Detection of multiple fluorescent labels using superconducting tunnel junction detectors.

We show that cryogenically cooled, photon counting superconducting tunnel junctions ~STJs! can be used to simultaneously record the optical spectra from multiple biological fluorochromes. Measurements with a single-pixel tantalum STJ with a wavelength resolving power R5l/Dl of about 10 confirm the expected sensitivity advantage with respect to the photomultiplier-based detectors commonly used to record signals from microarrays and other fluorescent biological systems.