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Fluorotellurite microstructured fibers (MFs) based on TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method. Tapered fluorotellurite MFs with varied transition region lengths are prepared by employing an elongation machine. By using a tapered fluorotellurite MF with a transition region length of ∼3.3  cm as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source, broadband supercontinuum generation covering from 470 to 2770 nm is obtained. The effects of the transition region length of the tapered fluorotellurite MF on supercontinuum generation are also investigated. Our results show that tapered fluorotellurite MFs are promising nonlinear media for generating broadband supercontinuum light expanding from visible to mid-infrared spectral region.

Optical modulators hold great promise for nonlinear optical and photonic devices. However, current optical modulators are exclusively based on inorganic saturable absorbers such as semiconductor thin films, 2D materials, and plasmonic nanocrystals. Here, nonlinear optical modulation is demonstrated by designing a series of organic semiconducting polymer dots (Pdots) for passive Q‐switching and mode‐locking lasers in the near‐infrared (NIR) region. Combining density functional theory and judicious polymer design, Pdots with large extinction coefficient and broadband absorption are developed which span the entire spectrum from ultraviolet (UV) to NIR region (300 to 2500 nm). The Pdots exhibit strong saturable absorption (β = −1.2 × 10−3 cm W−1) and optical nonlinearity (Imχ(3) = −8.4 × 10−7 esu), which are of orders higher than other nonlinear optical materials such as carbon‐based materials, plasmonic metal nanoparticle, and semiconductor nanocrystals. The Pdot modulators are integrated into the fiber laser systems, and demonstrate passively mode‐locked lasers at 1036, 1038, 1945, 1950 nm and Q‐switched lasers at wavelengths of 1559 and 1957 nm, highlighting the potential of Pdots for advanced nonlinear optical and photonic applications.