Few-mode fiber with inverse-parabolic graded-index profile for transmission of OAM-carrying modes

Abstract

A novel type of few-mode fiber, characterized by an inverse-parabolic graded-index profile, is proposed for the robust transmission of cylindrical vector modes as well as modes carrying quantized orbital angular momentum (OAM). Large effective index separations between vector modes (>2.1 × 10(-4)) are numerically calculated and experimentally confirmed in this fiber over the whole C-band, enabling transmission of OAM(+/-1,1) modes for distances up to 1.1 km. Simple design rules are provided for the optimization of the fiber parameters.

Orbital-Angular-Momentum Polarization Mode Dispersion in Optical Fibers

“…Actually the 2 nd order OAM mode was not optimized when we were designing IPGIF. The EH 11 and HE 31 modes are close to cutoff [9] and are more lossy than other modes in IPGIF. Moreover, the 2 nd mode group lies in the strongly normal chromatic dispersion region (<-100 ps/nm/km).…”

“…The first OAM fiber has an inverse-parabolic graded index profile, referred to as "IPGIF" [9]. Its refractive index profile is expressed as: 11 and HE 31 modes are close to cutoff [9].…”

“…The first OAM fiber has an inverse-parabolic graded index profile, referred to as "IPGIF" [9]. Its refractive index profile is expressed as: 11 and HE 31 modes are close to cutoff [9]. Thus the zero and first order OAM mode supported by HE 11 and HE 21 modes respectively are of the most interest for data transmission.…”

Novel Equalization Techniques for Space Division Multiplexing Based on Stokes Space Update Rule

“…The generation of OAM modes can be done by means of ring resonators or its conversion by free space optics employing Spatial Light Modulators (SLM) [15]. OAM modes also require the design of specific optical fibers that are capable of removing aforementioned degeneracy and thus of suppressing mode coupling such as the inverse-parabolic graded-index fiber (IPGIF) [16]. Even though these fibers can prevent mode coupling in theory, the transmission of OAM modes with tolerable crosstalk is only possible for short distances (in the order of a few km [17]) due to the imperfections of the fiber, fiber coupling, and bending.…”

Low-Loss 25.3 km Few-Mode Ring-Core Fiber for Mode-Division Multiplexed Transmission

“…LP1m modes where m is an integer) have been reported both theoretically [12][13][14] and experimentally [15][16][17][18][19][20][21] to show great potential for improving the transmission capacity of MDM system with low DSP complexity. In FM-RCFs, the effective index difference between adjacent neighbouring azimuthal modes significantly increases with increasing azimuthal mode number, which can result in relatively weak mode coupling between higher-order azimuthal modes.…”