A General Performance Estimation Framework for Multihop Optical Repeater/Regenerated Links

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Name of the Speaker : Fredy Francis (EE14D020)
Name of the Guide: Dr. Manivasakan R
Date/Time : 28th September 2022, 3.00 pm

The advent of Erbium Doped Fiber Amplifiers (EDFAs) revolutionized optical communication links with its large bandwidth, relatively large gain at low noise figures and crosstalk, polarization insensitivity, high conversion efficiency, and fundamentally - ability to amplify in the optical domain. However, Amplified Spontaneous Emission (ASE) noise accumulation limits the link reach, necessitating the need for regeneration. Although cascaded optical all-repeater/all-regenerator are well researched, the analysis lacks demonstration of unconditional superiority of the latter over the former in terms of BER and the monetization of BER advantage into power saved or extra optical reach for the all-regenerator link over the all-repeater link. Motivated by the above, we propose a simple yet general framework for the performance limit estimation of repeated/regenerated links and demonstrate the same for typical fiber optical and free-space optical links. An abstract model is introduced first, which is then employed to analyze practical amplified(repeated)/regenerated cascaded optical links. Certain approximations to simplify the analysis and computations are also discussed, which should help reduce computational complexity and enable fast decision-making in dynamically reconfigurable optical networks. Further, a multihop Free Space Optical (FSO) link is analyzed using the same and compared against a commercial optical link simulation tool. The same can also be extended to analyzing other multihop links like underwater and satellite optical links.

We also discuss a transfer matrix-based approach to visualize bit probability evolution along the link. This technique is also used to demonstrate the noise suppression characteristics offered by adding a slight nonlinearity to the power transfer function of the optical amplifier. We propose that the same can be used in the jitter analysis of a multihop optical link hence providing a more comprehensive framework for the BER analysis of a multihop optical link.