Advances in Engineering Advances in Engineering features breaking research judged by Advances in Engineering advisory team to be of key importance in the Engineering field. Papers are selected from over 10,000 published each week from most peer reviewed journals.
Optics Letters, Vol. 38, Issue 17, pp. 3410-3413 (2013).
Annett B. Klemm, Daan Stellinga, Emiliano R. Martins, Liam Lewis, Guillaume Huyet, Liam O’Faolain, and Thomas F. Krauss.
Department of Physics, University of York, Heslington, York YO10 5DD, UK and
School of Physics & Astronomy, University of St Andrews, St Andrews KY16 9SS, UK and
Photonic Device Dynamics Group, Tyndall National Institute, Lee Maltings, Cork, Ireland
Abstract
We demonstrate high aperture (up to NA∼0.64) three-dimensional focusing in free space based on wavefront-engineered diffraction gratings. The grating lens’ optical response is tailored by spatially varying the grating ridge and groove width in two dimensions to achieve focal lengths of order 100 um that are crucial for micro-optical applications. The phase profile of the lens includes multiple 2π phase jumps and was obtained by applying an algorithm for finding the optimal path for both phase and amplitude. Experimental measurements reveal a lateral spot size of 5 um that is close to the size of a corresponding Airy disk.
© 2013 Optical Society of America
