WaveLogic 3 Coherent Optical Processors

Why coherent?

Demand for high-bandwidth services is increasing at exponential rates. Coherent optical processing lays the foundation for increasing bandwidth from 10G to 40G to 100G and beyond. It offers the ability to make the network more programmable and unlocks new network architecture possibilities.

Rate 10G 40G 100G
Bit interval (ps) 100 25 10
Electrical bandwidth (GHz) 10 40 100
Optical Spectrum Speed (nm) 0.1 0.8 2
CD Tolerance 1 1/16 1/100
PDM Tolerance 1 1/4 1/10
Impact to Reach from Non-Linearities 1 1/4 1/10

Coherent technology, with a local oscillator approximately centered on the signal’s frequency band, provides a 4.3dB improvement in noise tolerance over traditional direct detection.

The most important characteristic of a coherent receiver, access to the optical electrical field (E-field), provides access to amplitude, phase and polarization information; one can now increase transmission rates via advanced modulation techniques which use multiple bits per symbol. Digital signal processing techniques can now also be used to fully compensate for linear degradations from optical filtering, chromatic dispersion, polarization mode dispersion, and polarization dependent loss.

The spectral selectivity characteristic of a coherent receiver allows further capacity scaling using coherent demultiplexing of multiple carriers. It also enables new, more flexible photonic architectures such as an elegant colorless architecture with minimal optical filtering.

With coherent technology, one can overlay 40G/100G on 10+ year-old systems that had been engineering for 10G IMDD, and reap the benefits of increased spectral efficiency with minimal network investment.