Interfacing whispering-gallery microresonators and free space light with cavity enhanced Rayleigh scattering

Jiangang Zhu, Şahin K. Özdemir, Huzeyfe Yilmaz, Bo Peng, Mark Dong, Matthew Tomes, Tal Carmon, Lan Yang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Whispering gallery mode resonators (WGMRs) take advantage of strong light confinement and long photon lifetime for applications in sensing, optomechanics, microlasers and quantum optics. However, their rotational symmetry and low radiation loss impede energy exchange between WGMs and the surrounding. As a result, free-space coupling of light into and from WGMRs is very challenging. In previous schemes, resonators are intentionally deformed to break circular symmetry to enable free-space coupling of carefully aligned focused light, which comes with bulky size and alignment issues that hinder the realization of compact WGMR applications. Here, we report a new class of nanocouplers based on cavity enhanced Rayleigh scattering from nano-scatterer(s) on resonator surface, and demonstrate whispering gallery microlaser by free-space optical pumping of an Ytterbium doped silica microtoroid via the scatterers. This new scheme will not only expand the range of applications enabled by WGMRs, but also provide a possible route to integrate them into solar powered green photonics.

Original languageEnglish
Article number6396
JournalScientific Reports
StatePublished - 2014
Externally publishedYes


FundersFunder number
National Science Foundation1231314
Army Research Office


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