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Efficient ultra-broadband low-resolution astrophotonic spectrographs.
- Source :
-
Optics express [Opt Express] 2024 May 06; Vol. 32 (10), pp. 17689-17703. - Publication Year :
- 2024
-
Abstract
- Broadband low-resolution near-infrared spectrographs in a compact form are crucial for ground- and space-based astronomy and other fields of sensing. Astronomical spectroscopy poses stringent requirements including high efficiency, broad band operation (> 300 nm), and in some cases, polarization insensitivity. We present and compare experimental results from the design, fabrication, and characterization of broadband (1200 - 1650 nm) arrayed waveguide grating (AWG) spectrographs built using the two most promising low-loss platforms - Si <subscript>3</subscript> N <subscript>4</subscript> (rectangular waveguides) and doped-SiO <subscript>2</subscript> (square waveguides). These AWGs have a resolving power (λ/Δλ) of ∼200, free spectral range of ∼ 200-350 nm, and a small footprint of ∼ 50-100 mm <superscript>2</superscript> . The peak overall (fiber-chip-fiber) efficiency of the doped-SiO <subscript>2</subscript> AWG was ∼ 79% (1 dB), and it exhibited a negligible polarization-dependent shift compared to the channel spacing. For Si <subscript>3</subscript> N <subscript>4</subscript> AWGs, the peak overall efficiency in TE mode was ∼ 50% (3 dB), and the main loss component was found to be fiber-to-chip coupling losses. These broadband AWGs are key to enabling compact integrations such as multi-object spectrographs or dispersion back-ends for other astrophotonic devices such as photonic lanterns or nulling interferometers.
Details
- Language :
- English
- ISSN :
- 1094-4087
- Volume :
- 32
- Issue :
- 10
- Database :
- MEDLINE
- Journal :
- Optics express
- Publication Type :
- Academic Journal
- Accession number :
- 38858945
- Full Text :
- https://doi.org/10.1364/OE.512305