Cross-dispersion setup for an integrated near-IR astrophotonic spectrograph

Here we present an optical cross-dispersion setup for an astrophotonic spectrograph in the near-IR H-band (1460 to 1630nm). In this spectrograph, the arrayed waveguide grating (AWG) chip acts as the main dispersing element. An AWG produces a 1D spectrum with overlapping spectral orders, and we designed a cross-dispersion setup that can cross-disperse these overlapping spectral orders perpendicular to the 1D spectral output. This setup consists of a collimating lens, a grating, and a focusing lens. The cross-dispersed 2D spectrum is then imaged onto a near-IR detector array. The AWG we used for this project has a spectral resolution of (λ/δλ) of ∼1000 and a free spectral range of 10nm. An on-sky solar test was performed and analyzed, demonstrating the potential of this setup.