High-efficiency generation of harmonics in polythiophene

N. T. Vasenin, A. V. Ivanenko, V. M. Klement'ev, L. V. Kulik, D. A. Nevostruev, B. N. Nyushkov, S. I. Trashkeev, M. N. Khomyakov

Research output: Contribution to journalArticlepeer-review

Abstract

High-efficiency harmonic generation is observed in a semiconducting polymer RR-P3HT [regioregular poly(3-hexylthiophene)], which exhibits a high nonlinear susceptibility [χ (2) > 10-6 m V-1] under pumping by a pulsed fibre laser. The harmonic generation efficiency in RR-P3HT is comparable or higher than that observed for liquid crystals, which are used in reference experiments to estimate the susceptibility [the quadratic susceptibility of a nematic liquid crystal NLC 1289 is χ (2) ≈ 2 × 10-6 m V-1]. No generation is observed in polythiophene with a random structure, RRa-P3HT [regiorandom poly(3-hexylthiophene)], at the same pump power. It is experimentally demonstrated that a necessary condition for generating the second and third harmonics in a polymer, along with a high pump power density, is the presence of a large power density gradient (exceeding 1013 W m-3). Based on a preliminary theoretical analysis, we can suggest that the quadrupole mechanism, which is a consequence of the regularity of RR-P3HT structure in the thin near-wall layer, may contribute significantly to the nonlinear radiation conversion in semiconducting polymers.

Original languageEnglish
Pages (from-to)437-445
Number of pages9
JournalQuantum Electronics
Volume51
Issue number5
DOIs
Publication statusPublished - May 2021

OECD FOS+WOS

  • 2.02 ELECTRICAL ENG, ELECTRONIC ENG
  • 2.05 MATERIALS ENGINEERING
  • 1.03 PHYSICAL SCIENCES AND ASTRONOMY
  • 1.03.UB PHYSICS, APPLIED

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