An ultrafast thulium-doped fiber laser with stretched-pulse operation has been realized and investigated. The passively mode-locked oscillator emitted 119 fs pulses at a peak wavelength of 1912 nm. A normal-dispersion fiber with a high numerical aperture and small core was used for intracavity dispersion management and external compression. Numerical simulations were performed and are in good agreement with the experimental results.

A high-power thulium (Tm)-doped fiber chirped-pulse amplification system emitting a record compressed average output power of 152 W and 4 MW peak power is demonstrated. This result is enabled by utilizing Tm-doped photonic crystal fibers with mode-field diameters of 35 μm, which mitigate detrimental nonlinearities, exhibit slope efficiencies of more than 50%, and allow for reaching a pump-power-limited average output power of 241 W. The high-compression efficiency has been achieved by using multilayer dielectric gratings with diffraction efficiencies higher than 98%.

We present experimental results of the generation of ultrashort pulses in the 2 µm wavelength region by a fiber Mamyshev oscillator, along with the simulation of the pulse propagation in the cavity. The Mamyshev oscillator emitted pulses with energies of 3.55 nJ at a repetition rate of 15 MHz and optical spectra with bandwidths of 48 nm. The pulses propagated in anomalous dispersive Thulium-doped fiber sections with dispersion compensation sections of normal dispersive fibers.

We report on a high power ultrashort pulse regenerative amplifier system, entirely based on thulium-doped laser materials operating around 1.94 μm. At a repetition rate of 1 kHz the Tm:YAP regenerative amplifier emits pulse energies > 700 μJ, only limited by the damage threshold of the Tm:YAP crystal. The pulses can be compressed to 380 fs at an efficiency of 50 %. Purging of the regenerative amplifier cavity with nitrogen is necessary due to atmospheric absorptions causing long ps pedestals in the autocorrelation.

We have created high-precision, miniaturized, substrate-free filters, based on ion beam sputtering on a sacrificial substrate. The sacrificial layer is cost efficient and environmentally friendly and can be dissolved using only water. We demonstrate an improved performance compared to filters on thin polymer layers from the same coating run. With these filters, a single-element coarse wavelength division multiplexing transmitting device for telecommunication applications can be realized by inserting the filter between fiber ends.