Singlet oxygen luminescence detection with a fiber-coupled superconducting nanowire single-photon detector

Direct monitoring of singlet oxygen (1O2) luminescence is a particularly challenging infrared photodetection problem. 1O2, an excited state of the oxygen molecule, is a crucial intermediate in many biological processes. We employ a low noise superconducting nanowire single-photon detector to record 1O2 luminescence at 1270 nm wavelength from a model photosensitizer (Rose Bengal) in solution. Narrow band spectral filtering and chemical quenching is used to verify the 1O2 signal, and lifetime evolution with the addition of protein is studied. Furthermore, we demonstrate the detection of 1O2 luminescence through a single optical fiber, a marked advance for dose monitoring in clinical treatments such as photodynamic therapy.