Dresden 2026 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 1: Optical Properties I

HL 1.6: Vortrag

Montag, 9. März 2026, 10:45–11:00, POT/0006

Optical Limiting Induced by Excited-State Absorption in Thiophene Oligomers — •Mustapha Driouech, Michele Guerrini, and Caterina Cocchi — Friedrich-Schiller Universität Jena, Institute for Condensed Matter Theory and Optics, 07743 Jena, Germany

Optical limiting (OL) is a nonlinear effect that reduces light transmission at high intensities, providing protection for sensitive optical devices and human eyes. Non-perturbative ab initio methods have proven to be powerful predictive tools for OL [1]. In this work, we investigate the optical absorption spectra of a set of thiophene oligomers under the influence of a broadband, instantaneous electric field [2]. At sufficiently high intensities, absorption peaks that are absent in the linear response emerge below the absorption onset in the linear regime. To elucidate the optical nonlinearities involved, we perform pump-probe simulations and analyze the population dynamics, revealing that these emergent features originate from excited-state absorption in the near-infrared to visible region. Further analysis, taking into account both molecular length and applied laser intensity, demonstrates how these factors influence the nonlinear response. Our results show that this fully ab initio approach can accurately capture and unravel the fundamental processes driving optical nonlinearities in thiophene oligomers.

[1] C. Cocchi, et al., Phys. Rev. Lett. 112, 198303 (2014).

[2] M. Driouech, et al., J. Phys. Chem. Lett 16, 11867 (2025).

Keywords: Real-Time Time-Dependent Density Functional Theory; Thiophene Oligomers; Transient Absorption Spectra; Nonlinear Optics