Grating axicon for collimating Čerenkov radiation waves

Abstract

An axicon optical element that utilizes a diffraction grating has been fabricated for collimating the Cerenkov radiation wave. The grating axicon has the advantage of a simple structure, which can easily be fabricated by the computerized numerical control machining technique. The collimation function of the grating axicon is confirmed for Cerenkov-type second-harmonic generation in LiNbO(3) waveguides, and correction of the aberration caused by substrate anisotropy is investigated. The aberration can be compensated by appropriately inclining either the substrate facet or the grating axicon.