| 摘要: |
| 在星地量子密钥分发领域，信息的安全高效传输是构建天地一体化量子通信网络的核心诉求。为了实现这一目标，提高量子密钥分发中偏振编码的偏振对比度，确保光子偏振态精确产生，成为了亟待攻克的关键课题。研究设计了４种产生45°偏振光的方式，即利用法拉第旋光镜、偏振控制器、保偏光纤转轴熔接、45°保偏光纤偏振分束器产生45°偏振光。分析了不同方式的旋光原理，对系统的旋光角度、偏振消光比、偏振稳定性进行了测试。实验结果表明，保偏光纤转轴熔接的方式偏振性能最优，可稳定产生45.41°的旋光，输出光的偏振消光比达到30 dB 以上，偏振稳定性小于2°，可满足太空中量子密钥分发的设计要求，为星地间安全、高效的量子通信筑牢基础。 |
| 关键词: 量子密钥分发 相位调制偏振编码 45°偏振光 |
| DOI： |
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| 基金项目:中国航天科技集团有限公司自主研发项目 |
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| Research on the Generation Method of 45° Polarized Light for Polarization Coding of Quantum Key Distribution |
| CUI Dou,SUN Xiaojie,LIU Shuang,ZHENG Wei,WANG Xuefeng |
| (1.Beijing Institute of Aerospace Control Devices, Beijing 100039，China; 2.Quantum Engineering Research Center of CASC, Beijing 100094，China;Beijing Institute of Astronautical Systems Engineering, Beijing 100076, China) |
| Abstract: |
| In the field of satellite-to-ground quantum key distribution(QKD), achieving secure and efficient information transmission is the fundamental objective for building an integrated space-ground quantum communication network.To realize this objective, improving the polarization contrast ratio of encoding schemes in QKD and ensuring the precise generation of photon polarization states have emerged as critical challenges.This study proposes four methods to generate 45° polarized light: utilizing a Faraday rotator mirror, a polarization controller, polarization-maintaining (PM) fiber rotational-axis fusion splicing, and a 45° PM fiber polarization beam splitter.The optical rotation mechanisms of these methods were theoretically analyzed, and the systems rotation angle, polarization extinction ratio, and polarization stability were experimentally evaluated.The results demonstrate that the PM fiber rotational-axis fusion splicing method achieves the optimal polarization performance, enabling a stable rotation angle of 45.41°, a polarization extinction ratio exceeding 30 dB, and polarization stability below 2°.These metrics satisfy the design requirements for space-based QKD systems, thereby establishing a robust foundation for secure and efficient quantum communication between satellites and ground stations. |
| Key words: Quantum key distribution Phase modulation polarization coding 45° polarized light |