The counter-propagation of two orthogonally polarized lasers generates a standing wave in polarization with a gradient between σ σ − − (left-hand circularly polarized light), linear, and σ σ + (right-hand circularly polarized light) along the standing wave. Note that this counter propagation does not make a standing wave in intensity, but only in polarization. This gradient occurs over a length scale of λ λ 2 , and then repeats, mirrored about the y-z plane. At positions where the counter-propagating beams have a phase difference of π π 2 , the polarization is circular, and where there is no phase difference, the polarization is linear. In the intermediate regions, there is a gradient ellipticity of the superposed fields.