NEC sets long-haul subsea cable record

Japan’s NEC has announced it has become the first vendor to achieve a transmission capacity of over 50Tbps over a distance greater than 10,000km using a single optical fiber.

The new development could pave the way for significantly faster subsea cables spanning trans-Pacific distances, helping the industry meet surging traffic demands in the APAC region.

NEC has demonstrated a speed of 50.9Tbps over a more than 11,000km span of cable using new C+L band erbium-doped fiber amplifier (EDFA) technology. The company said the performance translated to a record-breaking capacity of 570 petabits per second per kilometer.

To push the capacity of the cable to close to the Shannon Limit – the spectral efficiency limit of optical communications, NEC researchers developed a new multilevel, linear and nonlinear constellation optimization algorithm.

With this algorithm, NEC has achieved an optimized 32 quadrature amplitude modulation (32QAM) constellation with a higher nonlinear capacity limit and an unprecedented spectral efficiency over a trans-Pacific distance.

In addition, NEC researchers developed a new bi-directional amplifier design to help maximize the capacity per fiber pair by reducing effective noise and device complexity.