Coherent optical module
Coherent optical communication is a kind of optical transmission which uses local oscillator light for coherent detection. It uses DSP. It has the ability to reach or exceed a transmission rate of 100 gigabits, requiring only a pair of optical fibers to transmit terabits of data, usually for long-distance applications.
Coherent advantage
The main advantages of the coherent optical module are the built-in DSP chip and electronic dispersion compensation (EDC), which is not available in PAM4. This chip does not need a separate DSP and dispersion compensation module, but uses EDC to improve the power.
Coherent optical devices can be transmitted over distances of up to 1000km, enabling long-distance support without the need for third-party systems. Using techniques used in radio communications, coherent optics can improve receiver sensitivity while maintaining selective tuning, which allows the channel spacing to be close but still separate.
Coherent disadvantage
Although CFP and CFP2 digital coherent optics can work quickly and efficiently, they use more power and cost more when compared to other packages, and these disadvantages can impact total operating costs, posing challenges for companies that need high-quality 100G DWDM pluggable optical modules within their budget.
Another disadvantage of coherent optical modules is that two DSPs from the same vendor will be required at both ends of the link. Different DSPs cannot work together, and in some cases the line card must be the same.
Conclusion
