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openaire: EC/H2020/820423/EU//S2QUIP We demonstrate a compact all-fiber Er-doped chirped pulse amplification (CPA) system that can produce ∼344 fs pulses with an average power of up to 1.02 W and a repetition rate of 40.6 MHz at 1.56 μm (corresponding to an energy of 25.1 nJ). The pulse compressor in the CPA system is based on a hollow core photonic crystal fiber which is directly butt-coupled to the silica fiber. A mismatched negative third-order dispersion is used to compensate the accumulated nonlinear phase shift in the amplification process for the first time, resulting in the generation of sub-400 fs pulses from an all-fiber Watt-level Er-doped CPA system. Our system architecture offers a possibility for ultrashort pulse generation from all-fiber Er-doped CPA lasers.

We demonstrate a compact, self-starting mode-locked thulium-doped fiber laser based on nonlinear polarization evolution (NPE), with a fundamental repetition rate of ∼ 344 M H z and a pulse duration of ∼ 160 f s . The generated pulses centered at ∼ 1975 n m have a maximum output power of ∼ 560 m W , corresponding to a pulse energy of ∼ 1.63 n J . To the best of our knowledge, the achieved repetition rate represents the highest value of fundamentally NPE mode-locked fiber lasers at ∼ 2 µ m , while the average output power is also higher than the previously reported 2 µm ultrafast single-mode fiber oscillators. The timing jitter in the integrated range [5 kHz, 10 MHz] and the integrated relative intensity noise in the range [10 Hz, 10 MHz] reach ∼ 35 f s and ∼ 0.009 % , respectively. Our high-performance laser is an ideal candidate for various applications, including mid-infrared frequency metrology and high-speed optical sampling.

openaire: EC/FP7/631610/EU//GrabFast We demonstrate a high-peak-power femtosecond fiber laser system based on single-mode holmium (Ho)-doped fibers. 833 fs, 27.7 MHz pulses at 2083.4 nm generated in a passively mode-locked Ho fiber laser are amplified and compressed to near transform-limited 172 fs, 7.2 nJ pulses with 24.3 kW peak power. We achieve this performance level by using the soliton effect and high-order soliton compression. To the best of our knowledge, this is the first demonstration of sub-200 fs pulses, with peak power exceeding 10 kW from a Ho-doped single-mode fiber laser system without using bulk optics compressors.

openaire: EC/H2020/820423/EU//S2QUIP We report a passively mode-locked fiber oscillator based on thulium-doped large-mode-area (LMA) fiber. Reliably mode-locking soliton operation can be readily achieved after the suppression of the higher-order modes by using mode field adapters in combination with coiling fiber method. The laser delivers 600-fs level pulses at ~\mu \text{m}$ with an average power of up to 243 mW and a repetition rate of 53.7 MHz. The output corresponds to a maximum pulse energy of 4.5 nJ, >5 times larger than that of a similar homemade mode-locked Tm laser with the LMA fibers replaced by single mode fibers, coinciding with theoretical prediction. The successful demonstration of our soliton mode-locked LMA fiber laser at ~\mu \text{m}$ offers another strategy for high performance ultrafast fiber sources at mid-infrared region.