We experimentally demonstrate a power limiter based on single-walled carbon nanotubes dispersed in a polymer matrix. This simple fiber-optic device permanently increases its attenuation when subjected to 50-mW or higher cw illumination at 1550 nm and initiates a fiber-fuse effect at 1 to 5 W. It may be used for protecting quantum key distribution equipment from light-injection attacks. We demonstrate its compatibility with phase- and polarisation-encoding quantum key distribution systems.
@article{arxiv.2510.09301,
title = {Fiber-optic power limiter device based on carbon nanotubes},
author = {Ekaterina Borisova and Anastasiya Ponosova and Natalia Arutyunyan and Alexey Shilko and Elena Obraztsova and Boris Galagan and Vadim Makarov},
journal= {arXiv preprint arXiv:2510.09301},
year = {2025}
}