Ultrafast fiber lasers exhibit high broadband gain per pass, superior thermo-optical properties, and excellent beam quality, making them very suitable for practical use. For simplicity and efficiency, advanced mode-locked oscillator designs which can compete with the amplifier systems are always favorable. Here, we demonstrate a high-peak-power Mamyshev oscillator based on single-polarization, large-mode-area photonic crystal fibers. Using properly arranged filters, the fiber oscillator directly emits pulses with 9 W average power at 8 MHz repetition rate, corresponding to a single-pulse energy exceeding 1 μJ. The pulses are dechirped to 41 fs outside the cavity, leading to a record oscillator peak power as high as 13 MW. With such unprecedented performance, the proposed single-stage oscillator should be very attractive for various applications.

We demonstrate dual-comb spectroscopy in the vicinity of 2 µm wavelength based on a single dual-wavelength dual-comb Thulium-doped fiber laser. The shared laser cavity ensures passively maintained mutual coherence between the two combs due to common mode environmental noise rejection. In a proof-of-principle experiment, the absorption characteristics caused by the water in the optical path that composes the dual-comb spectrometer are measured. The retrieved spectral positions of the water absorption dips match with the HITRAN database.

Pulse dynamics controlling is of great importance for high quality pulse generation in ultra-short pulse fiber lasers. The pulse quality characteristics in terms of pulse duration, energy, chirp profile, tunability, as well as noise feature substantially depend on intracavity pulse propagation dynamics. Here we found that a nonlinear amplifying loop mirror mode-locked thulium-doped fiber laser can switch among enabling operation conventional soliton, stretched-pulse soliton and dissipative soliton regimes only by manipulating an intracavity phase bias device. This provides a simple approach to tailoring ultra-short laser characteristics to different applications.

To consider both high-power handling and blue-extended supercontinuum (SC) generation, a long-tapered photonic crystal fiber is pumped by a high-power laser source. An SC ranging from 390 to 2400 nm with 314.7 W output power is obtained. A spectral component below 960 nm accounts for 36.1% of the total output power, exceeding 113.5 W, with a spectral flatness within 16 dB. To the best of our knowledge, this is the first time an SC coverage of all visible wavelengths with more than 300 W output power has been achieved. This result increases the output power of the SC covering the visible range by a factor of three.

The $f$-to-$2f$ interferometer plays a key role for carrier-envelope phase (CEP) measurement and subsequent stabilization. The CEP measurement typically relies on the application of two optical nonlinearities, namely supercontinuum generation and second-harmonic generation. Then the cascadation of these nonlinearities often leads to signal levels on the order of a few photons per pulse. We experimentally demonstrate that the introduction of optical gain into the infrared arm of an $f$-to-$2f$ interferometer can mitigate this detection bottleneck and improve signal-to-noise ratios by 20 dB compared to purely passive schemes. We further show that this measure allows for residual phase jitters between the carrier and envelope of about 10 mrad, corresponding to record-breaking timing jitters in the single attosecond regime. Moreover, the method appears generally applicable to a wide range of oscillators in the near-infrared and may enable stable CEP locking of mode-locked oscillators that so far have resisted stabilization. Finally, we propose a parametric variant of the active $f$-to-$2f$ interferometer that can be used for laser amplifiers with kilohertz repetition rates and below.