An Optical Domain Signal Analyzer, having an optical filter, a dispersive element and a detector is utilized to provide high resolution spectrum analysis over a wide optical bandwidth. The optical domain signal analyzer broadly includes an optical filter for providing wavelength samples of a received optical signal, a dispersive element for receiving the samples and dispersing the samples, and a detector for receiving the dispersed signal and for providing electrical signals representative of the dispersed sample. A preferred embodiment includes a processor for receiving the electrical signal and calculating the characteristics of the spectrum.