Observation of Poynting’s vector reversal in an active photonic cavity
Ali K. Jahromi, Ayman F. Abouraddy · Optica · 2016
Optical power flow along an active cavity having net gain can differ dramatically from that in a passive cavity. We report the first observation of Poynting’s vector reversal in an active cavity under scattering boundary conditions. At a sub-lasing gain,which we call Poynting’s threshold,a null develops in Poynting’s vector,which divides the cavity into sections with oppositely directed energy flows. Furthermore,we demonstrate that the direction of Poynting’s vector at a fixed point in an active cavity can be controllably reversed without changing its magnitude via an intra-cavity passive element,thereby suggesting a potential methodology for optical switching.