Towards a Single-Photon-Sensitive Fiber for Integrated Radiation Detection

With the rise of nuclear technologies, the need for sensitive, real-time radiation detectors continues to grow. However, current detectors are often limited in their portability, flexibility, and spatial coverage, limiting their use in mobile, distributed, or conformal applications. Here, we describe the development of lightweight, flexible fiber detectors that enable radiation sensing with single-photon resolution. To fabricate these fibers, we investigate hydrodynamic control over a flow-based thermal draw process to integrate silicon photomultiplier microdevices into the core of a scintillating fiber. When radiation is incident on the fiber, the scintillating material generates optical photons, which are waveguided to the in-fiber photodetector. Various fiber materials and architectures are explored to improve optical coupling while maintaining fiber flexibility. Through filtering, amplification, and charge integration techniques, we develop the ability for this fiber to achieve optoelectronic conversion with single photoelectron resolution. Using this all-in-fiber sensing structure, we characterize its responsivity to laser, gamma, and electron sources, demonstrating its potential for conformal radiation detection.