Hong-Ou-Mandel sensing technique streamlined to a single femtosecond laser source

Fluorescence lifetime imaging microscopy is a key technology for biomedical research, as it allows for molecular-level interaction measurements both inside and outside of cells. The Hong-Ou-Mandel effect, commonly used for probing quantum mechanical effects, can be applied to fluorescence imaging to enable studies of extremely short timescales; however this technique is often cost prohibitive.

Zickus et al. simplified the technique of fluorescence lifetime with Hong-Ou-Mandel (FL-HOM) sensing by building a supercontinuum source using a photonic crystal fiber and an inexpensive femtosecond fiber laser, which allowed for having a tunable setup arm. In testing the setup, the researchers noticed the super continuum light had interesting statistical properties. Further testing showed the super continuum source allowed for wavelength tunability, though with that also came a possible decrease in visibility at the unstable edges of the generated spectrum.

“It was exciting to gain a deeper understanding of how different light sources affect FL-HOM visibility and how different aspects of the reference and fluorescence compete when it comes to measurement visibility and ease of use,” said author Vytautas Zickus.

The authors hope their findings will make FL-HOM less expensive and more accessible, as well as provide guidance for those interested in using it. They also believe their findings can be applied to life science and material science research where fluorescence lifetime measurements are needed on picosecond scales.

Continuing their research, the researchers are now applying FL-HOM as a blood viscosity probe to improve disease detection. Since temporal resolution is decoupled from timing jitters in FL-HOM, the method also provides a future pathway towards sub-picosecond measurements.

Source: “The role of photon statistics in fluorescence lifetime sensing with Hong-Ou-Mandel effect,” by Vytautas Zickus, Evita Spalinskaitė, Euan Millar, Povilas Jurkšaitis, Ilya Starshynov, Zigmas Balevičius, and Ashley Lyons, APL Photonics (2026). The article can be accessed at https://doi.org/10.1063/5.0347301 .