Enhancing Entangled Two-Photon Absorption for Picosecond Quantum Spectroscopy

Ryan K. Burdick, George C. Schatz, Theodore Goodson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Entangled two-photon absorption (ETPA) is known to create photoinduced transitions with extremely low light intensity, reducing the risk of phototoxicity compared to classical two-photon absorption. Previous works have predicted the ETPA cross-section, σe, to vary inversely with the product of entanglement time (Te) and entanglement area (Ae), i.e., σe ∼1/AeTe. The decreasing σe with increasing Te has limited ETPA to fs-scale Te, while ETPA applications for ps-scale spectroscopy have been unexplored. However, we show that spectral-spatial coupling, which reduces Ae as the SPDC bandwidth (σf) decreases, plays a significant role in determining σe when Te > ?100 fs. We experimentally measured σe for zinc tetraphenylporphyrin at several σf values. For type-I ETPA, σe increases as σf decreases down to 0.1 ps-1. For type-II SPDC, σe is constant for a wide range of σf. With a theoretical analysis of the data, the maximum type-I σe would occur at σf = 0.1 ps-1 (Te = 10 ps). At this maximum, σe is 1 order of magnitude larger than fs-scale σe and 3 orders of magnitude larger than previous predictions of ps-scale σe. By utilizing this spectral-spatial coupling, narrowband type-I ETPA provides a new opportunity to increase the efficiency of measuring nonlinear optical signals and to control photochemical reactions requiring ps temporal precision.

Original languageEnglish (US)
Pages (from-to)16930-16934
Number of pages5
JournalJournal of the American Chemical Society
Issue number41
StatePublished - Oct 20 2021

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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