Abstract
We propose and demonstrate the fabrication of an all-fiber mode converter enabling simultaneous generation of multiple high-order core modes, which is realized by inscribing a helical long-period grating (HLPG) in a few-mode fiber (FMF) using a femtosecond laser. Helical refractive index modulation is introduced by continuously irradiating the core region with a highly focused femtosecond laser, while the fiber moves in a spiral path through a three-dimensional translation stage. Mode conversion from the LP01 mode to high-order core modes, including LP11, LP21, LP31, LP02, LP12, and LP41 modes, is achieved by controlling the inscription pitch of the grating. Moreover, first-, second-, third-, and fourth-order orbital angular momentum (OAM) modes can be directly generated using the HLPGs, and multiple OAM modes of different topological charges can be simultaneously excited using a single high diffraction order HLPG. This approach offers a new option for implementing with high-integration high-order mode converters or OAM mode generators.
| Original language | English |
|---|---|
| Pages (from-to) | 2965-2968 |
| Number of pages | 4 |
| Journal | Optics Letters |
| Volume | 48 |
| Issue number | 11 |
| Early online date | 25 May 2023 |
| DOIs | |
| Publication status | Published - 1 Jun 2023 |
Bibliographical note
Copyright © 2023 Optica Publishing Group. This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: https://opg.optica.org/ol/abstract.cfm?uri=ol-48-11-2965 . Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Keywords
- Atomic and Molecular Physics, and Optics