Ruijie Cao

2 μm emission properties and nonresonant energy transfer of Er 3+ and Ho 3+ codoped silicate glasses

2.0 μm emission properties of Er3+/Ho3+ codoped silicate glasses were investigated pumped by 980 nm LD. Absorption spectra were determined. Intense mid-infrared emissions near 2 μm are observed. The spectral components of the 2 μm fluorescence band were analyzed and an equivalent model of four-level system was proposed to describe broadband 2 μm emission. Low OH− absorption coefficient (0.23 cm−1), high fluorescence lifetime (2.95 ms) and large emission cross section (5.61 × 10−21 cm2) corresponding to Ho3+: 5I7→5I8 transition were obtained from the prepared glass. Additionally, energy transfer efficiency from the Er3+: 4I13/2 to the Ho3+: 5I7 level can reach as high as 85.9% at 0.75 mol% Ho2O3 doping concentration. Energy transfer microscopic parameters (CDA) via the host-assisted spectral overlap function were also calculated to elucidate the observed 2 μm emissions in detail. Moreover, the rate equation model between Er3+ and Ho3+ ions was developed to elucidate 2 μm fluorescence behaviors with the change of Ho3+ concentration. All results reveal that Er3+/Ho3+ codoped silicate glass is a promising material for improving the Ho3+ 2.0 μm fiber laser performance.

Ho 3+ /Yb 3+ codoped silicate glasses for 2 μm emission performances

This paper discuss a series of Ho³⁺/Yb³⁺ codoped silicate glasses prepared by the melting method. 2 μm emissions of the samples are observed under the pump of 980 nm LD. The Judd-Ofelt parameters (Ω(λ)) and radiative properties are calculated and analyzed; the spontaneous transition probability can reach 78.71  s⁻¹. From the fluorescence spectra, the peak absorption and emission cross section of Ho³⁺ are 2.36×10⁻²¹ and 5.05×10⁻²¹ cm², respectively. In addition, we analyze the energy transfer process of Yb³⁺:  ²F(5/2) level to Ho³⁺:  ⁵I₆ level. Considering the luminance properties and good thermal property, we indicate that Ho³⁺/Yb³⁺ codoped silicate glass is a potential laser glass for the efficient 2 μm laser.

Spectroscopy of thulium and holmium co-doped silicate glasses

In this study, the spectroscopic properties of Tm3+/Ho3+ co-doped silicate glasses under an 808 nm diode laser excitation are reported to discover their potential laser performance. To confirm the best candidates for glass fiber drawing, the optimal ratio of Tm3+ and Ho3+ is 1: 0.3. We calculate and discuss the J-O parameters (Ωt), the transition probability (A) of the transition from 5I7 to 5I8 is 129.89s−1 and the calculated lifetime (τrad) is 7.70 ms, respectively. The maximum emission cross section of the transition from Ho: 5I7→5I8 is 7.59 × 10−21 cm2 at 2065 nm as well as the gain coefficient of the STH glasses is discussed. The energy transfer between Tm3+ and Ho3+ plays an important role in the luminescence process. The sample doped with 1 mol% Tm2O3 and 0.3 mol% Ho2O3 presents a broad band spectrum with a full width at half-maximum of 189 nm, the transfer efficiency from Tm3+ to Ho3+ is 0.6702. Energy transfer constant is 63.2 × 10−40 cm6 /s and the measured fluorescence lifetimes of the sample is 0.637 ms, and the ΔT is 167 °C.These values indicate that the Tm3+/Ho3+ co-doped silicate is a promising way to achieve 2 μm laser emissions.