Design and fabrication of ultra-low crosstalk and low-loss multi-core fiber: erratum.

This erratum amends typographical errors in Eq. (1) and Table 2Table 2Optical properties of each core of the fabricated MCF.Attenuation [dB/km]MFD [µm]Aeff [µm2]λcc [nm]CD [ps/nm/km]D. Slope [ps/nm2/km]Bend loss (R = 5 mm) [dB/turn]PMD [ps/√km]λ [nm]1550162515501550N/A1550155015501625C + LDesignN/AN/A9.8679.6149623.30.0630.0100.021N/ACore 10.1760.1969.8380.2150922.20.0620.0110.0200.132Core 20.1790.1979.7680.2150022.20.0620.0100.0200.134Core 30.1810.2029.8881.3150422.20.0620.0100.0200.044Core 40.1770.1999.8580.8149822.20.0620.0110.0210.093Core 50.1750.1929.7479.0148522.20.0620.0110.0220.205Core 60.1790.2009.8079.9148322.10.0620.0110.0220.116Core 70.1770.1979.7278.2149822.20.0620.0100.0190.106 in Opt. Express 19, 16576 (2011).

Physical interpretation of intercore crosstalk in multicore fiber: effects of macrobend, structure fluctuation, and microbend.

We have derived an intuitively interpretable expression of the average power-coupling coefficient for estimating the inter-core crosstalk of the multicore fiber. Based on the derived expression, we discuss how the structure fluctuation and macrobend can affect the crosstalk, and organize previously reported methods for crosstalk suppression. We also discuss how the microbending can affect the crosstalk in homogeneous and heterogeneous MCFs, based on the derived expression and previously reported measurement results.

Uncoupled multi-core fiber enhancing signal-to-noise ratio.

We designed and fabricated a low-crosstalk seven-core fiber with transmission losses of 0.17 dB/km or lower, effective areas larger than 120 µm(2), and a total mean crosstalk to the center core of -53 dB after 6.99-km propagation (equivalent to -42.5 dB after 80 km), at 1550 nm. We also investigated the signal-to-noise ratio (SNR) achievable in uncoupled multi-core transmission systems by regarding the crosstalk as a virtual additive white Gaussian noise. The SNR under existence of crosstalk in the fabricated multi-core fiber (MCF) was estimated to be 2.4 dB higher than that in a standard single-mode fiber (SSMF) in the case of 80-km span, and 2.9 dB higher in the case of 100-km span; which are the best values among MCFs ever reported, to the best of our knowledge. The SNR penalties from crosstalk in this MCF were calculated to be 0.4 dB for 80-km span and 0.2 dB for 100-km span. We also investigated SNR penalty from crosstalk in the more ordinary case of an MCF with SSMF cores, and found that the total mean crosstalk to the worst core after one 80-km span should be less than about -47 dB for 0.1-dB penalty, about -40 dB for 0.5-dB penalty, and about -36 dB for 1-dB penalty.

Design and fabrication of ultra-low crosstalk and low-loss multi-core fiber.

We designed and fabricated a multi-core fiber (MCF) in which seven identical trench-assisted pure-silica cores were arranged hexagonally. To design MCF, the relation among the crosstalk, fiber parameters, and fiber bend was derived using a new approximation model based on the coupled-mode theory with the equivalent index model. The mean values of the statistical distributions of the crosstalk were observed to be extremely low and estimated to be less than -30 dB even after 10,000-km propagation because of the trench-assisted cores and utilization of the fiber bend. The attenuation of each core was very low for MCFs (0.175-0.181 dB/km at 1550 nm) because of the pure-silica cores. Both the crosstalk and attenuation values are the lowest achieved in MCFs.