A double-tapered fibre array for pixel-dense gamma-ray imaging

Luminescence intensity in photodetectors, radiation imagers and light-emitting diodes is proportional to the thickness of the light-emitting layer. However, a thick emitting layer reduces light output because of incoherent photon scattering and attenuation. Here we present the design of double-tapered optical-fibre arrays that can drastically increase the light output of thick light-emitting layers by progressively filling more propagation modes along the fibre's depth. To enhance the light-collection efficiency and imaging resolution, the upper taper angle of each fibre is greater than the lower angle. By filling the fibre substrate with perovskite nanocrystals from a scale of micrometres thick to centimetres thick, large-scale pixel-dense X-ray or gamma-ray detector arrays can be fabricated. We demonstrate X-ray imaging with a spatial resolution of 22 lp mm(-1). Pixelated gamma-ray imaging is also demonstrated using a nanocrystal scintillator film with a thickness of 4 mm and similar to 10,000 pixels under focused 6-MeV irradiation. Dynamic changes in the energy spectrum (5 keV to 10 MeV) and dose rate (3.5 nGy s(-1) to 96 mGy s(-1)) can be conveniently monitored using a hemispherical fibre array dosimeter with a field of view of 150 degrees. This study presents a high-throughput approach for fabricating thick emitter layers that could be applied to biomolecular or mechanical force sensing, medical imaging and ion beam therapy.

Automated summary

This study presents the design of double-tapered optical-fibre arrays to increase the light output of thick light-emitting layers. It demonstrates the fabrication of large-scale pixel-dense X-ray and gamma-ray detector arrays. It also shows the possibility of high-resolution X-ray and gamma-ray imaging, as well as convenient monitoring of dynamic energy spectrum and dose rate using a hemispherical fibre array dosimeter.