In this paper, an annular winding structure made of single-mode optical fiber is proposed as the core of a cost-efficient and reliable annular optical fiber temperature sensor (AOFTS). The sensor is mainly due to the multi-mode interference effect to achieve real-time response to external temperature changes. The experimental results show that the average temperature sensitivity of the sensor is about 255.5 pm/°C in the temperature range of − 20 ∘ C − 110 ∘ C ; it has higher sensitivity at low temperatures. At − 20 ∘ C , the sensitivity of the AOFTS reaches 450 pm/°C. The sensor has the advantages of simple fabrication, low fabrication cost, strong stability, and good reproducibility and repeatability. It has great application prospects in the field of low-temperature detection.

We demonstrate the generation of broadband dispersive waves (DWs) and solitons in an 80-cm tellurite microstructured optical fiber (TMOF) designed and fabricated with 78TeO2-5ZnO-12LiCO3-5Bi2O3 (TZLB) glass. A 1810-nm femtosecond laser is used as the pump source with an average pump power ranging from 33 mW to 175 mW, where the tunable frequency range is 211.1 THz, which corresponds to the tunable wavelength range of 1742.9 nm. At 175 mW, the trapped multiple DWs are located at 923.8 nm, 1039.2 nm, 1121.6 nm, and 1204.6 nm and the multiple solitons are located at 2666.7 nm, 2426.1 nm, 2165.9 nm, 1952.7 nm, and 1842.1 nm. The experimentally obtained maximum DW conversion efficiency is 14%, and the maximum soliton conversion efficiency is 43%. The experimental and theoretical results of pulse evolution in the TMOF agree very well. To the best of our knowledge, this is the first time that nine peaks of frequency conversions have been realized simultaneously in non-silicon fibers. The exceptionally high nonlinearity and broadband-tunable characteristics of the proposed TMOF are promising components for the development of compact and highly efficient tunable mid-infrared fiber lasers, wavelength converters, and time-frequency metrology.

A four-hole birefringence tellurite microstructured optical fiber (BTMOF) was designed and fabricated based on 76 .5 T e O 2 − 6 Z n O − 11 . 5 L i 2 O − 6 B i 2 O 3 glass, and its core (slow and fast axes were) measured to be approximately 4.74 µm and 4.29 µm, respectively. The experimentally measured results demonstrated that the maximum supercontinuum (SC) spectra extended from ∼ 914.1 n m to ∼ 1885.1 n m when the polarization state of the pump pulse was parallel to the fast axis at 1400 nm with an average power of 460 mW. We performed numerical simulations based on the nonlinear Schrödinger equation, which support the experimentally measured results. The SC generation in birefringent silica microstructured fiber with the same geometric parameters was simulated, and the results showed that the enhanced nonlinear refractive index of the BTMOF yielded a spectrum with a significantly larger bandwidth. Furthermore, the two polarization states along the fast axis and slow axis exhibit different dispersion characteristics, which provide a convenient way of tuning the properties of the generated SC. This work highlights BTMOF as a promising platform for the development of a SC light source, which can be widely used in food quality inspection, early cancer diagnostics, gas sensing, and high-spatial-resolution imaging.

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