TY - JOUR
T1 - Enhancing Entangled Two-Photon Absorption for Picosecond Quantum Spectroscopy
AU - Burdick, Ryan K.
AU - Schatz, George C.
AU - Goodson, Theodore
N1 - Funding Information:
This work was based on work supported by the National Science Foundation through Grant CHE-1836374 (TGIII) and by the Air Force Office of Scientific Research (Biophysics) Grant No. FA9550-20-1-0380 (TGIII). G.C.S. was supported by NSF Grant CHE-2055565. We thank Oleg Varnavski, Gyeongwon Kevin Kang, and Kobra A. Nasiri for helpful conversations.
Publisher Copyright:
© 2021 American Chemical Society.
PY - 2021/10/20
Y1 - 2021/10/20
N2 - 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.
AB - 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.
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U2 - 10.1021/jacs.1c09728
DO - 10.1021/jacs.1c09728
M3 - Article
C2 - 34613733
AN - SCOPUS:85117476328
SN - 0002-7863
VL - 143
SP - 16930
EP - 16934
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 41
ER -