Response to: Comment on 'What is negative refraction?'

Martin W. McCall, Paul Kinsler, Alberto Favaro


    Photonics,
    Blackett Laboratory, 
    Imperial College London, 
    London SW7 2AZ, 
    United Kingdom

    J.Mod.Opt. 57, 2103 (2010)

    doi:10.1080/09500340.2010.503012

Much of the confusion in the preceding Comment is resolved once the correct
origin and definition of the phrase Negative Phase Velocity (NPV) propagation
is recognised. Markel's claim that Im(k_1^2)<0 is a predictor for negative
refraction is incompatible with taking ExB/mu_0 as the absolute measure of the
electromagnetic flux, and gives distinct results to P · Re(k) < 0 for
anisotropic media. We argue that  P=(1/2)Re(ExH^*) is the appropriate
electromagnetic flux vector for defining negative refraction since its normal
component is conserved across an interface. We also show how an induced
magnetisation affects both the work done by the electromagnetic field on bound
currents and the resultant electromagnetic flux.  

Keywords:  negative refraction; negative phase velocity; Poynting vector