No abstract

In this Letter, we theoretically and experimentally demonstrate a new method to generate tunable orbital angular momentum (OAM) by continuously changing the angle of linear polarization of the input light. We use the Fourier series of left- and right-hand projections to prove that the average OAM smoothly varied from l=-1 to l=1 with the angle of LP of input light changing from 0 to π, which is fulfilled by an electrical polarization controller.

The combination of multi-band optical transmission and ITU-T G.654 loss-minimized large-effective-area fibers enables superior network performance in the low-loss C+L wavelength bands. As the maximum cut-off wavelength of the G.654 fiber is increased to 1530 nm, from 1260 nm in the commonly used G.652 fiber, the multi-path interference (MPI) resulting from the interplay between the fundamental LP01 mode and the high-order LP11 mode needs to be considered when expanding the multi-band transmission window to cover the S+E+O bands. In this paper, we study optical layer impairments such as the LP01-LP11 mode coupling induced MPI in G.654 fiber, the negative impact of the stimulated Raman scattering (SRS) on the use of optical supervisory channel (OSC) and optical time domain reflectometer (OTDR) in all fiber types, and the four-wave-mixing (FWM) issue in the Oband transmission over G.652 fiber, and discuss the corresponding mitigation techniques. Extensive measurements of G.654.E fibers are made to evaluate the MPI. For impact of MPI, we include it, along with the nonlinear interference, in the generalized Gaussian noise model to accurately assess the link performance, and mitigation strategies are discussed. Additional considerations of diverse optical link conditions on amplification schemes, link distances, and cost constraints are made for provisioning C+L+S+E+O multiband optical networks with the combined use of both G.652 and G.654 fibers, aiming for the optimal utilization of the multi-band transmission in future ultrahigh-capacity optical networks for a wide variety of applications.

We analyze the mode evolution in mode-selective photonic lanterns with respect to taper lengths, affected by possible mode phase differences varying along the taper. As a result, we design a three-mode orbital angular momentum (OAM) mode-selective photonic lantern by optimizing the taper length with mode crosstalk below −24 dB, which employs only one single mode fiber port to selectively generate one OAM mode.

We demonstrate real-time 24-Tb/s dense wavelength division multiplexing (DWDM) transmission over a 1910-km field-deployed G.654.E fiber link using 24 in-line wide-bandwidth Erbium-doped fiber amplifiers with a widened bandwidth of 6 THz in the cost-effective C-band. The DWDM system consists of 60 100-GHz-spaced 400-Gb/s wavelength channels, modulated with probabilistic constellation shaped polarization-division-multiplexed 16-point quadrature-amplitude modulation and fast-than-Nyquist shaping. This field trial shows the feasibility of achieving a record per-fiber capacity of 24 Tb/s in field-deployed 2000-km-class terrestrial fiber links by using the widened C-band.