Widely-tunable optoelectronic oscillator using a microfiber coupler Sagnac loop

Abstract

An optoelectronic oscillator (OEO) integrating a Microfiber Coupler Sagnac loop and a parallel optical amplifier is proposed for the generation of wide-range, stable microwave signals. Unlike conventional OEOs that rely on dual-loop configurations, fixed optical delay lines, or bulky and lossy external filters, our design offers a solution capable of generating RF signals over a broad frequency range of 5–20 GHz. Sagnac loop provides high-resolution spectral filtering and substantial side-mode suppression, while the parallel optical amplifier enhances the loop gain and facilitates the stable oscillation across the entire tuning bandwidth. Our results confirm multi-tone microwave signal generation with a side-mode suppression ratio exceeding 50 dB. The single sideband phase noise of about ? 125 dBc/Hz at 10 kHz offset frequency is achieved for 10 GHz oscillation frequency. This hybrid architecture leads to highly stable, tunable, and pure microwave signal generation, making it suitable for radar systems, high-speed communication, and advanced sensing applications. © The Author(s), under exclusive licence to The Optical Society of India 2025.