We demonstrate the implementation of a fiber-integrated spectrograph utilizing chromatic group velocity dispersion (GVD) in a single-mode fiber. By means of GVD we stretch an ultrafast pulse in time in order to spectrally resolve single photons in the time domain, detected by single-photon counting modules with very accurate temporal resolution. As a result, the spectrum of a very weak pulse is...

Sound spectrographs based on digital computers are of interest because of the versatility they offer in generating and displaying sound spectrograms. A particular computer-based sound spectrograph is described in which digitized time waveforms stored on disk memory are spectrally analyzed and the resulting data stored back on disk for later display. Analyses are also performed to obtain the voi...