http://bacterial-receptor.com/....index.php/parsonage-
For x-polarized incident light, the metadevice under forward illumination works as transmissive concentrating lens and vortex beam generator of y-polarized light, while under backward lighting it acts as a reflective vortex beam generator. On the other hand, for y-polarized event light, the metadevice under forward lighting acts as a reflective Bessel beam generator, while a mix of transmissive vortex beam generator and concentrating lens of x-polarized light under