Abstract
The linear intensity scaling of entangled two-photon absorption (ETPA) offers a fundamental mechanism to enable nonlinear optical spectroscopy and microscopy under a substantially lower excitation power than is currently feasible. However, the long data acquisition time and low signal-to-noise ratio in reported ETPA-based spectroscopic and microscopic studies prevent its widespread application. To gain the full potential of this novel quantum light approach, it is essential to optimize entangled photon generation for significantly enhanced ETPA responses. Here, we report a new quantum light source by combining entangled photon generation with freespace femtosecond pump-pulse shaping. Through measurements of singles and coincidence counts by varying the patterns applied to a spatial light modulator to control the spectral widths of the pump pulses, we reveal strong dependence of the singles and coincidence count rates as well as their ratios on the spectral widths of pump pulses. An optimal spectral width for the highest ratios between the coincidence photon and the signal or idler photon count rates is also determined. Identification of such optimal spectral widths for entangled photon generation in the presence of postgeneration spectral selection makes this quantum light source a promising choice for ETPA-based spectroscopy and imaging.
| Original language | English |
|---|---|
| Pages (from-to) | 053719-1-053719-8 |
| Journal | Physical Review A |
| Volume | 112 |
| Issue number | 5 |
| DOIs | |
| State | Published - Nov 20 2025 |
Funding
Research was supported by the U.S. Department of Energy, Office of Science, Biological and Environmental Research, Bioimaging Science Program. B.D. was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, Separation Sciences. This work was produced by UT-Battelle LLC under Contract No. AC05-00OR22725 with the U. S. Department of Energy. The publisher acknowledges the U.S. Government license to provide public access under the DOE Public Access Plan [69]. The authors declare no conflicts of interest.