Generating an optical needle with prescribed length and polarization direction through reversing the radiation pattern from a spatial ULS antenna

Abstract

Unlike the conventional optical needle directed along the optical axis, we propose an approach to generate an optical needle with prescribed polarization direction and length by inversely focusing the radiation pattern from a spatial uniform line source (ULS) antenna in a 4Pi focusing system. The spatial ULS antenna situated at the foci of the 4Pi configuration is employed to obtain the required illumination at the pupil plane for creating the above optical needle through the use of a time-reversal holographic methodology. Numerical results show that the spatial polarization direction of the created optical needle is consistent with that of the spatial ULS antenna, that its length is approximately equal to the length of the ULS antenna, and that the transverse size of the optical needle is $\sim 0.36\lambda$ over its extent. The proposed method is more flexible than traditional methods for customizing the optical needle with prescribed characteristics.

KEYWORDS:

• Optical needle
• spatial ULS antenna
• 4Pi focusing system

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 61571271) and the Natural Science Foundation of Fujian Province of China (No. 2021J01972, No. 2020J01777 and No. 2019J01736).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [Grant Number 61571271]; Natural Science Foundation of Fujian Province: [Grant Number 2019J01736,2020J01777,2021J01972].