A programmable optical processor reduces distortion over long fiber links

A September Nature Photonics study places programmable photonic unitary processors at intermediate points in a spatially multiplexed fiber link. The approach adjusts the transmission channel itself instead of leaving all correction to digital processing at the receiver.

The researchers demonstrate 1,300-kilometer transmission using a three-mode fiber and a gradient-based optimization method. Their optical processors reduce accumulated modal dispersion and the associated digital post-processing burden.

It is an example of photonic computation applied directly to a communication problem. Scaling the approach still requires accounting for insertion losses, control overhead and how the optimized settings respond to a changing transmission environment.