A major limiting factor of using photonic integrated circuits (PICs) in astronomical instruments is that they are functional only in the single-mode regime. As number of modes M in the PSF scales with diameter D of the telescope (D∕4λ2), it is impractical to use PICs based spectrographs without extreme adaptive optics (exAO) in ground- based observatories. To increase the coupling efficiency of the FoV into a PICs based spectrograph, we can employ a lower order adaptive optics (LOAO) to partially correct the PSFs. The partially corrected FoV is then sampled with an integral field unit (IFU) comprising of micro-lens fed MMF/FMFs, which feed into an array of photonic lanterns (PLs). The multiple SMF outputs of the PLs are butt-coupled across a stack of AWGs, one PL connected to the corresponding AWG or connected across the stack. CAWSMOS is first of its kind concept that exploits the ability of AWGs to spectrally disperse light from more than one fibre simultaneously. Each AWG disperses the wavelengths horizontally, and the cross-disperser disperses the orders vertically. The echellogram from each fibre on an AWG is spatially shifted vertically to occupy the space between the orders. Each AWG is assigned to individual real-estate on the detector area.
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