Abstract: An apparatus for interrogating wavelength-specific devices has a broadband optical source to illuminate an interferometer which provides a low coherence temporal interferogram. At least one array of wavelength-specific devices, such as fiber Bragg gratings connected in series with one another, receives the interferogram, so that each device interacts with a limited range of wavelength bandwidth relative to the bandwidth of the broadband optical source. Instead of illuminating an interferometer with the output of an array of devices which have each interacted with a broadband light source at their own characteristic wavelengths, therefore, an interferometer is used to modulate the output from a broadband source to produce a low coherence interferogram. The array of devices then extracts or filters a higher coherence interferogram from this low coherence interferogram.