Arrayed waveguide gratings for astronomical applications

The size and cost of astronomical instrumentation is increasing in proportion to the size of the telescope aperture, becoming unsustainable for the next generation of extremely large telescopes being constructed at present. Hence, there is a great need for miniaturised and more cost effective instrumentation. One potential solution is the integrated photonic spectrograph, using a modified arrayed waveguide grating structure to produce spectrally dispersed light on an integrated chip with physical dimensions much smaller than current spectrographs. Building on previous on-sky demonstrations of a prototype device, we elucidate the modifications necessary to make a commercially-available telecommunications-grade arrayed waveguide grating more favourable for the field of astronomy. The parameters that are discussed include the free-spectralrange, resolution and diffraction order of the device. These parameters will form a foundation for the first generation of arrayed waveguide gratings designed specifically for astronomy.