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The Discrete-Time Fourier Series (DTFS) is a fundamental concept in signal processing, serving as the discrete-time counterpart to the continuous-time Fourier series. It allows for the representation and analysis of discrete-time periodic signals in terms of their frequency components. Unlike its continuous counterpart, which utilizes integrals, the calculation of DTFS expansion coefficients involves summations due to the discrete nature of the signal.
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Chaotic Time-Delay Signature Suppression and Entropy Growth Enhancement Using Frequency-Band Extractor.

Yanqiang Guo1,2, Tong Liu1, Tong Zhao1

  • 1Key Laboratory of Advanced Transducers and Intelligent Control System, Ministry of Education, College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China.

Entropy (Basel, Switzerland)
|April 30, 2021
PubMed
Summary
This summary is machine-generated.

This study suppresses time-delay signature (TDS) and enhances entropy growth in chaotic lasers using frequency-band extraction. Optimal bandwidth significantly reduces TDS and boosts randomness, crucial for secure communications.

Keywords:
chaosentropy growthfrequency-band extractorsemiconductor laserstime delay signature

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Area of Science:

  • Optoelectronics
  • Nonlinear Dynamics
  • Information Theory

Background:

  • Chaotic optical-feedback semiconductor lasers exhibit time-delay signatures (TDS) and entropy growth.
  • These properties are critical for applications like secure communication and random number generation.
  • Understanding and controlling these dynamics is essential for optimizing laser performance.

Purpose of the Study:

  • To investigate the suppression of TDS and enhancement of entropy growth in a chaotic semiconductor laser.
  • To analyze the impact of frequency-band extraction on laser dynamics.
  • To explore the potential of this technique for generating randomness.

Main Methods:

  • Experimental and theoretical investigation of a chaotic optical-feedback semiconductor laser.
  • Frequency-band extraction technique applied to laser output.
  • Quantification of TDS using autocorrelation function peak value.
  • Measurement of entropy growth using permutation entropy difference.
  • Analysis of laser intensity distribution skewness.

Main Results:

  • Optimal frequency-band extraction achieved up to 96% suppression of TDS.
  • Entropy growth exceeded the noise-dominated threshold, indicating enhanced randomness.
  • Laser intensity distribution skewness improved to 0.001 at optimal bandwidth.
  • Experimental and theoretical results showed good agreement.
  • Effects of extracting bandwidth and radio frequencies were clarified.

Conclusions:

  • Frequency-band extraction is an effective method for TDS suppression and entropy growth enhancement.
  • This technique offers a promising approach for preparing desired entropy sources.
  • The findings are relevant for chaotic secure communication and random number generation.