Time delay signature suppressed broadband chaotic laser for high-speed all-optical true random number generator

在量子密码系统中，真正的随机数对于科学计算、随机建模、安全通信和量子密钥分发具有重要意义。混沌激光为真正的随机数生成提供了高质量的随机性。在基于混沌的随机数发生器中，混沌激光的带宽决定了产生的比特率，目前混沌激光的比特率限制在35 GHz左右，并且需要大量的后信号处理。在典型的混沌激光系统中，来自外部光反馈的额外竞争动态对于宽带混沌输出是必不可少的。然而，由于产生的光混沌存在时间延迟特征，几乎所有的混沌激光器都不能满足不可预测、不可再现和统计无偏的特征。这是混沌激光产生的基本组成部分，通过固定延迟时间的不同激光注入来产生混沌性质。结果产生的混沌激光输出的时间延迟特征导致了可预测性，使其无法产生随机数。为了克服上述瓶颈，我们提出了一种新的混沌激光发生器，具有良好的带宽扩展和无时延特征。通过对随机周期、随机光反馈强度的外部光注入进行双失谐处理，该混沌激光器的带宽可以很好地扩展到50GHz。特别是，通过我们提出的随机光纤光栅实现随机分布光反馈，以消除时间可预测性并抑制时间延迟特征，这将首次得到证明。所要求的50GHz信号分析仪对于电频域混沌带宽（上限为50GHz）的表征以及时延特征抑制的识别至关重要。提出的混沌激光器将及时建立一个高速真随机比特发生器，使加拿大在该领域具有竞争优势，为实际应用于保密通信铺平了道路。这种基于随机光栅的混沌激光器可用于量子通信、微波光子学源和中性动力学。它为电信和生物医学仪器的学术和行业的许多本地合作以及国际合作打开了大门。

Truly random numbers are important for scientific computation, stochastic modeling, secure communications and quantum key distribution in quantum cryptography systems. Chaotic lasers provide high quality randomness for truly random number generation. In chaos-based random number generator, the bandwidth of the chaotic laser dominates the generated bit rate which is limited around 35 GHz to date and they require significant post-signal processing. In typical chaotic laser system, additional competition dynamic from external optical feedback is essential for a broadband chaotic output. However, the unpredictable, unreproducible and statistically unbiased features cannot be met by almost all of chaotic lasers due to the time delay signature in the generated optical chaos. This is attributed by the basic building block of chaotic laser generation via different laser injection with a fixed delay time to create chaotic nature. As a result, the time delay signature of the generated chaotic laser output induced the predictability, which disqualified them from random number generation. To overcome the above-mentioned bottleneck, we propose a novel chaotic laser generation with a well extended bandwidth as well as free from time delay signature. By dual detuning external light injections with distributed random periods with randomized optical feedback strength, the bandwidth of the proposed chaotic laser would combine the multiple gain spectra and be well extended up to 50GHz. In particular, random distributed optical feedback through our proposed random fiber grating are implemented to remove the temporal predictability and suppress the time delay signature, which will be demonstrated for the first time. The requested 50GHz Signal Analyzer is crucial for the characterization of the chaos bandwidth in electrical frequency domain with the upper limit range of 50 GHz, as well as the identification of the time delay signature suppression. The proposed chaotic laser would build up a high speed true random bit generator timely to give Canada competitive edge in this field, paving a way for practical application in secure communication. This random grating based chaotic laser can be used for quantum communication, microwave photonics source and neutral dynamics. It opens doors for many local collaboration, as well as international collaborations in academic and industry of telecom and biomedical instrumentation.