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Applied Optics

Enhancement of entropy-source signals from a Brillouin random fiber laser using linear predictive coding decorrelation preprocessing

Jiaxin Yu, Shaofei Wang, Xin Xue, Yi Liu, shuo su, Yicong Shi, Wenjun He, Yajun You, Kewu Li, Jian He, Xiujian Chou

Published Aug 19, 2026• 0 citations
Publisher

Abstract

A decorrelation preprocessing method based on linear predictive coding (LPC) is proposed for enhancing entropy-source signals from a Brillouin random fiber laser (BRFL). Unlike structure-optimization-based approaches, the proposed algorithm directly suppresses predictable components in raw BRFL entropy-source signals by extracting prediction residuals from historical-sample-based linear prediction. Experimental results show that LPC preprocessing significantly reduces the autocorrelation sidelobe ratio of the BRFL sampling sequence from −0.044 to −28.917dB, increases the spectral flatness from 0.005 to 0.952, and improves the amplitude min-entropy from 5.454 to 6.190 bit/sample. After random-bit postprocessing, the generated bitstream exhibits good 0/1 balance and low residual correlation and successfully passes the NIST randomness tests. These results demonstrate the effectiveness of LPC-based decorrelation preprocessing in enhancing BRFL entropy-source signals, indicating its potential for fiber-laser-based physical random number generation and secure information processing.

DOI
10.1364/ao.613749

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True random numbers occupy a core role in the field of encryption and security by virtue of their properties such as unpredictability and independence. In this paper, we propose a high-speed physical random number generator based on a dual-emission random fiber laser. The system improves the spectral bandwidth characteristics of the output signals by adjusting the pump power and the feedback length of the single mode fiber. This study effectively suppresses the autocorrelation feature by performing exclusive-OR operations on the forward and backward random laser signals, and obtain the random number sequence with a generation rate of 20 Gbps by post-processing with high-order finite difference and least significant bit extraction. In order to verify the practical application performance, we apply the random sequence as encryption key to digital image encryption, and the experimental results show that the generator has both theoretical security and practical application value.
A simple novel method for random number generation is presented, based on a random Raman fiber laser. This laser is built in a half-open cavity scheme, closed on one side by a narrow-linewidth 100 mm fiber Bragg grating. The interaction between the randomly excited lasing modes of this laser, in addition to nonlinear effects such as modulation instability, allow the generation of random bits at rates of up to 540 Gbps with minimal post processing. Evaluation of the resulting bit streams' randomness by the NIST statistical test suite highlights the importance of evaluating the physical entropy content, as bit sequences generated by this random laser pass all the statistical tests with a significance level of 0.01, despite being generated at more than twice the theoretical entropy generation speed.
True random bits are crucial for cryptographic systems, particularly in key generation and secure initialization. In this paper, we present a novel technique based on chaotic signals and the addition of pulse-amplitude modulation signals to generate random bits. This technique can be implemented directly in physical systems. The randomness of our generated bit sequences will be examined with the National Institute of Standards and Technology (NIST) statistical test. The results will also be compared with a widely used technique reported in the literature.
Correlations existing between spectral components in multi-wavelength lasers have been the key challenge that hinders these laser sources from being developed to chaotic comb entropy sources for parallel random bit generation. Herein, spectrotemporally uncorrelated multi-order Stokes/anti-Stokes emissions are achieved by cooperatively exploiting nonlinear optical processes including cascaded stimulated Brillouin scattering and quasi-phase-matched four-wave mixing in a Brillouin random fiber laser. Chaotic instabilities induced by random mode resonance are enhanced and disorderly redistributed among different lasing lines through complex nonlinear optical interactions, which comprehensively releases the inherent correlation among multiple Stokes/anti-Stokes emission lines, realizing a chaotic frequency comb with multiple spectrotemporally uncorrelated channels. Parallel fast random bit generation is fulfilled with 31 channels, single-channel bit rate of 35-Gbps and total bit rate of 1.085-Tbps. National Institute of Standards and Technology statistic tests verify the randomness of generated bit streams. This work, in a simple and efficient way, breaks the correlation barrier for utilizing multi-wavelength laser to achieve high-quality spectrotemporally uncorrelated chaotic laser source, opening new avenues for achieving greatly accelerated random bit generation through parallelization and potentially revolutionizing the current architecture of secure communication and high-performance computation.