Spectral characteristics and laser performance of a bulk Tb3+-doped selenide glass were studied at room and liquid nitrogen temperatures. Under pumping with a pulsed 2.94 μm Er: YAG laser the output energy up to 36 mJ at 5.25 μm and wavelength tuning within 5.05–5.55 μm spectral range were demonstrated.

Mid-IR lasing of a Tb3+-doped chalcogenide fiber has been demonstrated. Pumping was performed by a CW Er:ZBLAN laser, emitting at a wavelength of 2.795 µm. Fiber length optimization has made it possible to obtain output power up to 2 mW in the wavelength range of 5.2–5.3 µm at 1.8

It has been shown that the sensitization scheme involving non-radiative energy transfer from Tb3+ to Nd3+ in selenide glass is suitable for pumping a mid-infrared Nd3+ ion laser. Stimulated emission corresponding to a novel laser transition 4I11/2-4I9/2 of Nd3+ ions was demonstrated at liquid nitrogen temperature. Using an intracavity CaF2 prism, the laser was tunable from 5.56 to 6.01 mu m. Output energy up to 16 mJ has been obtained.

Efficient room temperature mid -infrared laser action in a Ce 3+ -doped chalcogenide fiber was demonstrated. The fiber had a doped selenide glass core in an undoped sulfide glass cladding. The pump source was a CW Fe 2+ :ZnSe laser emitting at 4.14 mu m. The optimized fiber length allowed obtaining up to 7 mW of 5.06 mu m output with 17% slope efficiency at room temperature. (c) 2024 Optica Publishing Group

We demonstrate chalcogenide glass fiber lasers emitting at $4.6-5.4 \mu \mathrm{m}$. The fibers had $\boldsymbol{\emptyset} 20 \mu \mathrm{m}$ selenide core with of $\mathbf{T b}^{3+}$ or $\mathrm{Ce}^{3+}$ doping and undoped $\boldsymbol{\varrho} 240-250 ~ \mu \mathrm{m}$ sulfide cladding. The 200 and 7 mW output power with 8 and $17 \%$ slope efficiency was obtained for $\mathrm{Tb}^{3+}$ - and $\mathrm{Ce}^{3+}$-doped fibers respectively.

Recent progress in the fabrication of high-purity chalcogenide glasses [1] opened new possibilities for the development of novel mid-infrared rare-earth doped glass lasers (e.g., based on Pr 3+ , Tb 3+ , and Ce 3+ ) emitting in the spectral range of $4-6\ \ \mu \mathrm{m}$ . The best results up to now have been obtained in high-purity Ce 3+ -doped $\text{Ge}_{20}\text{Sb}_{10}\text{Ga}_{5}\text{Se}_{65}$ glass rods [2]–[5].

This investigation proposes Tb3+ ions as efficient sensitizers of 5-6 & mu;m Nd3+ emission in selenide glasses. Tb3+ ions can be pumped by 2.9 & mu;m Er:YAG as well as by 1.9-2 & mu;m Tm3+ lasers and laser diodes. It was shown, that at room temperature the radiationless energy transfer from Tb3+ to Nd3+ is combined with the reverse process. At liquid nitrogen temperature the energy transfer from Tb3+ to Nd3+ becomes irreversible. The proposed sensiti-zation scheme should allow the development of neodymium chalcogenide glass lasers emitting at-6 & mu;m.

This paper provides an overview of mid-infrared lasers based on rare-earth-ion-doped selenide glasses. Laser action was demonstrated at the transitions between the first excited and the ground levels of Ce3+, Pr3+, Nd3+ and Tb3+ ions. The highest output parameters for bulk glass lasers (over 40 mJ of output energy) and wavelength tuning in the range of 4.6–5.6 microns were obtained with Ce3+-doped glass. The highest output parameters for fiber lasers (150 mW at 5.1–5.3 μm under continuous pumping) were demonstrated with Tb3+ ions. The longest lasing wavelengths for any glass laser and tunability within the 5.56–6.01 µm spectral band were shown with Nd3+ ions in a Tb3+-Nd3+ co-doped system.

A method for preparing high purity rare earth elements (REEs) doped chalcogenide glasses, in which all com-ponents of the charge (Ge, Sb, Ga, Se) and REEs are loaded and subjected to additional purification by combining reactive distillation of germanium and antimony selenides and chemical vapor transport (CVT) of gallium and REE iodides under high vacuum conditions, is proposed. The technique is tested in the preparation of Ga5Ge20Sb10Se65 glass doped with (1-20)center dot 10(19) at center dot cm(-3) Ce, Pr, Nd, Tb, Dy. In the best glass samples, the content of impurities was as following: metals - 0.03-4 ppm(wt), hydrogen - 0.01 ppm(wt), heterogeneous micron sized inclusions < 102 cm(-3). The novel high purity level of Ce3+ and Tb3+ doped glasses made it possible to achieve reproducible practically significant characteristics of laser generation power in the 4.5-5.9 mu m range in bulk samples and optical fibers in pulsed and continuous modes at room temperature.

Energy, spectral and temporal characteristics of a Ce 3+ -doped chalcogenide glass fiber laser continuously pumped by a 4.16 μ m Fe 2+ :ZnSe laser were investigated. Milliwatt level output power was obtained. In case of low Q-factor of the resonator the laser operated at λ = 4.62 μ m corresponding to the narrow peak in Ce 3+ emission spectrum. At higher Q-factor, the lasing wavelength changed to 5.0–5.1 μ m corresponding to the plateau in the gain spectrum. In contrast to Tb 3+ -doped mid-infrared fiber lasers, Ce 3+ -doped fiber laser had no tendency to non-relaxing spike operation.

The paper describes terbium-doped chalcogenide glass fiber lasers emitting up to 150 mW at 5.1-5.4 mu m under CW pumping by a thulium 1.908 mu m fiber laser. Attention is drawn to the temporal dynamics of their radiation and to its dependence on the doping level.

The spectral and temporal characteristics of a Ce 3+ -doped chalcogenide fiber laser pumped by a continuous Fe 2+ :ZnSe laser were investigated in this work.

Glassy chalcogenides AVBVI obtained by solidification of high-temperature melts inherit the polymolecular nature of the melt. The influence of this circumstance on the optical properties of glasses is important for the fabrication of optical fibers and has not been adequately studied. Bulk samples of high-purity As40 – xS60 + x glasses (0 < x < 5) containing less than (1–2) × 10–5 wt

Glassy chalcogenides AVBVI obtained by solidification of high-temperature melts inherit the polymolecular nature of the melt. The influence of this circumstance on the optical properties of glasses is important in connection with the use of optical fibers for fabrication and has not been adequately studied. Bulk samples of high-pure glasses As40 – xS60 + x (0 x 5) with the content of metal and silicon impurities less than 0.1‒0.2 ppm wt., carbon, oxygen, hydrogen compounds – no more than 0.5–1 ppm wt. and optical fibers from them were obtained. The IR spectra of bulk samples 12 cm long and optical fibers up to 15 m long were recorded in the spectral range 1000–2000 cm–1. Absorption bands with maxima near 1950, 1805, 1460, and 1320 cm–1, due to the content of superstoichiometric sulfur in glass, were found in the spectra of bulk samples and fibers, and the corresponding values of the extinction coefficients were determined. The results of the study allow us to consider the As2S3 stoichiometry as a factor that significantly affects the optical characteristics of glass.

Room-temperature laser systems consisting of a 4.6-m pulsed Fe:ZnSe pump laser and different Ce 3+ :Ge 20 Sb 10 Ga 5 Se 65 bulk glasses are demonstrated. The slope efficiency of a Ce 3+ :glass laser reaches 25%, with a maximum output energy of 45 mJ.

The influence of rare earth dopant concentration on selenide laser glass quality was investigated. A problem to be solved was identified – an increase in rare earth doping level leads to optical losses due to light scattering by heterogeneous inclusions and to the decrease of the optical damage threshold. The room temperature laser system consisting of 4.6 μ m pulsed Fe:ZnSe pump laser and Ce 3+ :Ge 20 Sb 10 Ga 5 Se 65 bulk glass was demonstrated. The slope efficiency of Ce 3+ :glass laser with respect to the absorbed pump energy reached 25% with a maximum output energy of 45 mJ.

Recently rare earth doped high purity chalcogenide glasses exhibited laser action in the mid-infrared. New laser transitions of Tb3+, Pr3(+) and Ce3+ ions were demonstrated. Output energies up to 35 mJ were already obtained. This paper compares the properties of Ce3+, Pr3+, Nd3+, Tb3+ and Dy3+ doped selenide glasses in order to reveal their laser potential for bulk and fiber lasers emitting in the 4.5-6 mu m spectral range.

(Pb,Gd)3(Al,Ga)5O12:Ce3+,Eu3+ films have been grown by liquid-phase epitaxy from a supercooled high-temperature solution based on the PbO–B2O3 system. We have measured and analyzed their absorption, photoluminescence, and photoluminescence excitation spectra. The results demonstrate that there is energy transfer from Ce3+ to Eu3+, resulting in Ce3+ luminescence quenching.

The first, to the best of our knowledge, mid-infrared Q-switched Ce3+-doped glass laser is demonstrated. As saturable absorbers, Fe2+:CdSe and Fe2+:CdTe are used for the first time. When Q-switched by Fe:CdSe, the laser operates in a multi-pulse regime with an individual pulse width of 110 ns, centered at λ = 5.20 µm. With Fe:CdTe as saturable absorber, 1-3 giant pulses of 30 ns pulse width are generated at λ = 5.13 µm.