We report a 2 μm ultrafast solid-state $\text{Tm}:{\text{Lu}}_2{\mathrm{O}}_3$ laser, mode-locked by single-layer graphene, generating transform-limited $\sim 410\hspace{0.17em}\text{fs}$ pulses, with a spectral width $\sim 11.1\hspace{0.17em}\text{nm}$ at 2067 nm. The maximum average output power is 270 mW, at a pulse repetition frequency of 110 MHz. This is a convenient high-power transform-limited ultrafast laser at 2 μm for various applications, such as laser surgery and material processing.

Femtosecond mode locking of a Tm-doped Lu₂O₃ ceramic laser is reported. Transform-limited pulses as short as 180 fs are generated at 2076 nm with an average output power of 400 mW and a pulse repetition frequency of 121.2 MHz. An output power up to 750 mW can be reached at the somewhat longer pulse duration of 382 fs. Femtosecond pulse generation is realized in the 2030-2100 nm spectral range. Passive mode locking was achieved using an ion-implanted InGaAsSb quantum-well-based SESAM.

Structural, optical, and spectroscopic properties of novel Tm³⁺:Lu₂O₃ ceramics are studied. The average grain size is determined to be ~0.54-0.56 μm. The absorption spectra show good opportunities for diode pumping at 796 nm and 811 nm. The ceramics have high mid-IR transmittance of up to 7 μm. Strong luminescence lines are measured at 1942 nm, 1965 nm, and 2066 nm. CW laser operation at 2066 nm with an output power of up to 26 W and a slope efficiency of 42% is obtained. Q-switched operation with a pulse duration of 100-150 ns and a repetition rate of 5-10 kHz is achieved.

Highly efficient laser oscillations at 2 μm were investigated in $\mathrm{Tm}\text{:}{\mathrm{Lu}}_2{\mathrm{O}}_3$ ceramics in-band pumped at 1670 nm by a Raman-shifted erbium fiber laser. Both 23 W CW and 15 W active Q-switched oscillations with 40 ns pulse duration and 15–30 kHz repetition rate were achieved in a high-quality beam. The evolution of two generated waves at 1966 and 2064 nm in dependence on pump power was studied.

The refractive index changes which can be induced in the Nd:YVO₄, Nd:GdVO₄ and Nd:KGW high gain laser crystals, when their Nd³⁺ laser active ions are pumped from their ground- to excited- energy levels, have been carefully measured and characterized. By using two complementary optical techniques based on pump-probe interferometry and transient diffraction grating, the electronic and thermal contributions to the observed refractive index variations have been accurately determined and successfully exploited to derive various parameters such as polarizability changes, thermo-optic coefficients and thermal diffusivities.

We quantify the refractive index changes (RIC) in single-mode ytterbium-doped optical fibers induced by optical pulses at 980 nm and, for the first time, report details of the effect dynamics. The RIC dynamics is shown to follow that of the population of the excited/unexcited ion states with a factor proportional to their polarizability difference (PD). The absolute PD value is evaluated in the spectral range of 1460–1620 nm for different fiber samples and is found to be independent on the fiber geometry and on the ion concentration. The PD dispersion profile indicates to a predominant far-resonance UV rather than near-resonant IR transitions contribution to the RIC.