An optical broadband micro-spectrometer containing an input optical assembly, a group of slab waveguide spatial heterodyne spectrometer (SHS) integrated circuits (ICs), a detection module and a processor for multi-line detection. The input optical assembly applies an input light signal uniformly with respect to brightness and frequency to the apertures of the waveguides and may project a pupil image onto the SHS input face and may be a scanner. Each slab waveguide spatial heterodyne spectrometer (SHS) integrated circuit (IC) contains at least one slab waveguide SHS IC. The detection module bonds directly to the slab waveguide output apertures. Each slab waveguide SHS IC may contain one or more slab waveguide SHS.