Long-Term Stability Enhancement in Multi-Cavity Optoelectronic Oscillators via Multicore Fibers

We report a novel multi-cavity Vernier optoelectronic oscillator (OEO) approach enabled by dispersion-engineered heterogeneous multicore fibers (MCFs) to achieve broadband tunability, ultra-low phase noise, and high temporal stability. By using the Central Limit Theorem, we theoretically demonstrate that the temporal stability of the oscillation frequency improves as the number of cavities increases, with the frequency drift variance scaling inversely with the number of cavities. This key insight transcends Vernier-specific implementations, offering a universal framework for enhancing stability in multi-cavity OEOs of varying topologies. Experimental validation using a custom-fabricated 7-core MCF demonstrates up to a 75% reduction in the frequency drift standard deviation for a 7-cavity OEO compared to a dual-cavity configuration, alongside an average phase noise level of approximately −120 dBc/Hz at a 10-kHz offset. By exploiting the phase-to-intensity modulation conversion to implement a broadband radiofrequency filtering response, we reach wideband optically tunable oscillation frequency from 10 to 18 GHz enabled by the MCF dispersion characteristics. These results position MCF-based multi-cavity Vernier OEOs as a versatile platform for next-generation radar, communications, and sensing systems demanding high spectral purity, long-term operational stability, and fast wideband reconfigurability.