Abstract
This paper reports the experimental investigation of two different approaches to random bit generation based on the chaotic dynamics of a semiconductor laser with optical feedback. By computing high-order finite differences of the chaotic laser intensity time series, we obtain time series with symmetric statistical distributions that are more conducive to ultrafast random bit generation. The first approach is guided by information-theoretic considerations and could potentially reach random bit generation rates as high as 160 Gb/s by extracting 4 bits per sample. The second approach is based on pragmatic considerations and could lead to rates of 2.2 Tb/s by extracting 55 bits per sample. The randomness of the bit sequences obtained from the two approaches is tested against three standard randomness tests (ENT, Diehard, and NIST tests), as well as by calculating the statistical bias and the serial correlation coefficients on longer sequences of random bits than those used in the standard tests.
Highlights
Semiconductor lasers are very sensitive to perturbations from the outside environment [1, 2]
The output light is fed back into the laser facet after it passes through a fiber ring cavity that consists of an optical circulator (OC), a variable optical attenuator (VA), and a fiber coupler (FC)
The PDF resembles a Gaussian distribution, the asymmetry of the PDF is clearly identified by comparing it with the fitted Gaussian [blue curve in Fig. 2(a)], which is a common feature of chaotic semiconductor lasers
Summary
Semiconductor lasers are very sensitive to perturbations from the outside environment [1, 2]. Many conventional laser-diode systems are commonly prepared with optical isolators to impede feedback from surface reflections. In view of the technological importance of these devices, the rich nonlinear dynamics of semiconductor lasers with delayed feedback/injection have been widely investigated [3, 4]. A form of chaotic dynamics, termed coherence collapse, has been exploited for several applications, such as chaos-based communications [5, 6], chaotic lidar/radar [7], reservoir computing [8], and chaos-based random bit generation (RBG) [9,10,11]. Our focus here is on chaotic laser-diodes for RBG
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