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<p>We investigate third-harmonic generation (THG) in GaAs/AlGaAs semiconductor nanostructures within a non-Markovian density matrix framework that incorporates finite bath correlation time through a time-nonlocal relaxation kernel. This approach extends the conventional Markovian treatment by accounting for temporally structured dissipation in carrier dynamics. The results indicate that finite environmental memory enhances the THG amplitude while preserving the resonance energy structure. Within the explored parameter range, correlation times up to 2 ps yield a reproducible enhancement of approximately 20–25%, with the strongest increase occurring below <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\tau _m \approx 1\)</EquationSource> </InlineEquation> ps. The amplification originates from the gradual buildup of relaxation, which allows phase coherence between intermediate states to persist longer during the formation of third-order polarization. Temporal polarization dynamics confirm that memory primarily modifies decoherence rates rather than energy spacings. In addition, Kramers–Henneberger laser dressing provides approximately independent spectral control, systematically shifting the resonance frequency without substantially altering peak magnitude. The combined influence of laser-induced confinement renormalization and memory-induced dissipative reshaping reveals a dual-control mechanism in which external fields tune spectral position, whereas bath correlation time modulates nonlinear gain. These findings clarify the dynamical role of finite bath memory in semiconductor nonlinear optics and identify environmental correlation time as a physically meaningful parameter for optimizing ultrafast nonlinear response.</p>

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Non-Markovian enhancement of third harmonic generation in GaAs/AlGaAs nanostructures: memory-induced coherence and laser field control

  • 期刊论文

  • 发表日期：

    2026年7月6日

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  • Lakhdar Sek,
  • Abdelmonem Miloudi,
  • Issam Zaiz

摘要

We investigate third-harmonic generation (THG) in GaAs/AlGaAs semiconductor nanostructures within a non-Markovian density matrix framework that incorporates finite bath correlation time through a time-nonlocal relaxation kernel. This approach extends the conventional Markovian treatment by accounting for temporally structured dissipation in carrier dynamics. The results indicate that finite environmental memory enhances the THG amplitude while preserving the resonance energy structure. Within the explored parameter range, correlation times up to 2 ps yield a reproducible enhancement of approximately 20–25%, with the strongest increase occurring below \(\tau _m \approx 1\) ps. The amplification originates from the gradual buildup of relaxation, which allows phase coherence between intermediate states to persist longer during the formation of third-order polarization. Temporal polarization dynamics confirm that memory primarily modifies decoherence rates rather than energy spacings. In addition, Kramers–Henneberger laser dressing provides approximately independent spectral control, systematically shifting the resonance frequency without substantially altering peak magnitude. The combined influence of laser-induced confinement renormalization and memory-induced dissipative reshaping reveals a dual-control mechanism in which external fields tune spectral position, whereas bath correlation time modulates nonlinear gain. These findings clarify the dynamical role of finite bath memory in semiconductor nonlinear optics and identify environmental correlation time as a physically meaningful parameter for optimizing ultrafast nonlinear response.