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.

High repetition rate ultrafast fiber lasers are essential for both scientific research and industrial applications. Here, we report the first, to the best of our knowledge, all-fiber ring laser with a fundamental repetition rate exceeding 1 GHz, by integrating all necessary functions into one single device with commercial active fiber pigtails. Low-threshold self-starting mode-locking is achieved by using a carbon nanotube (CNT) saturable absorber that directly deposits on the Er-doped fiber connector. The laser operates at 1562 nm, delivering 682 fs pulses with 1.028 GHz fundamental repetition rate with good stability, low intensity/phase noise, and high signal-to-noise ratio. The proposed compact source is promising for high repetition rate applications and provides a reference for fiber lasers with different mode-locking mechanisms or in various wavelength ranges. We also provide in-depth discussions on the key challenges and future directions for fiber lasers mode-locking at GHz rates using real saturable absorbers.

Coherent and flat supercontinuum (SC) sources are demanded for applications of metrology, spectroscopy, and bio-imaging. However, the process of SC generation is usually very complicated. We demonstrated a convenient and efficient method based on a genetic algorithm (GA). According to an objective spectrum, this algorithm could reverse-design the geometry of a fiber or waveguide without knowing the specific non-linear processes involved. Using this method, we designed a dispersion-managed photonic crystal fiber (PCF) for SC generation at 1 GHz comb spacing. With an input pulse of ∼150 fs, 450 pJ at 1050 nm, a 3 dB fluctuation spectrum ranging from 510 nm to 850 nm is obtained, which is absolutely fit to the calibration of an astronomical spectrograph.

We demonstrated a 100-MHz Er-doped fiber laser mode locked by nonlinear amplifying loop mirror with low timing jitter on the “optical cubes” structure. The laser employed an all polarization-maintaining configuration. To guide the experimental construction, a numerical simulation of the laser was implemented via the generalized nonlinear Schrödinger equation and Jones matrices. The laser configuration with the optimal output performance was adopted in the experiment. With the contribution of the “optical cubes” structure, the laser exhibited a good repetition frequency ( $\bm {f}_{\boldsymbol{r}}$ ) stability. The root-mean-square (RMS) free-running $\bm {f}_{\boldsymbol{r}}$ drift was 106.72 Hz without temperature control over 20 hours. In free-running operation, the short–term overlapping Allan deviation of $\bm {f}_{\boldsymbol{r}}$ at 1 s reached the level of $\bm {4.47 \times 10^{-10}}$ . Furthermore, utilizing the balanced optical cross-correlator method, we measured the timing jitter for the direct output from the laser without amplification and pulse compression. The free-running RMS timing jitter was as low as 99.63 as in the integration range of 10 kHz to 1 MHz. The dominant noise source was analyzed with well-established analytic model.

We demonstrated what is believed to be the first 1.2 GHz nonlinear polarization rotation stretched-pulse mode-locked Yb:fiber laser with a compact design and innovative components. With a compact Faraday rotation angle has been used in NPR mode-locked lasers, and we find that incomplete isolation of backward-propagating light does not hinder self-starting. This laser directly outputs sub-40 fs pulses with a spectral bandwidth exceeding 70 nm, achieving over 1 W of average output power. The laser serves as a seed source, generating a supercontinuum over one octave-spanning range without external amplification or compression.

We demonstrate a compact astro-comb with ~30 GHz line spacing covering the 560–900 nm range, seeded by a 1 GHz Yb:fiber laser frequency comb phase-locked to a rubidium clock for long-term frequency stability. The comb spacing is multiplied by a passively stabilized Fabry–Pérot cavity, which is vacuum-sealed (3.3 × 10⁻⁵ Pa) and temperature-controlled at 25 ± 0.05 °C, exhibiting a resonance linewidth of 80.56 MHz. Characterization using a high-resolution Fourier-transform spectrometer reveals sharp, evenly spaced comb lines with a maximum side-mode suppression ratio of 23.86 dB. The estimated radial velocity (RV) precision reaches ~63 cm/s, and further reduction in measurement noise is expected to achieve <10 cm/s precision, meeting the stringent requirements of next-generation astronomical spectrographs.