Magic cancellation point for vibration resilient ultrastable microwave signal synthesis.

Loh, William; Gray, Dodd; Maxson, Ryan; Kharas, Dave; Plant, Jason; Juodawlkis, Paul W; Sorace-Agaskar, Cheryl; Yegnanarayanan, Siva · Nat Commun · 2025

basic_science · Level V

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Abstract

Photonically-synthesized microwave signals have surpassed the phase-noise performance achievable by traditional means of RF signal generation. However, for microwave-photonic oscillators to truly replace their RF counterparts, this phase-noise advantage must also be realizable when operating outside of a laboratory. Oscillators are known to be notoriously vibration sensitive, with both traditional RF and optical oscillators degrading sharply in all but the most stationary of environments. We demonstrate here a powerful technique that makes use of a precise frequency difference between two optical signals, termed the magic cancellation point, to suppress the vibration-induced noise upon optical frequency division to the RF. We showcase the cancellation of vibration noise by 22.6 dB, achieving an acceleration sensitivity of 1.5 × 10<sup>-10</sup> g<sup>-1</sup>. Beyond mitigating the effects of vibration, this technique also preserves the excellent phase noise obtained by optical frequency division and reaches -72 dBc/Hz and -139 dBc/Hz at 10 Hz and 10 kHz offset frequencies on a 10 GHz carrier. This technique applies widely to optical carriers of any center wavelength and derived from an arbitrary resonator geometry.