Acoustic build-up in on-chip stimulated Brillouin scattering.
We investigate the role of the spatial evolution of the acoustic field in stimulated Brillouin scattering processes in short high-gain structures. When the gain is strong enough that the gain length becomes comparable to the acoustic wave decay length of order 100 microns, standard approximations treating the acoustic field as a local response no longer apply. Treating the acoustic evolution more accurately, we find that the backward SBS gain of sub-millimetre long waveguides is significantly reduced from the value obtained by the conventional treatment because the acoustic mode requires several decay lengths to build up to its nominal value. In addition, the corresponding resonance line is broadened with the development of side bands. In contrast, we argue that intra-mode forward SBS is not expected to show these effects. Our results have implications for several recent proposals and experiments on high-gain stimulated Brillouin scattering in short semiconductor waveguides.
Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS).|School of Mathematical and Physical Sciences, University of Technology Sydney, NSW 2007, Australia.
C
C
Wolff
Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS).|MQ Photonics Research Centre, Department of Physics and Astronomy, Macquarie University, NSW 2109, Australia.
M J
MJ
Steel
Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS).|Institute of Photonics and Optical Science (IPOS), School of Physics, University of Sydney, NSW 2006, Australia.
B J
BJ
Eggleton
Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS).|School of Mathematical and Physical Sciences, University of Technology Sydney, NSW 2007, Australia.
C G
CG
Poulton