Brillouin interaction in optical waveguides and microcavities

Abstract

Brillouin scattering occurs due to the interaction of optical and mechanical waves and it leads to the inelastic scattering of pump photons to Doppler red-shifted (Stokes) or blue-shifted (anti-Stokes) photons. The Brillouin scattering process is characterized by short-wavelength mechanical modes that can scatter light with a frequency shift of tens of GHz. In optical waveguides and microcavities this interaction occurs due to a combination of the photo-elastic effect, induced by strain, and moving-boundary effect caused by the mechanical mode distortion of the optical boundaries. These two scattering processes are strongly influenced by optical and mechanical properties of the confining structure and can be tailored for various applications; for instance, the generation of anti-Stokes photons, which is accompanied by destruction of phonon quanta, can be used to cool down mechanical modes in optical cavities; whereas the generation of stokes photons, which create phonons (heating), may foster the development of high-coherence lasers, ultra-stable radio frequency (RF) synthesizers, and broadband tuning of RF filters. This master dissertation will focus on investigating Brillouin scattering within optical microcavities. The final goal is to demonstrate and control Brillouin lasing within optical microcavities. (AU)