On Directly Modulated Reflective Semiconductor Optical Amplifier with Assistance of Birefringent Fiber Loop

Reflective Semiconductor Optical Amplifiers (RSOAs) are essential devices for the development of new generation networks that rely on the convergence of optical and RF communications. Despite their proven potential for direct modulation, RSOAs’ electro-optic response is limited by their finite bandwidth, which hinders their employment both for signal amplification and modulation at the data rates envisioned by the target applications. In this paper, we elaborate on exploiting a Birefringent Fiber Loop (BFL) to enhance the operation of RSOAs as intensity modulators. We apply a mathematically and computationally reduced model to simulate the RSOA response in the time domain, and correlate it with that of the BFL in the frequency domain. We validate the model’s predictions by an extensive comparison of the simulation against experimental results. The reasonable theoretical findings allow us to establish the employed model as an efficient tool for describing electrically driven RSOA operation and its improvement by means of optical notch filtering. Furthermore, we evaluate and quantify the performance of the scheme and the potential range of RSOA direct modulation capability extension enabled by the BFL, which complies with the experimentally observed trends. The outcomes of this thorough study highlight the BFL supportive role in rendering feasible RSOAs’ direct modulation at data rates beyond those deemed possible by their nominal modulation bandwidth. © 2022 by the authors. Licensee MDPI, Basel, Switzerland