An Er-doped all-fiber ultrashort pulse laser with positive total net-cavity group-velocity dispersion is demonstrated based on a hybrid mode-locking mechanism ensured by single-walled carbon–boron–nitrogen nanotubes with coaction of the nonlinear polarization evolution effect. The generation regime with a similariton-like spectrum is obtained. The spectrum width is ~31.5 nm, and the minimal pulse duration is ~294 fs at full width at half maximum. The average output power is ~3.2 mW, corresponding to 0.376 nJ pulse energy and 1.25 kW peak power. The fundamental pulse repetition rate is ~8.5 MHz, with a signal-to-noise ratio of 60 dB. The standard deviation of average output optical power stability, measured for 12 h, is about ~1% RMS, and the maximum level of relative intensity noise (RIN) does not exceed <−120 dBc/Hz in the 30 Hz–1 MHz frequency range. To prove the similariton-like regime generation, we also studied numerically and experimentally the pulse evolution during propagation through a laser resonator and output single-mode fiber with anomalous dispersion.

We report on a scalable chirped-pulse Er-doped all-fiber laser, passively mode-locked by single-wall carbon nitride nanotubes. The average output power is ~15 mW, which corresponds to a peak power of ~77 W, and pulse energy of ~1.9 nJ and was achieved using a single amplification stage. We observed chirped-pulse generation with a duration of ~24.6 ps at a relatively low repetition rate of ~7.9 MHz, with a signal-to-noise ratio of ~69 dB. To characterize the short-term stability of the obtained regime, we have measured the relative intensity noise of the laser, which is <−107 dBc/Hz in the range of 3 Hz–1000 kHz. It should be noted that the standard deviation of root mean square of average power does not exceed a magnitude of 0.9% for 3 h of measurement.

Subject of study . The formation process of high-order bound soliton groups (soliton molecules) in an all-fiber erbium-doped ring laser operating in the mode-locking regime is investigated. Aim of study. The aims of this study are to develop a numerical model that reveals the mechanisms underlying the generation of high-order soliton molecules and to determine the influence of key resonator parameters of a femtosecond fiber laser on the formation of stable multi-pulse states. Method. A numerical approach based on coupled nonlinear Schrödinger equations was employed. The equations were solved using the split-step Fourier method while accounting for refractive index nonlinearity, gain saturation, and polarization effects. The simulations considered the configuration of a fully fiber erbium-doped ring laser with a highly nonlinear fiber incorporated into the resonator. Main results. A stable solution of the Schrödinger equation corresponding to more than ten bound pulses was obtained, confirming the feasibility of generating high-order soliton molecules. The high gain of the active medium was the primary factor responsible for the splitting of the initial pulse into multiple bound solitons, while polarization effects and phase delays provided fine control over the number of pulses and their temporal separation. The obtained results were well aligned with experimental data and the theory of energy quantization in femtosecond fiber lasers. Practical significance. The proposed numerical model can be used to optimize and improve fiber lasers for application in quantum computing and optical communications.

We present a chirped pulse erbium-doped all-fiber hybrid mode-locked laser as a source of high-energy probe pulses in a Raman distributed temperature sensor with high spatial resolution.