Abstract
The eigenmodes of an inverse-parabolic graded index fiber under torsion were investigated by using the finite element method simulation. These eigenstates correspond to orbital angular momentum modes except for the two polarized-vortex modes. The design of appropriate core parameters can lead to the difference in the effective refractive indexes between all adjacent modes being greater than 10−4 over a bandwidth of 1.5 to 1.6 μm, which is expected to be an ideal method for the generation of multiple vortex modes in few-mode fiber for optical communication. The results showed that the separation of these modes changes with twist rate. Compared to the twisted air-hole ring-core fiber, the optimal twist rate of this fiber was found to be an order of magnitude smaller, which provides a more feasible scheme for the combination of mode division multiplexing and wavelength division multiplexing. We speculate that this study may have promising prospects in various applications such as particle manipulation, imaging, and quantum communication.
Highlights
With increasing demand for effective optical communication capacity, single-mode optical fibers meet a bottleneck for their implementation in quantum communication [1]
The design of appropriate core parameters can lead to the difference in the effective refractive indexes between all adjacent modes being greater than 10−4 over a bandwidth of 1.5 to 1.6 μm, which is expected to be an ideal method for the generation of multiple vortex modes in few-mode fiber for optical communication
Ye et al proposed the use of twisted fiber with a ring core and an air hole to make the effective index difference between adjacent vortex eigenmodes greater than 10−4; the twist rate they applied was so high that it was difficult to realize in practical applications [19]
Summary
With increasing demand for effective optical communication capacity, single-mode optical fibers meet a bottleneck for their implementation in quantum communication [1]. The vortex beam is expected to be used in future communication systems due to its orbital angular momentum (OAM) [3], [4]. The order of the optical OAM is represented by the topological charge, and vortex beams with different topological charges are orthogonal. In order to make (1-b), (1-c), and (1-d) available, it is necessary to use some means to lift the degeneracy among the degenerate scalar modes, such as polarization effects, bending of the optical fiber or the elliptical core [16], [17]. Ye et al proposed the use of twisted fiber with a ring core and an air hole to make the effective index difference between adjacent vortex eigenmodes greater than 10−4; the twist rate they applied was so high that it was difficult to realize in practical applications [19]. Unlike air-hole ring-core fiber, it is easier to weld with other fibers
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
