26. June 2023

3 Min read

    Contents

      Written by Robert Merki

      CTO of R&M

      More power from light

      Coherent optical communication promises a longer range of light signals for data transmission. At the same time, it increases the capacitance of fiber optics.

      For transmission, an optical beam is split into its orthogonal light polarizations. The phase of one of the polarizations is modulated before being merged again into a single beam. This beam is then transferred via an optical fiber.

      With coherence technology, detection is no longer based solely on measuring the power of the incoming signal. It splits the incoming signal back into its orthogonal polarizations and combines it with a local light source.

      After the recombination and coupling of the beam into the optical fiber, the propagation of light in the network does not require polarization-maintaining fibers or a particular improvement in connectivity.

      A much denser and far-reaching signal can be transmitted over existing fiber optic infrastructures, but the complexity and price of the optical modules increase. It is easy to see that profitability depends on the application.

       

       

      Profitable uses

      The obvious use is in the field of long-haul links. Whereas a repeater used to be required every few dozen kilometers, intercity connections with high bandwidth are now possible with a single coherent module.

      Coherent optical communication can also be used to upgrade the backbone network. It is also suitable for operating backbones for 5G networks.

      Potential for data centers

      A less obvious use is the interconnection of hyperscale data centers and next-generation cloud services. The power of existing data center interconnects on campus or in a conurbation between distributed premises can be increased with coherence technology.

      In this operational area, the coherence solution competes with other technologies that overcome space and bandwidth restrictions. These include multicore fibers. The possibility of using the existing connections is definitely a compelling argument in favor of a coherent solution.

      Demand is increasing

      Several manufacturers have launched products for coherent optical communication and announced comprehensive solutions. In March 2022, the market research company Cignal AI expected sales of corresponding modules to triple in the current year. So we can expect some changes in the architecture and topology of networks.

       

       

      Interesting sources:

      Find out more about R&M solutions for data center interconnects here.

      Coherent optical signal transmission enables direct and high-performance connections, such as data center interconnects. Source: EXFO

       Simplified presentation of communication elements in a regular and coherent network. Graphic: R&M