Giant gain enhancement in surface-confined resonant Stimulated Brillouin Scattering

Nathan Dostart, Seunghwi Kim, Gaurav Bahl

Research output: Contribution to journalArticlepeer-review


The notion that Stimulated Brillouin Scattering (SBS) is primarily defined by bulk material properties has been overturned by recent work on nanoscale waveguides. It is now understood that boundary forces of radiation pressure and electrostriction appearing in such highly confined waveguides can make a significant contribution to the Brillouin gain. Here, this concept is extended to show that gain enhancement does not require nanoscale or subwavelength features, but generally appears where optical and acoustic fields are simultaneously confined near a free surface or material interface. This situation routinely occurs in whispering gallery resonators (WGRs), making gain enhancements much more accessible than previously thought. To illustrate this concept, the first full-vectorial analytic model for SBS in WGRs is developed, including optical boundary forces, and the SBS gain in common silica WGR geometries is computationally evaluated. These results predict that gains 104 times greater than the predictions of scalar theory may appear in WGRs even in the 100 μm size range. Further, trapezoidal cross-section microdisks can exhibit very large SBS gains approaching 102 m-1W-1. With resonant amplification included, extreme gains on the order of 1012 m-1W-1 may be realized, which is 108 times greater than the highest predicted gains in linear waveguide systems.

Original languageEnglish (US)
Pages (from-to)689-705
Number of pages17
JournalLaser and Photonics Reviews
Issue number6
StatePublished - Nov 1 2015


  • Brillouin gain
  • Nonlinear optics
  • Optical forces
  • Radiation pressure
  • Stimulated Brillouin Scattering
  • Whispering gallery resonators

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics


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