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This study demonstrates that multimode intracavity frequency-doubled lasers can achieve intensity-noise suppression far exceeding predictions from standard partition statistics through longitudinal mode coupling. The author proves mathematically that the nonlinear wave dynamics in the doubling crystal follow a strict dissipation inequality, driving the laser modes toward a constant-intensity state, and confirms this mechanism experimentally in a Nd:YVO4/LBO laser system showing 100-fold noise reduction. The findings suggest a general principle applicable to coupled oscillator systems beyond lasers.
Why it matters
This discovery could enable more stable laser sources for precision applications including optical frequency standards, gravitational wave detection, and quantum information processing. The underlying mechanism may apply broadly to reducing noise in other coupled oscillator systems across physics and engineering.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: Multimode intracavity frequency-doubled lasers can reach states of intensity-noise suppression orders of magnitude beyond the predictions of independent-mode partition statistics. I show that the c{hi}(2) coupled-wave dynamics in the doubling crystal obey a dissipation inequality: a fourth-moment functional of the intracavity intensity decreases monotonically under each forward nonlinear pass, driving the mode ensemble toward a constant-intensity manifold. This per-pass result is a strict Lyapunov inequality, and round-trip simulations show attraction to the same low-M4, nearly constant-intensity state under the full cavity dynamics. I confirm the mechanism in an intracavity frequency-doubled Nd:YVO4/LBO laser, observing a 100x contrast between full and Fabry-Perot-filtered output noise at fixed detector bandwidth, well beyond the sqrt(N/N_f) statistical-averaging baseline. The argument depends only on the algebraic structure of the coupling: a coherent superposition of oscillators that share a quadratic dissipative channel. It therefore points to a general Lyapunov route to intensity-noise suppression in coupled oscillator systems, beyond the intracavity-doubled laser.