Synthesis and Laser-Related Spectroscopy of Er:Y2O3 Optical Ceramics as a Gain Medium for In-Band-Pumped 1.6 µm Lasers

Optical Spectra and Gain Properties of Ho3+/Pr3+ Co-doped LiYF4 Crystal

Radiative transition properties of Yb3+ in Er3+/Yb3+ co-doped NaYF4 phosphor

Infrared spectral properties for α-NaYF4 single crystal of various Er3+doping concentrations

Tm3+ doped α-NaYF4 single crystal for 2 μm laser application

Within neodymium-doped laser crystals, the codoping of fluorite-type single crystals with non-optically active buffer ions reveals the possibility for broadband laser operation around 1 μm, which makes these materials appealing for a number of applications such as amplifiers for new generation laser fusion facilities. In this work, a detailed spectroscopic investigation of CaF2:Nd3+ single crystals co-doped with various concentrations of Lu3+ ions is presented. The results show that the Nd3+ emission quantum efficiency increases drastically with the Lu3+ concentration, as a consequence of the replacement of Nd3+–Nd3+ clusters by two predominant types of Nd3+–Lu3+ clusters. These two main Nd3+ emitting centres are characterized in detail by identifying, for the first time to the best of our knowledge, their individual absorption and emission cross-section spectra, along with their fluorescence and radiative lifetimes and respective concentrations. The identification of the two predominant Nd3+–Lu3+ clusters (labelled NL1 and NL2) is carried out at room temperature by carefully choosing the Lu3+ concentration, the time windows used in time-resolved spectroscopy and the excitation or emission wavelength. The determination of the different centre concentrations and respective absorption cross-sections is achieved by comparing selective time-resolved excitation spectra and absorption spectra encompassing contributions from Nd–Nd clusters and the two types of Nd3+–Lu3+ clusters. As the Lu3+ concentration increases, the NL2 centres become predominant and are characterized by an emission peak at 1054 nm and a stronger emission cross-section than that of their NL1 counterparts. Finally, the absorption cross-sections, concentrations and lifetimes are successfully used to calculate the contributions of NL1 and NL2 in the various emission spectra regardless of the Lu3+ concentration or excitation wavelength confirming the consistency of the spectroscopic description.

Cross section spectral distribution of Er3+ electronic transitions in SrGdGa3O7 single-crystal

Growth and spectral properties of Ho3+ doped α-NaYF4 single crystal

Er-doped crystalline active media for ~ 3 μm diode-pumped lasers

Spectral luminescence properties of synthesized transparent nano-glass-ceramics doped with erbium ions are studied. It is shown that, as a result of the secondary heat treatment of nano-glass-ceramics, the width of the luminescence spectrum at half maximum increases more than by 15 nm. Luminescence life-time dependences of erbium ions in studied samples are measured, their absorption cross-sections are determined, and their emission cross-sections are calculated by the McCumber method. Spectral and ultimate information characteristics of erbium-doped fiber amplifiers based on synthesized nano-glass-ceramics are numerically simulated. It is shown that, in the unsaturated gain regime, a substantial ripple of the absorption and emission cross-section spectra and shorter lifetime of the metastable level of the erbium ion reduce the pumping radiation power that is required for obtaining the given peak gain, narrow the gain spectra, and lower the transmission capacity of devices based on nano-glass-ceramics compared to the initial glass. Conversely, fiber amplifiers based on calcium fluoride glass-ceramics, for which the lifetime of the metastable level increases with increasing annealing temperature, have an advantage in the transmission capacity over devices based on the primary glass.

Investigating the structure-sensitive factors relevant to cryogenic laser operation of Yb3+ ions in oxide crystals

This work reports on optical spectra of Na5Lu9F32 single crystals doped with various Er3+ concentrations from 0.5 to 5 mol%. In our improved Bridgman method, the X-ray powder diffractions were investigated and optical parameters were also calculated by the Judd–Ofelt theory. Results showed that Er3+ ions entered the Lu3+ sites successfully without causing any obvious peak changes, and the doping concentration of Er3+ had important influence on the Er3+ local structure in Na5Lu9F32 crystals. The maximum emission intensities of ~1.5 and ~2.7 μm were obtained in present research when the doping concentration of Er3+ were 4 and 5 mol%, respectively, under the excitation of 980 nm LD. In these doping concentration, the maximum emission cross-sections were calculated to be 1.37 × 10−20 cm2 (~1.5 μm) and 2.1 × 10−20 cm2 (~2.7 μm). The gain cross-section at 2.7 μm was also estimated according to the absorption and emission cross section spectra. All these spectroscopic characterizations suggested that this fluoride crystal would possess promising applications in infrared lasers.

Anisotropic laser properties of Yb:Ca3La2(BO3)4 disordered crystal

We report Er3+-doping, Mg2+-codoping and crystal composition effects on emission and absorption cross sections of Er3+-only doped and Er3+/Mg2+-codoped LiNbO3 crystals, in which Er3+ concentration ranges from 0.3 to 2.7 mol% and Mg2+ concentration from 1.2 to 7.4 mol%. The emission cross section spectra were calculated from the measured fluorescent spectra and the absorption cross section spectra were computed using the McCumber relation. The results show that increasing Er3+ concentration tends to decrease the cross section, while codoping with Mg2+ or increasing crystal composition tends to increase the cross section. As the composition is close to the stoichiometry, the cross section value tends to a constant. These effects are related to Er3+ site redistribution induced by doping or crystal composition alteration.

Na5Y9F32 single crystals doped with ∼ 0.8-mol% Ho3+, ∼ 1-mol% Tm3+, and various Er3+ ion concentrations were prepared by a modified Bridgman method. The effects of Er3+ ion concentration on 2.0-μm emission excited by an 800-nm laser diode were investigated with the help of their spectroscopic properties. The intensity of 2.0-μm emission reached to maximum when the Er3+ ion concentration was ∼ 1 mol%. The energy transfer mechanisms between Er3+, Ho3+, and Tm3+ ions were identified from the change of the absorption spectra, the emission spectra, and the measured decay curves. The maximum 2.0-μm emission cross section of the Er3+/Ho3+/Tm3+ tri-doped Na5Y9F32 single crystal reached 5.26 × 10−21 cm2. The gain cross section spectra were calculated according to the absorption and emission cross section spectra. The cross section for ∼ 2.0-μm emission became a positive gain once the inversion level of population was reached 30%. The energy transfer efficiency was further increased by 11.81% through the incorporation of Er3+ ion into Ho3+/Tm3+ system estimated from the measured lifetimes of Ho3+/Tm3+- and Er3+/Ho3+/Tm3+-doped Na5Y9F32 single crystals. The present results illustrated that the Er3+/Ho3+/Tm3+ tri-doped Na5Y9F32 single crystals can be used as promising candidate for 2.0-μm laser.

Spectroscopy of Yb-doped tungsten–tellurite glass and assessment of its lasing properties