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• The size of the damage crater in wide-bandgap glass ZBLAN is almost constant. • The selection of the damage crater area has a significant impact on the calculation results of the laser-induced damage threshold. • The laser-induced damage threshold of optical materials can be calculated more accurately through the method of laser direct writing. In this paper, we report a comparative study of the laser damage properties of three different systems for infrared glasses (As 2 S 3 , 70TeO 2 -15ZnO-5La 2 O 3 -10WO 3 (TZLW), and 53ZrF 4 -20BaF 2 -4LaF 3 -3AlF 3 -20NaF (ZBLAN)). The effects of laser pulse power and pulse number on glasses damage crater morphology and damage characteristics were systematically investigated under 800 nm femtosecond laser irradiation. According to the Tauc formula, the bandgap values for As 2 S 3 , TZLW, and ZBLAN glasses are 2.01, 2.70, and 4.98 eV respectively. Under femtosecond laser irradiation, a serious edge collapse is found at the edge of the damage crater for the wide-bandgap ZBLAN glass because the high laser energy density affects the accurate calculation of the laser-induced damage threshold (LIDT). According to the characteristics of ZBLAN, glass damage crater size is not sensitive to the pulse numbers. We proposed employing laser direct writing strip damage and using the linear regression method to accurately calculate the damage threshold. The work provides scientific guidance for accurately obtaining the LIDT of optical glass. [ABSTRACT FROM AUTHOR]

• Surface plasmon resonance sensor based on tellurite fiber is realized for the first time. • S-shaped sensing structure with all-fiber integration ensures the stability and mechanical strength of the sensor. • Proposed sensor has high sensitivity and wide temperature detection range. In this paper, an all-fiber S-shaped structure optical fiber surface plasmon resonance (SPR) sensor is proposed for temperature and refractive index measurement. The sensor is made of a single-mode tellurite optical fiber (TOF), and the middle part of the single-mode TOF is heated by a ceramic heating rod to form an S-shaped sensing region, and a 50 nm gold film is deposited in the S-shape sensing area to excite SPR. Based on the excellent properties of tellurite optical fiber, the prepared optical fiber sensor can be used for high sensitivity temperature and refractive index detection. The highest refractive index sensitivity is up to 1068.59 nm/RIU in the range of 1.333–1.380, and the temperature sensitivity is up to −0.713 nm/°C in the range of 30–150 °C. The proposed sensor is simple to fabricate, low-cost, and compact, and can be widely used in biochemical analysis, complex environmental temperature monitoring and other fields. [ABSTRACT FROM AUTHOR]

• Multi-mode fiber Bragg grating was fabricated which can generate several reflection peaks for multi-parameter detection. • With a simple Multi-mode fiber Bragg grating, both temperature and torsion, as well as strain and torsion can be simultaneously detected. • This approach simplifies parameter characterization compared to traditional methods, reducing signal interference and enhancing the clarity of experimental results. In this study, a fiber Bragg grating sensor utilizing multi-mode optical fiber (MM-FBG) is proposed. This sensor can simultaneously detect both temperature and torsion, or strain and torsion. Unlike single-mode fiber, the multiple modes of multi-mode fiber can generate several reflection peaks within the FBG area, increasing data capacity and enabling multi-parameter detection. By monitoring the center wavelength and reflection intensity of the MM-FBG reflection peaks, the sensor can detect temperature, torsion, and strain simultaneously. This approach simplifies parameter characterization compared to traditional methods, reducing signal interference and enhancing the clarity of experimental results. Experimental findings demonstrate that the MM-FBG sensor structure exhibits maximum sensitivities of 0.571 dBm/°/cm for torsion, 12 pm/°C for temperature, and 0.7411 pm/με for strain. Therefore, the fiber sensor proposed in this study shows great potential for monitoring bridge and tunnel structures and for civil engineering applications. [ABSTRACT FROM AUTHOR]