We demonstrate a single-ended colorless coherent receiver using symmetric 3x3 couplers for optical hybrids. We show that the receiver can achieve colorless reception of fifty-five 112-Gb/s polarization-division-multiplexed quadrature-phase-shift-keyed (PDM-QPSK) channels with less than 1-dB penalty in the back-to-back operation. The receiver also works well in a long-haul wavelength-division-multiplexed (WDM) transmission system over 2560-km TrueWave® REACH fiber.
by point followed by differentiation of the obtained curve to determine the dispersion in the complete spectral range. Single-shot measurements were used not only to determine the dispersion and its slope at a particular wavelength, but also for dispersion curve measurements over a wide spectral range. The setup therefore provides a simple and fast, but at the same time accurate and reliable method, for dispersion evaluation applicable to any fiber types.The measured dispersion curves of a 60-cm-long piece of dispersion-compensating fiber (DCF) placed in a coil for a number of bending diameters are shown in Fig. 3. The bending effects the value of the dispersion, slope, and also the shape of the curve. The results are well explained by theoretical modeling and are of importance not only for application but also for design optimization of DCF. *Lucent Denmark A/S, Priorparken 680, Brondby 2605, Denmark 1. L.G. Cohen, IEEE J. Lightwave Technol. 3,958 (1985). 2. S.V. Chernikov, Y. Zhu, J.R. Taylor, V.P. Gapontsev, Opt. Lett. 22, 298 (1997).Several groups have now demonstrated the efficiency of the dispersioncompensating fiber (DCF) for wide-band compensation of the dispersion at 1550 nm of standard nonshifted telecommunication fibers. For example, simultaneous transmission of eight $0-Gbitls channels over 240 km of standard single-mode fiber was recently demonstrated using DCF.'The capability of making DCF has now been demonstrated by several groups?-5 We report for the first time, to our knowledge, results of large volume production of more than 10000 km of DCF. This is equivalent to more than 1000 modules, which each can compensate 60 km of standard fiber.The index profile used is shown in Fig. 1. It has a narrow high-index core surrounded by a deeply depressed trench followed by a lightly raised ring. A high core index IN favorable as it enables a high negative dispersion, but the drawback is increased attenuation. The choice of core TuD5 Table 1. Results of More Than 10000 km of DCFdiameter is a compromise as well. Decreasing the core diameter decreases the dispersion, but increases the bend loss sensitivity. The deeply depressed trench decreases the dispersion and is necessary to obtain a negative dispersion slope around 1550 nm.3,4 Negative dispersion slope is essential for use of DCF for wavelength-division multiplexing applications.' Increasing the index of the ring decreases the bend loss sensitivity, but increases the cut-off.Reproducible large volume production of DCF is a difficult task. The design is very sensitive towards small variations in the index profile. For example, we find for our design that a 1% variation of either the core diameter or core index results in a change in dispersion of 5 and 2.5% respectively. Another challenge is to obtain low polarization-mode dispersion (PMD). DCF are more than one order of magnitude more sensitive to core ovalities than conventional telecommunication fibers due to the high core index Therefore extreme care has been taken to avoid core ovalities. At the same ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.