Garnet nanoparticles in the long-period grating sensors of gamma radiation

Yttrium aluminum garnet (YAG) is a key photonic material with a broad range of applications, including bulk lasers, scintillators, luminophores, etc. Beyond the traditionally used single crystals and powders, it has expanded into optical fibers. This expansion has enabled the development of new fiber scintillators for distributed high-energy radiation sensors and dosimeters. However, the incorporated garnet nanoparticles dissolve into the host silica matrix, forming a multicomponent glass that exhibits violet luminescence, thereby limiting long-distance transmission due to scattering. To further exploit the properties of these fibers, more sophisticated optical components, such as long-period gratings (LPGs), can be used. We report a gamma-ray sensor based on an LPG inscribed in an optical fiber, prepared by incorporating YAG nanoparticles into a silica glass matrix. We evaluated the LPG's spectral response and performance under gamma irradiation. The observed LPG's sensitivity of 2.8 nm · kGy-1 exceeded the values reported for LPG's written in a standard B-Ge single-mode fiber. Although the recovery of the LPG's properties was limited, it can be used as a one-shot probe of gamma radiation. The proposed concept represents a promising alternative to conventional fiber scintillators and dosimeters.