3D laser nano-printing on fibre paves the way for super-focusing of multimode laser radiation
MetadataShow full item record
Multimode high-power laser diodes suffer from inefficient beam focusing, leading to a focal spot 10-100 times greater than the diffraction limit. This inevitably restricts their wider use in 'direct-diode' applications in materials processing and biomedical photonics. We report here a 'super-focusing' characteristic for laser diodes, where the exploitation of self-interference of modes enables a significant reduction of the focal spot size. This is achieved by employing a conical microlens fabricated on the tip of a multimode optical fibre using 3D laser nano-printing (also known as multi-photon lithography). When refracted by the conical surface, the modes of the fibre-coupled laser beam self-interfere and form an elongated narrow focus, usually referred to as a 'needle' beam. The multiphoton lithography technique allows the realisation of almost any optical element on a fibre tip, thus providing the most suitable interface for free-space applications of multimode fibre-delivered laser beams. In addition, we demonstrate the optical trapping of microscopic objects with a super-focused multimode laser diode beam thus rising new opportunities within the applications sector where lab-on-chip configurations can be exploited. Most importantly, the demonstrated super-focusing approach opens up new avenues for the 'direct-diode' applications in material processing and 3D printing, where both high power and tight focusing is required.
Sokolovskii , G S , Melissinaki , V , Fedorova , K A , Dudelev , V , Losev , S N , Bougrov , V E , Sibbett , W , Farsari , M & Rafailov , E U 2018 , ' 3D laser nano-printing on fibre paves the way for super-focusing of multimode laser radiation ' , Scientific Reports , vol. 8 , 14618 . https://doi.org/10.1038/s41598-018-32970-6
Copyright © The Author(s) 2018. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
DescriptionEUR was partially supported by Grant of Russian Ministry of Science and Education (Grant No. 18-15-00172).
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.