Randomness evaluation for an optically injected chaotic semiconductor laser by attractor reconstruction

Abstract

State-space reconstruction is investigated for evaluating the randomness generated by an optically injected semiconductor laser in chaos. The reconstruction of the attractor requires only the emission intensity time series, allowing both experimental and numerical evaluations with good qualitative agreement. The randomness generation is evaluated by the divergence of neighboring states, which is quantified by the time-dependent exponents (TDEs) as well as the associated entropies. Averaged over the entire attractor, the mean TDE is observed to be positive as it increases with the evolution time through chaotic mixing. At a constant laser noise strength, the mean TDE for chaos is observed to be greater than that for periodic dynamics, as attributed to the effect of noise amplification by chaos. After discretization, the Shannon entropies continually generated by the laser for the output bits are estimated in providing a fundamental basis for random bit generation, where a combined output bit rate reaching 200 Gb/s is illustrated using practical tests. Overall, based on the reconstructed states, the TDEs and entropies offer a direct experimental verification of the randomness generated in the chaotic laser.

Atmospheric pressure air microplasma current time series for true random bit generation

“…However, for high-speed real-time encryption applications, RBGs are mostly dependent on off-chip sources of entropy such as chaotic semiconductor lasers [25][26][27][28]44 , optical and non-optical quantum fluctuations 33,45,46 , and others 47 . Photonic devices with high bandwidth are the most popular options, and are able to reach ultra-fast bit rates of tens and hundreds of Gbit/s 27,[48][49][50] but at the cost of further post-processing routines that actually increase artificially the overall throughput (for example by means of higher-order derivatives 50 ). The throughput of our APAMP system-based true RBG is lower than that, but its hardware simplicity and consequently low cost are much less.…”

Chaotic laser voltage: An electronic entropy source

“…More broadly, any application that requires the strong suppression or even absence of time-delay signatures [30], for example, chaos-based physical-layer secure communication [31] and chaotic lidar [32], would likely benefit from this chaotic source. The entropy rate is a crucial parameter that determines the potential and the limits of a chaotic process for RNG [20,33,34]. To gain more insight into the advantages of using V (t) over the commonly used I(t), we carry out a permutation-entropy analysis.…”

Numerical study of noise-induced transitions in nonlinear dynamics of optically injected semiconductor lasers

“…Since the 1980s, a semiconductor laser subject to external optical injection has attracted much research interest due to its potential applications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and profound physics [21][22][23][24][25]. Tuning the power and frequency of the optical injection destabilizes the laser through a period-doubling route to chaos, which has been observed numerically [26] and experimentally [27].…”