Comments about dispersion of light waves

Dispersion of light waves is well known, but the subject deserves some comments. Certain classical equations do not fully respect causality; as an example, group velocity v g usually given first derivative angular frequency ? with to spatial k m (or wavenumber) in medium, whereas it that depends on . This paper also emphasizes use phase index n and , inverse their respective velocities, normalized 1/ c free-space velocity. clarifies understanding dispersion equations: parameter D related wavelength ? whilst GVD now One notices term second order does have same meaning or In addition, two original amusing geometrical constructions are proposed; they simply derive from a tangent which helps visualize relationship. applies bulk materials, optical fibers waveguides, this can be extended birefringence polarization mode polarization-maintaining birefringent waveguides.