Abstract: The increasing reliance on computationally intensive digital signal processing (DSP) in coherent optical communication systems presents significant challenges in receiver complexity and energy consumption. This thesis investigates semiconductor optical amplifier (SOA)-based optical signal processing as an alternative approach to mitigating transmission impairments through nonlinear optical effects, with the objective of reducing dependence on conventional DSP-based compensation.

The thesis develops and experimentally validates a heuristic SOA model incorporating holding-beam-induced gain compression, enabling improved gain stabilization and low-distortion amplification. It further exploits four-wave mixing in SOAs for optical phase conjugation (OPC), demonstrating efficient conjugate generation with advanced coherent modulation formats up to 56 GBaud. Mid-span OPC experiments establish the potential for simultaneous all-optical compensation of chromatic dispersion and fiber nonlinearities, improving nonlinear tolerance and supporting higher launch powers. Building on these results, an on-demand SOA-based OPC prototype integrating phase conjugation, optical amplification, and transparent transmission is demonstrated using a 448 Gbps polarization-multiplexed 16QAM signal over a multi-span fiber link. Network-level investigations extend the study to OPC placement and residual dispersion compensation in wavelength-routed optical networks.

Collectively, these contributions establish SOA-based optical signal processing as a promising device-to-network approach for mitigating transmission impairments while reducing receiver-side DSP complexity and energy consumption in future high-capacity coherent optical communication systems.

Event Details
Title: Mitigating Digital Signal Processing Load in Coherent Optical Networks Using Semiconductor Optical Amplifiers (PhD Viva Voce)
Date: November 02, 2026 at 11:00 AM
Venue: Google Meet (https://meet.google.com/meet/ast-bbsg-nyw)
Speaker: Ms. Mrudula K (EE19D017)
Guide: Dr. Deepa Venkitesh
Type: PHD seminar

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