We report the focusing of light to generate a subdiffractive, subwavelength focal spot of full width half maximum 222 nm at an operating wavelength of 633 nm using an optical eigenmode approach. Crucially, the spot is created in the focal plane of a microscope objective thus yielding a practical working distance for applications. The optical eigenmode approach is implemented using an optimal superposition of Bessel beams on a spatial light modulator. The effects of partial coherence are also discussed. This far field method is a key advance toward the generation of subdiffractive optical features for imaging and lithographic purposes.
Bibliographical noteFunding Information:
We thank the UK Engineering and Physical Sciences Research Council for funding (grant EP/F040644/1) and Mark Dennis for helpful discussions. K.D. is a Royal Society Wolfson Merit Award Holder.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)