Enhancing Carrier Suppression in Radio-over-Fiber Links Using Sagnac Loop Techniques

Abstract

We present an optimized technique to improve the optical carrier-to-sideband ratio (OCSR) in a radio-over-fiber (RoF) link using a Sagnac loop configuration. Improving OCSR is important for better power efficiency and efficient bandwidth usage in modern communication systems. The proposed system consists of a Sagnac loop integrated with a LiNbO₃ modulator and a polarization splitter. To optimize OCSR, key performance parameters such as extinction ratio (ER), spurious-free dynamic range (SFDR), bit error rate (BER), error vector magnitude (EVM), and signal-to-noise ratio (SNR) are analyzed. Results show that increasing ER plays a major role in enhancing optical carrier suppression. The Sagnac-based RoF system improves SFDR by more than 19 dB over a wide range of radio frequency (RF) frequencies. Although SNR slightly reduces due to power fading compensation, overall system performance improves significantly. Compared to conventional Mach–Zehnder modulators, the proposed design achieves better performance, with an EVM of 12.31%, BER of 0.4765 at high RF power, and a peak SFDR of 113.34 dB·Hz^2/3 at 20 GHz.

Received: 23 October 2024 | Revised: 6 August 2025 | Accepted: 24 July 2026

Conflicts of Interest

The authors declare that they have no conflicts of interest to this work.

Data Availability Statement

Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Author Contribution Statement

Archa Chandrasenan: Conceptualization, Methodology, Formal analysis, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization. S. J. Anshula Vijayam: Software, Supervision, Project administration. Joseph Zacharias: Validation, Investigation.