We propose and experimentally demonstrate a novel physical layer encryption scheme for high-speed optical communication. A 10 Gb/s on-off keying signal is secretly transmitted over 100 km standard single-mode fiber. The intensity-modulated message is secured by the encryption mechanism, which is composed of an external noise source and an internal time-delayed feedback loop. The external noise serves as an entropy source with sufficient randomness. The feedback loop structure in the transmitter introduces a time-domain encryption key space, and a corresponding open-loop configuration at the receiver side is used for synchronization and decryption. Experiment results show the effectiveness of the proposed scheme. For a legitimate terminal, bit error rate below 10−8 can be obtained. Decryption degradations with the mismatch of different hardware parameters are researched. The time delay in the feedback loop provides a sensitive encryption key. For other hardware parameters, the system is robust enough for synchronization. Meanwhile, the time-delay signature of the loop is able to be well concealed by the external noise. Moreover, the proposed scheme can support density wavelength division multiplexing transmission with a relatively simple structure. This work also provides a new concept to establish optical secure communication by combining a time-delayed feedback chaotic system and random noise.

中文翻译：

---

具有外部噪声源和内部延时反馈回路的高速光安全通信

我们提出并实验证明了一种用于高速光通信的新型物理层加密方案。10 Gb/s 开关键控信号通过 100 公里标准单模光纤秘密传输。强度调制消息由加密机制保护，加密机制由外部噪声源和内部延时反馈回路组成。外部噪声作为具有足够随机性的熵源。发送端的反馈环结构引入了时域加密密钥空间，接收端采用相应的开环配置进行同步和解密。实验结果表明了所提出方案的有效性。对于合法终端，可以获得低于10-8的误码率。研究了不同硬件参数不匹配导致的解密降级。反馈回路中的时间延迟提供了敏感的加密密钥。对于其他硬件参数，系统足够健壮以进行同步。同时，环路的时延特征能够很好地被外部噪声隐藏。而且，所提出的方案能够以相对简单的结构支持密度波分复用传输。这项工作还提供了一个新的概念，通过结合时滞反馈混沌系统和随机噪声来建立光安全通信。环路的延时特征能够很好地被外部噪声隐藏。而且，所提出的方案能够以相对简单的结构支持密度波分复用传输。这项工作还提供了一种通过将时滞反馈混沌系统和随机噪声相结合来建立光安全通信的新概念。环路的延时特征能够很好地被外部噪声隐藏。而且，所提出的方案能够以相对简单的结构支持密度波分复用传输。这项工作还提供了一种通过将时滞反馈混沌系统和随机噪声相结合来建立光安全通信的新概念。