Midspan spectral inversion yields record 40-Gbit/s soliton transmission
Working under the auspices of the European Union Advanced Communications Technologies and Services MIDAS project, a team of researchers has demonstrated 40-Gbit/s soliton data transmission over a single channel. The 400-km field test conducted through commercial lines in Jönköping, Sweden, used no soliton control and had amplifiers spaced every 57 km. The transmitter was a specifically developed modelocked fiber ring laser, and an all-optical polarization-insensitive fiber-based demultiplexer was the receiver. An inverter positioned at the 70-km mark provided dispersion compensation via midspan spectral inversion, in which two in-line fiber distributed-feedback lasers are orthogonally polarized to supply the pump waves required for a polarization-independent spectral inversion.
Peter Andrekson at Chalmers University of Technology (Göteborg, Sweden) says, "Perhaps the most important aspect is that our system has high polarization-mode dispersion (PMD) of 0.3 ps/km(0.5). We have demonstrated experimentally that solitons may become the best choice to enhance capacity when PMD is a major capacity limitation, as it will likely be at high bit rates." Other groups involved in the experiment included the Optoelectronics Research Centre at the University of Southampton (England) and Centro Studi e Laboratori Telecomunicazioni (Torino, Italy). The researchers believe this record optical time-division-multiplexed bit rate for a field trial can be increased by wavelength-division multiplexing.