Laser discrimination and detection at the sub-pW level using photon sensitive detection of self coherence

Abstract: Wavelength independent detection and discrimination of laser radiation has been performed by detecting the 'self coherence' of an incoming light source with photon sensitive detectors. The system successfully discriminates between coherent and incoherent sources. Detection of scattered light has been performed across the visible spectrum with filters or internal or external source comparisons. The ultimate detection sensitivity was shown to be 0.38pW for a continuous wave HeNe laser at 632nm. We beleive this to be the most sensitive wavelength independent detection of a CW laser ever reported.