Focusing Efficiency

Focusing efficiency is the power within the focal area divided by the power incident on the lens. For MOI lenses, incident power is the power incident on the unit cell layer. For SOI lenses, it's the power incident on the substrate.

SMD PRO provides two options of focal area: circle and square (see image below). This allows users to obtain the focusing efficiency of their lens with the appropriate evaluation geometry. For example, if the metalens was used with a square aperture and the shape of the beam after passing through the lens was also square, then it may be more reasonable to use square focal area.

• Focal area:

  • Circle: a circle on the focal plane with a diameter equal to 6 X FWHM [ref.].

  • Square: a square on the focal plane with a side length equal to 6 X FWHM.