Abstract: Micro-Spec (µ-Spec) is a direct-detection spectrometer which integrates all the components of a diffraction-grating spectrometer onto a ~10-cm2 chip through the use of superconducting microstrip transmission lines on a single-crystal silicon substrate. A second-generation µ-Spec is being designed to operate with a spectral resolution of 512 in the submillimeter (500-1000 µm, 300-600 GHz) wavelength range, a band of interest for several spectroscopic applications in astrophysics. High altitude…