Compact, high repetition rate ( ∼ G H z level) femtosecond fiber lasers are attractive for high-precision, high-speed scientific and engineering fields. However, the noise of such a laser seems far higher than low repetition rate ones, which limits its application. Motivated by this challenge, we combined the solid state and the fiber laser into a novel and highly stable “solid-state fiber laser” operating at 840 MHz repetition rate. Benefitting from the robust architecture of “optical cubes,” the laser shows an ultralow timing jitter (130 as) in free-running operation. This is the first time the timing jitter of a high repetition rate fiber laser has been brought to the attosecond level, to the best of our knowledge. This breakthrough makes an impact on the concept that the high repetition rate is associated with high timing jitter in fiber lasers and opens the way for real-world applications of these lasers.

Establishing relations between fundamental effects in far-flung areas of physics is a subject of great interest in the current research. Realization of a novel photonic system akin to the radio-frequency superconducting quantum interference device (RF-SQUID), in a fiber laser cavity with epsilon-near-zero (ENZ) nanolayers as intra-cavity components is reported here. Emulating the RF-SQUID scheme, the photonic counterpart of the supercurrent, represented by the optical wave, circulates in the cavity, passing through effective optical potential barriers. Different ENZ wavelengths translate into distinct spectral outputs through the variation of cavity resonances, emulating the situation with a frequency-varying tank circuit in the RF-SQUID. Due to the presence of the ENZ element, the optical potential barrier is far lower for selected frequency components, granting them advantage in the gain-resource competition. The findings reported in this work provide a deeper insight into the ultrafast ENZ photonics, revealing a new path toward the design of nanophotonic on-chip devices with various operational functions, and offer a new approach to study superconducting and quantum-mechanical systems.

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We demonstrate a mode-locked 100 MHz Er:fiber laser on “optical cubes”, with which the repetition rate of the laser drifts within 300 Hz over 20 hrs. The measured timing jitter with BOC was 98.4 as.