters, we demonstrate how control of a photonic crystal patterning applied to a microring resonator can lead to novel states of light.

 

In this case, we demonstrate whispering gallery modes exhibiting half-integer optical angular momentum. While in a convetional microring resonator, after one round trip the light field returns to its original phase (modulo 2*pi), for modes with half-integer optical angular momentum, it takes two round trips. This is analogous to the well-known Mobius strip.

 

We further show that defects incorporated into the photonic crystal patterning both enable highly localized optical modes as well as orientation control of more distributed optical modes.  Together with our previous work on high quality factor slow light and its strong localization in photonic crystal microrings, these results illustrate how photonic crystals and microrings can be combined together to realize wide-ranging control of optical modes in integrated photonics.

 

Our work has been recognized as a PRL Editors' Suggestion, featured in Physics and Physics Today, and highlighted in Nature and phys.org.