Cable Cutoff Research Articles

Modeling and experiments of O-band transmission over G.654.C optical fiber.

We address the potential application of G.654.C optical fiber for O-band transmission in the wavelength range of 1270 nm to 1330 nm. Fiber samples at the extreme upper end of the cable cutoff manufacturing distribution are chosen for modeling and experimentation. Modeling of multipath interference (MPI) generation in bend conditions representative of cable deployment suggests minimal to negligible penalty and transmission experiments at 100 Gb/s and 400 Gb/s with commercial IMDD transceivers demonstrate longer transmission with increased power margin compared to standard G.652 fiber due to lower O-band attenuation and no adverse impacts from MPI.

Examination of Potential Terrestrial System Effects From Raman Pumps Below Cable Cutoff in G.654.E Fibers

ITU G.654.E was recently approved as a new optical fiber standard for terrestrial systems. While G.654-compliant fibers have been used extensively in undersea submarine networks for some time, the G.654.E standard is optimized for terrestrial systems and, in particular, it enables the use of large effective area fibers to extend the reach of new high data rate signals with multilevel modulation formats. The new G.654.E fiber standard increases the maximum cable cutoff wavelength specification to the lower edge of the C- band, 1530 nm. We analyze potential signal impairments that may arise from Raman amplification with pump wavelengths below cable cutoff. We study the case where Raman pump relative intensity noise (RIN) is caused only by Raman pump multipath interference and show that its effect is negligible compared to the contribution from inherent Raman pump RIN that is constant along a fiber propagation length. We find negligible effects are expected even under worst-case condition.

Measurements and modeling of multipath interference at wavelengths below cable cut-off in a G.654 optical fiber span.

Transmission below the cable cut-off wavelength may be a concern in some systems, especially for an optical supervisory channel (OSC) operating below the signal transmission band in systems built with G.654 fiber. In this work, we constructed a cabled span of G.654-compliant fiber and measured the multipath interference (MPI) generated during propagation through the span at a range of wavelengths below the cable cut-offs of the constituent fibers. Measurements were made under a range of conditions including different splice losses and the presence or absence of higher order mode filters placed around the splices. MPI levels were found to be sufficiently low at wavelengths far below the average cable cut-off such that OSC transmission was penalty-free. We compare the experimental results to modeling predictions and find very good agreement.

Design and optimization of 32-core rod/trench assisted square-lattice structured single-mode multi-core fiber.

We propose and design a kind of heterogeneous rod-assisted and trench-assisted multi-core fiber (Hetero-RA-TA-MCF) with 32 cores arranged in square-lattice structure (SLS), and then we introduce the design method for Hetero-RA-TA-MCF. Simulation results show that the Hetero-RA-TA-32-Core-Fiber achieves average effective area (Aeff) of about 74 μm2, low crosstalk (XT) of about -31 dB/100km, threshold value of bending radius (Rpk) of 7.0 cm, relative core multiplicity factor (RCMF) of 8.74, and cable cutoff wavelength (λcc) of less than 1.53 μm.

Design and optimization of 3-mode×12-core dual-ring structured few-mode multi-core fiber

We adopt dual-ring structure (DRS) for the core arrangement of 3-mode (LP01, LP11a and LP11b)×12-core few-mode multi-core fiber (FM-MCF) and then introduce the design method for this DRS-FM-MCF. After investigating the characteristics such as differential mode delay (DMD), inter-core crosstalk (XT), threshold value of bending radius (Rpk), relative core multiplicity factor (RCMF) and cable cutoff wavelength (λcc), we present an optimized scheme for this DRS-FM-MCF. For the optimized DRS-FM-MCF, |DMD| is ≤100ps/km over C+L band, the maximum XT at wavelength (λ) of 1625nm achieves −33dB/100km, maximum Rpk is 11.03cm, RCMF (LP01, LP11a and LP11b) reaches 25.49 and maximum λcc is ≤1530nm. Compared with one-ring structure (ORS), DRS has much more space to enlarge core pitch (Λ) so that lower XT can be achieved. Furthermore, DRS has less confinement degree on mode than square-lattice structure (SLS) if Λ and cladding diameter (Dcl) are set at similar values. It means that it is easier for DRS to make sure λcc would not be larger than the lower limit of C+L bands. In this paper, DRS is proved as a suitable core arrangement for 3-mode×12-core FM-MCF.

An Efficient Core Selection Method for Heterogeneous Trench-Assisted Multi-Core Fiber

We introduce an efficient core selection method for heterogeneous trench-assisted multi-core fiber. In order to make the design more flexible, the relative position and the width of one trench are usually assumed to have a proportional relation to core radius. However, it is hard to choose non-identical cores simultaneously, since cores are selected under the requirement of cable cutoff wavelength of higher order mode that is influenced by the surrounding trenches, whose relative position and width are also decided by core radii. Therefore, in this method, we first decide the cores at the outer layer and second obtain a core selection region for cores at the inner layer with the outer cores fixed. Both outer and inner cores are designed to achieve the target effective area and crosstalk.

Heterogeneous trench-assisted few-mode multi-core fiber with graded-index profile and square-lattice layout for low differential mode delay.

We propose a kind of heterogeneous trench-assisted graded-index few-mode multi-core fiber with square-lattice layout. For each core in the fiber, effective area (A(eff)) of LP(01) mode and LP(11) mode can achieve about 110 μm(2) and 220 μm(2). Absolute value of differential mode delay (|DMD|) is smaller than 100 ps/km over C + L bands, which can decrease the complexity of digital signal processing at the receiver end. Considering the upper limit of cladding diameter (D(cl)) and cable cutoff wavelength of LP(21) mode in the cores located at the inner layer, we set core pitch (Λ) as 43 μm. In this case, D(cl) is about 220.4 μm, inter-core crosstalk (XT) is lower than -40 dB/500 km and the relative core multiplicity factor (RCMF) reaches 15.93.

Achievable capacity improvement by using multi-level modulation format in trench-assisted multi-core fiber system

We evaluate the impacts of using multi-level modulation formats on the transmission capacity of the multi-core fiber (MCF) having trench-assisted index profile and hexagonal layout. For this evaluation, we utilize the spectral efficiency per unit area, defined as the spatial spectral efficiency (SSE). The results show that the SSE improvement achievable by using the higher-level modulation format can be reduced due to its lower tolerance to the inter-core crosstalk. We also evaluate the effects of using large effective area on the transmission capacity of the trench-assisted MCF. The results show that the use of large effective area can decrease this capacity due to the increased inter-core crosstalk and lengthened cable cutoff wavelength, although it can help increase the transmission distance. Thus, it is necessary to optimize the effective area of MCF by considering both the SSE and transmission distance. However, the results indicate that the effect of using different effective areas on the SSE-distance product is not significant, and it is not useful to increase the effective area of the trench-assisted MCF to be larger than ~110 μm(2).

Single-Mode Photonic Crystal Fiber Design With Ultralarge Effective Area and Low Bending Loss for Ultrahigh-Speed WDM Transmission

We propose a new photonic crystal fiber design with a W-shaped effective index profile to achieve the largest effective area ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> ) for telecommunication use. We realized a 220-μ m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> while achieving both a cable cutoff wavelength of less than 1300 nm and a bending loss compatible with ITU-T recommendations G.655 and G. 656.

Coherent Multipath Interference in Bend-Insensitive Fibers

We present the first comprehensive study quantifying, both theoretically and experimentally, the impact of splice/connection losses on coherent multipath interference (MPI) experienced in bend-insensitive fibers (BIFs) deployed in fiber-to-the-home networks. To guarantee the relevance of our study with respect to system constraints, we systematically investigate the worst-case scenario, i.e., fibers under tests are 2 m long and purposely chosen to exhibit extreme cable cutoff wavelengths (close to the G.652.D upper limit of 1260 nm). We report good agreements between theoretical and experimental results and show that all-solid single-trench-assisted BIFs are highly tolerant to splice-induced MPI.

Accurately predicting the cutoff wavelength of cabled single-mode fiber

A less conservative and more accurate prediction of the cabled-fiber cutoff wavelength was achieved by considering cabling-induced curvature effects (macrobend). Maximum cutoff wavelength shifts of 22 nm (depressed) and 50 nm (matched) were observed for common loose tube cable designs. A comparison between the simulated and measured cable cutoff wavelength (FOTP-170) shows good correlation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>