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. 2025 Jul 22;122(29):e2502921122.
doi: 10.1073/pnas.2502921122. Epub 2025 Jul 17.

Bistable random momentum transfer in a linear on-chip resonator

Tingyi Gu #  1   2 , Lorry Chang #  1 , Jiagui Wu  2   3 , Lijun Wu  4 , Hwaseob Lee  1 , Young-Kai Chen  5 , Masudur Rahim  1 , Po Dong  5 , Chee Wei Wong  2   3
Affiliations

Bistable random momentum transfer in a linear on-chip resonator

Tingyi Gu et al. Proc Natl Acad Sci U S A. .

Abstract

Optical switches and bifurcation rely on the nonlinear response of materials. Here, we demonstrate linear temporal bifurcation responses in a passive multimode microresonator, with strongly coupled chaotic and whispering gallery modes (WGMs). In microdisks, the chaotic modes exhibit broadband transfer within the deformed cavities, but their transient response is less explored and yields a random output of the analog signal distributed uniformly from "0" to "1." Here, we build chaotic states by perturbing the multimode microring resonators with densely packed silicon nanocrystals on the waveguide surface. In vivo measurements reveal random and "digitized" output that ONLY populates around 0 and 1 intensity levels. The bus waveguide mode couples first to chaotic modes, then either dissipates or tunnels into stable WGMs. This binary pathway generates high-contrast, digitized outputs. The fully passive device enables real-time conversion of periodic clock signals into binary outputs with contrasts exceeding 12.3 dB, data rates of up to 107· bits per second, and 20 dB dynamic range.

Keywords: TEM; chaotic states; random number generator; silicon nanocrystals; silicon photonics.

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Conflict of interest statement

Competing interests statement:The authors declare no competing interest.

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