Miniature spectrographs: Characterization of arrayed waveguide gratings for astronomy

We present results from a laboratory characterization of integrated photonic arrayed-waveguide grating chips, which are a modified version of commercial arrayed-waveguide grating multiplexors, for the purposes of creating an integrated photonic spectrograph. Using a robust probing setup we measure the peak total efficiency of the chips to be ∼75%. We measure the spectral resolution full-width half maximum to be 0.22 ± 0.02 nm, (giving R = λ/δλ = 7000 ± 700 at 1500 nm). For our device we find the free-spectral range is ∼60 nm and slightly larger than the full-width half-maximum of the efficiency profile (53 nm). Finally, we briefly discuss the importance of an integrated cross-dispersion component for the new integrated photonic spectrograph prototype.