A cylindrically symmetric negative-index grating lens composed of unitary material is proposed as an effective method to modulate the focusing of cylindrical vector beams (CVBs).
The grating parameters are designed to obtain an appropriate negative index, and the lens profile is tailored to realize the constructive interference.
The plano-concave lens is parameterized to achieve desired focal length.
The plano-cone lens is proposed to obtain large depth of focus.
The presented modulation methods can be applied for any arbitrary polarized CVBs.