Spectroscopic properties of thulium ions in bismuth silicate glass

Abstract

A new type of bismuth silicate glass (Bi2O3-SiO2-ZnO-Al2O3-La2O3) doped with Tm2O3 is prepared by melt-quenching method. The thermal stability of the glass is examined by differential scanning calorimetry. No crystallization peak is found. Using the absorption and emission spectra, the absorption and emission cross-sections are calculated. In recent years, much attention has been paid to eye-safe ∼2-µm lasers due to their important applications, such as in mid-infrared remote sensing, light detection and ranging, laser medical applications, and pumping parametric oscillators [1−4] . Because strong fluorescence in the broad range from 1.6 to 1.9 µm can be obtained using Tm 3+ as an active ion due to the 3 F 4 → 3 H 6 transition, many types of thulium-doped glasses have been investigated to realize ∼2-µm lasers [3,5−9] . Compared with other glasses, silicate glasses have relatively low thermal expansion coefficients, excellent mechanical characteristics, and high solubility for rare earth ions, which are favorable for optical applications. However, silicate glasses usually have relatively high phonon energy, which leads to harmful nonradiative transition. Bismuthate glasses have low phonon energy [10] and can be easily combined with silicate glasses. Therefore, bismuth silicate glasses may have good physical and chemical properties, similar to normal silicate glasses. To develop more efficient optical devices based on Tm 3+ , the host glass and the concentration of Tm 3+ are two important issues to be considered.In this letter, Bi 2 O 3 -SiO 2 -ZnO-Al 2 O 3 -La 2 O 3 (BSZAL) glass is chosen as host, and the infrared emission properties of Tm 3+ -doped BSZAL glasses with Tm 2 O 3 concentrations ranging from 0.1 mol% to 1.5 mol% are characterized. The curve of differential scanning calorimetry (DSC) and thermal expansion coefficient is plotted to investigate the thermal stability of the glass. Absorption and emission spectra are tested to calculate the absorption and emission cross-sections. In addition, the Judd-Ofelt parameters, spontaneous transition probability, and radiative lifetime of excited levels are calculated from the absorption spectra. The microscopic parameters of the energy transfer process are calculated using the extended overlap integral method. • C for 30 min. Then, the melts are poured on a preheated steel molds and annealed in a furnace near the glass-transition temperature for a minimum of 2 h. All annealed samples are fabricated to a polished plane parallel glass of 1-mm thickness for optical measurements. Bismuth silicate glasses with mol% compositions of 15BiThe refractive index of the host at 1 552 nm is measured by the prism minimum deviation method, whereas the density is measured by the Archimedes water-immersion method in distilled water. The coefficient of thermal expansion is measured using a NETZSCH 402EP with a heating rate of 10

A 2μm continuous wave and passively Q-switched fiber laser in thulium-doped germanate glass fibers

“…Mid-infrared fiber lasers, performing pulsed operation at approximately the 2 μm spectral region, have recently gained considerable attention for several promising applications, including eye-safe lidar, remote sensing in the military and medical surgeries [1][2][3][4]. The broad and smooth gain spectrum of Tm 3+ -doped fiber operating in the 2 μm spectral range (corresponding to 3 F 4 → 3 H 6 transition) make it well-suited for broad wavelength tunability and generation of laser pulses [5].…”