Arrayed waveguide gratings for astronomy with multiple offaxis fibre launch

The next generation of major ground-based optical and near-infrared astronomical telescopes are planned to have aperture sizes from 25–42 meters in diameter, making them substantially larger than existing telescopes. This has a major impact on seeing limited spectroscopic instrumentation, as the size of the instrument grows in proportion to the telescope aperture for traditional designs and more importantly, the cost of the instrument increases with the telescope aperture squared, or faster [1]. This unsustainable trend has necessitated a miniaturization of devices for astronomy, with integrated photonics showing great promise. Particularly of interest is the integrated photonic spectrograph (IPS) [1,2].