On November 23rd 2011 the Russian Т8 company has conducted successful test on transmitting 40 Gbit/s channels for 2,000 km. There have been no errors during the signal transmission of via the 80-channel PUSK DWDM system. The maximum transmission speed on the full system load is 3.2 Tbit/s.
This demonstration has increased the Russian record on data transmission distance with a channel speed of 40 Gbit/s by 800 km at once! The T8 Company devotes this record to the 60th anniversary of the Moscow Institute for Physics and Technology. The T8 company has been established by MIPT graduates, graduates of Moscow State University, Moscow State Technical University, Moscow Engineering and Physical Institute, Moscow Technical University of Communications and Informatics, who now work for T8 and IRE-Polyus, have been involved in the equipment creation and the test execution.
The experimental communication line has been built on the basis of the PUSK DWDM equipment. For purposes of the research the data transfer system has been assembled; it had 40G aggregating transponders installed at receiving and transmitting nodes, those transponders have been forming spectral channels with a 50 GHz step for transmission via an 80 channel multiplexer. Erbium fiber amplifiers (EDFA) and dispersion compensators (DCU) have been installed at intermediate nodes. Bobbins of the G.652 single-mode optical fiber with a length of 100 km provided by the OFS Company have been installed between amplifiers. Specialists have used precompensation of the chromatic dispersion –160 ps/nm to reduce the phase self-modulation.
Units of aggregating transponders developed by the Т8 company have shown excellent optical characteristics. The critical signal-noise rate value OSNRtol was 11 dB, which is a record. Transponders use the differential phase shift keying algorithm (DPSK), which is insensitive to linear and nonlinear distortions. The DPSK format is less subject to linear and nonlinear distortions than amplitude modulation formats, and the T8’s own multiparametric optimization of the DPSK signal has made is possible to reach record values.
The main result of the testing is the error-free transmission of 40G for 2,000 km. The testing has been done within 48 hours. To measure the reserve of the required OSNR, the line work has been examined when increasing losses at measuring points. The measured reserve of the required OSNR was 9 dB, which allows increasing the distance up to 6,000 km.
The received data proofs that the 40G PUSK equipment is applicable for backbone and area communication lines and allows broadly using the equipment within Russian communication networks.