How to Enhance Fluorescence of Mid-infrared Lasers? (Physics)

Mid-infrared (Mid-IR) lasers, operating at around three μm, have attracted growing limelight with their important potential in photonic applications. Therefore, it is extremely crucial to find a reliable method for achieving high power Mid-IR lasers.

According to previous researches, the Dy3+_ doped glasses is one of the most efficient ways for mid-IR fiber laser generation. However, conventional glasses such as fluoride glass, heavy metal oxide glass and glass ceramic are inevitably suffering some intrinsic defects that restrict their further improvement. Are there any solutions to address the difficulties and enhance the fluorescence of Mid-IR lasers?

A research team led by Prof. Dr. WANG Pengfei from the Xi’an Institute of Optics and Precision Mechanics (XIOPM) of the Chinese Academy of Sciences (CAS) proposed a new tellurite oxyfluoride glass for Mid-IR laser (2.86 μm) emission and fluorescence enhancement. The results were published in Journal of Non-crystalline Solids

According to the researchers, the tellurite oxyfluoride glass matrix with a composition of (mol%) 71TeO2-10ZnO-10BaF2-4K2O-3Nb2O5-2TiO2 was prepared using melt-quenching method. Moreover, the thoroughly mixed batch of 20 g was melted in gold crucible with a lid at 890 °C  for five hours and dry oxygen was purged into the furnace with a flow rate of 3 L/min from the temperature ramping till casting of the glass melts.

In order to investigate the physical and thermal properties of the proposed glass, the different concentration of Dy3+ ions was calculated.

The results indicate that when Dy3+ was introduced into matrix glass, the Te4+ ion was partially substituted for the Dy3+ ion that has a smaller ionic radius, which led to a decrease in molar refractivity and refractive index. Eventually, the widths of both valence and conduction bands become large and the band gap gets narrow.

Upon 808 nm laser excitation, intense fluorescence peaks at ~2.86 μm were obtained. Calculation of stimulated transition of DyTF glasses indicated the maximum value of spontaneous emission probability and emission cross-section was 83.23 s-1 and 7.82 × 10-21 cm2, respectively. The tellurite oxyfluoride glass ceramic had great enhancement in 2.86 μm fluorescence intensity (about seven times), longer fluorescence lifetime (126 μs).

The results show that the proposed tellurite oxyfluoride glass can be helpful for exploring high gain Mid-IR laser generation.

Featured image: The TEM micrograph of proposed glass ceramic powder dispersed in methanol. (Image by XIOPM)


Reference: Rui Wan, Pengfei Wang, Shengwu Li, Yuan Ma, 2.86 μm emission and fluorescence enhancement through controlled precipitation of ZnTe nanocrystals in DyF3 doped multicomponent tellurite oxyfluoride glass, Journal of Non-Crystalline Solids, Volume 564, 2021, 120842, ISSN 0022-3093, https://doi.org/10.1016/j.jnoncrysol.2021.120842. (https://www.sciencedirect.com/science/article/pii/S0022309321002015)


Provided by Chinese Academy of Sciences

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