Sergey Burtsev

Multi-path interference noise in multi-span transmission links using lumped Raman amplifiers

The MPI noise was experimentally evaluated, using a calibrated electrical spectrum analyzer, in single- and double-stage lumped Raman amplifiers as well as a 5-span optical transmission link using a cascade of 6 double-stage amplifiers. The experimental procedure was calibrated against a source with known MPI levels. Our experimental and theoretical results for MPI cross-talk agree well in a broad range of Raman net gain values from 2 dB to 26 dB per amplifier. We showed that for a 10-span system with 11 lumped Raman amplifiers and an average span loss of 23 dB, the MPI system penalty was only 0.5 dB/sub 20/Q. These results indicate that MPI does not constitute an impairment for carefully designed Raman amplifiers.

Unrepeatered high-speed transmission systems

We review recent advances in the technologies required for high-speed unrepeatered transmission systems, with a specific focus on distributed Raman amplification. We also report several experimental demonstrations with record capacity and reach combinations.

Semi-analytical modeling and design tool for WDM RZ systems. Validation results

We have developed semi-analytical tools to model and design long-haul dispersion-managed WDM RZ systems. Our approach provides a drastic speed-up of system budgeting compared to conventional modeling based on split-step methods. We have validated our analytical models experimentally and numerically.

8 × 120 Gb/s transmission over a cascade of two spans with a total loss in excess of 120 dB

This paper describes developments in unrepeatered systems architecture which result in a significant reduction of Capital and Operational Expenditures. We report 8 × 120 Gb/s transmission over a cascade of two legacy spans of 303.5 km (59.7 dB) and 342.9 km (60.8 dB).

Four-wave mixing in EDFAs

We study FWM in C- and L-band EDFAs. We observe that FWM efficiency is determined by fiber length and channel spacing. We show that FWM from EDFAs exceeds that from non-zero dispersion-shifted fiber in DWDM system.

150 × 120 Gb/s transmission over 3,780 km of G.652 fiber using all-distributed Raman amplification

Commercial all-distributed Raman system is demonstrated to support real-time error-free transmission of 150 channels × 120 Gb/s at 50 GHz channel spacing over 3,780 km of G.652 fiber with backward Raman pumping.

Advanced unrepeatered systems using novel Raman amplification schemes

Unrepeatered transmission systems provide a cost-effective solution to transmit high capacity channels in submarine networks to communicate between coastal population centers or in terrestrial networks to connect remote areas where service access is difficult. The main goal of unrepeatered systems has traditionally been to achieve the longest reach, however, increasing traffic demands now require unrepeatered systems to support both longer reach and higher transport capacity. As a result, transmission rate of unrepeatered systems has quickly moved from 10 Gb/s to 40 Gb/s or 100 Gb/s. This paper reviews the key basic technologies, with a specific focus on Raman amplification, required for long-reach, high-capacity unrepeatered optical transmission systems. We will discuss novel Raman amplification schemes, enhanced remote optically pumped amplifiers (ROPA), ultra-low loss / large effective area fibers, and coherent transmission with advanced modulation format and high FEC coding gain. We will also report recent experimental demonstrations that show how these technologies have been combined to achieve industry’s leading capacity and reach transmission.