Femtosecond laser-induced damage on the end surface of double-cladding fluorotellurite fiber

•The damage characteristics and pulse number of fluorotellurite glass fiber end surface under 800 nm and 150 fs laser irradiation were studied for the first time.•Based on the ionization model theory, simulation models for the photon absorption coefficient and the conduction band electron accumulation rate have been established for TBY and ABCYSMT glasses, which to some extent explain the reason for the difference in damage thresholds between the two materials. In this study, the damage characteristics of double-cladding fluorotellurite glass fiber endface was conducted. Double-cladding fluorotellurite fiber was prepared with a core composition of 70TeO2-20BaF2-10Y2O3 (TBY70), an inner cladding composition of 33AlF3-9BaF2-17CaF2-12YF3-8SrF2-11MgF2-10TeO2 (ABCYSMT), and an outer cladding composition of 65TeO2-25BaF2-10Y2O3 (TBY65). It was concluded that at the wavelength of 800 nm, the laser-induced damage threshold (LIDT) of inner and outer cladding were found to be 1951.8 and 1551.8 mJ/cm2, respectively, under single-pulse laser irradiation. Then, the influence of pulse number on the LIDT was studied. As the laser pulse number increased from 1 to 200, the LIDT of outer cladding decreased from 1551.8 mJ/cm2 to 695.2 mJ/cm2 due to the cumulative effect of damage crater defects. When the pulse number reached 100, the LIDT saturated, corresponding to a damage accumulation factor of 0.84. With the pulse number increasing continuously from 50 to 5000, the damage area showed no significant change, but the damage depth increased from 40.4 μm to 73.0 μm. In addition, the damage resistance of the two materials, TBY65 and ABCYSMT, was analyzed based on the ionization rate obtained from simulations.