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The addition of metallic deoxidizer is effective in reducing oxygen-containing impurities during the preparation of the chalcogenide glass. However, excessive metal can introduce undesirable background scattering in the glass host, and increase the optical fiber loss. In this paper, we propose an effective approach to address this issue by introducing micron-sized filters into a multi-stage dynamic distillation process. Experimental results show that, after removing these particles, the 20-mm-thick As40Se60 glass exhibits a transmittance of 60%, which is close to the theoretical value. Further study reveals a transmittance of up to 60.6% at wavelength of 2.94 μm laser using a G1 glass with low hydroxyl group content. Additionally, an AsSe/GeAsSe fiber with core-size of 200-μm diameter was fabricated via isolated-extrusion method, the fiber exhibits a minimum loss of 0.37 dB/m at 5.7 μm and maintains a low scattering loss of about 0.5 dB/m at the wavelength range from 2.5 to 3.5 μm. The fiber demonstrates an ability of enduring an incident CO2 laser power of 7.2 W and outputting power density of 2.33 ± 0.02 kW/cm2 at a wavelength of 10.6 μm, which is higher than the record of 2.1 kW/cm2 with a water-cooled Ge-As-Se fiber in previous work.

In this work, we report a single-mode Ho3+/Yb3+ codoped fluorotellurite (HYCF) microsphere laser at ∼2.1 μm with low threshold of 96.2 μW. Fluorotellurite glass microspheres exhibit a high Q-factor, reaching up to 106. Furthermore, we demonstrate the thermal tunability of the microsphere lasers, with a temperature sensitivity of 38 pm/°C for the lasing wavelength. These research findings showcase highlight the potential of HYCF glass microsphere lasers as a miniature photonic element in the emerging field of compact IR lasers, low-threshold, as well as for high-precision temperature sensing applications.