Optical fuse based on the photorefractive effect for defending the light-injection attacks of quantum key distribution
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Abstract
Light-injection attacks pose critical security threats to quantum key distribution (QKD) systems. Conventional defense methods, such as isolators, filters, and optical power monitoring, are confronted with the threats of specific attacks and the limitations in integration. To address this, we propose and experimentally demonstrate an integrated attack sensing and automatic response unit utilizing the photorefractive effect in a thin-film lithium niobate microring resonator. Our unit provides a high rejection ratio against non-resonant injected light. For resonant attacks exceeding tens of microwatts, the unit can autonomously attenuate the transmission of the quantum signal light, leading to a significant suppression of the secret key rate. This work enhances the security of QKD systems against light-injection attacks by providing a highly sensitive, broadband, and on-chip defense mechanism.