Flexible Hybrid Glass Fiber with Low Optical Loss for X‐Ray Tracking

Compared with traditional inorganic glass fibers, scintillating fibers based on organic–inorganic hybrid glass (OIHMHs) are rarely reported due to the high optical loss induced by the intricate crystallization issue at room temperature. Here, a hybrid glass, namely (C 25 H 30 P) 2 MnBr 4 glass ( C7 glass) is reported, which is free of crystallization issues. Through an investigation of a series of Mn‐based OIHMH glasses, it is found that the organic cation engineering over carbon‐chain length can effectively modulate the glass‐transition temperature of the glass over a range from 60.2–42.7 °C. The C7 glass with the lowest glass‐transition temperature is chosen as the precursor for fiber pulling, generating a crack‐free fiber with diameters spanning over two orders of magnitude (≈10–2000 µm). The fibers exhibit a low optical attenuation coefficient (α = 1.65 × 10 −3 dB µm −1 ) and a high radioluminescence intensity, which inspired the design of a fiber‐array based detector for X‐ray tracking. This work not only enriches the diversity of glass fiber materials but also provides a viable solution for cosmic ray tracking in a large area.