Overview

The recent advent of coherent digital optical transmission has increased the native capacity of a fiber optic link tenfold, versus a transmission modulation of simple on/off such as in 10G WDM networks. Coherent transmission modulation encodes information via phase and polarization, and the permutations of these variables are many times greater than on/off keying. The main photonic modules required for coherent optical communications are transmitters, receivers, and where the network is branched, optical switches. Transmitters and receivers are often combined into single modules which are called transceivers. To create a detectable error-free signal in the coherent modality requires that each color (wavelength) transmitted be much purer than for lower-speed protocols. The primary enabler of ultra-narrow linewidth (NLW), that is, ultra-pure color, is a new generation of the most advanced lasers. These NLW lasers must be paired with a new generation of receivers that decode phase and polarization through comparison with another NLW laser in a PIC-interferometer. Ultra-narrow linewidth lasers are built on Indium Phosphide substrates while the receivers utilize a Silicon or Indium Phosphide interferometer and Indium Phosphide photo detectors. These 100G and beyond coherent optical transmission devices require tighter tolerances of material thickness and other critical dimensions than do components operating at 10G. For 100G, a new generation of technologies is required to suitably process transmission signals in both the laser transmitter or the detector and receiver. As transmission speeds move to 200G and 400G through higher order modulation protocols and higher symbol rates, even higher performance optical components are required. Today, NeoPhotonics is a market share leader for key products used in coherent 100G transmission, including Integrated Coherent Receivers (ICRs) and Narrow Linewidth Tunable Lasers (NLW-TL). NeoPhotonics is further offering new generations of pluggable coherent modules which combine its NLW-ITLA with its ICR with and a coherent modulator. NeoPhotonics’ first such product is a new CFP2-ACO module, which is currently available in a Class-3 configuration.

For switching in Coherent Systems, NeoPhotonics also offers Multicast Switch products the roll out of Colorless, Directionless, Contentionless switching. The need to eliminate contention is being driven by the move to “software-defined networks” or SDN, which is important to both telecom network requirements and content provider networks. A “contentionless” architecture uses both traditional “Wavelength Selective Switches” and a new “Multicast Switch”, which is supplied by NeoPhotonics. As one or more multicast switches are deployed initially with each ROADM node, and then additional multicast switches are deployed over time as traffic growth demands, networks are enabled to expand as needed.