Abstract
Generation of subwavelength beam sizes is a fascinating challenge with several implications. The observation of a 120 nm laser spot in the visible part of the spectrum is reported here. It has a size variation of less than 10% in a distance of $ 50\;\unicode{x00B5}{\rm m} $ along the axis of propagation. This so-called Arago spot results from the diffraction of the light from a laser diode by the edges of an absorbing disk. Applications are discussed and hollow beams carrying orbital angular momentum with a 400 nm diameter dark spot in the center are evidenced. This paves the way toward atom lithography via atom guiding or new spectroscopy on forbidden transitions.
© 2020 Optical Society of America
Full Article | PDF ArticleMore Like This
E. N. Bulgakov, K. N. Pichugin, and A. F. Sadreev
J. Opt. Soc. Am. B 37(11) 3335-3340 (2020)
Wenya Tian and Junhui Li
Appl. Opt. 59(29) 9225-9232 (2020)
Weronika Lamperska, Jan Masajada, Sławomir Drobczyński, and Piotr Wasylczyk
Appl. Opt. 59(15) 4703-4707 (2020)