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Arrayed waveguide grating spectrometers for astronomical applications: new results.
- Source :
-
Optics express [Opt Express] 2017 Jul 24; Vol. 25 (15), pp. 17918-17935. - Publication Year :
- 2017
-
Abstract
- One promising application of photonics to astronomical instrumentation is the miniaturization of near-infrared (NIR) spectrometers for large ground- and space-based astronomical telescopes. Here we present new results from our effort to fabricate arrayed waveguide grating (AWG) spectrometers for astronomical applications entirely in-house. Our latest devices have a peak overall of ∼23%, a spectral resolving power (λ/δλ) of ~1300, and cover the entire H band (1450-1650 nm) for Transverse Electric (TE) polarization. These AWGs use a silica-on-silicon platform with a very thin layer of Si <subscript>3</subscript> N <subscript>4</subscript> as the core of the waveguides. They have a free spectral range of ~10 nm at a of ~1600 about wavelength nm and a contrast ratio or crosstalk of 2% (-17 dB). Various practical aspects of implementing AWGs as astronomical spectrographs are discussed, including the coupling of the light between the fibers and AWGs, high-temperature annealing to improve the throughput of the devices at ~1500 nm, cleaving at the output focal plane of the AWG to provide continuous wavelength coverage, and a novel algorithm to make the devices polarization insensitive over a broad band. These milestones will guide the development of the next generation of AWGs with wider free spectral range and higher resolving power and throughput.
Details
- Language :
- English
- ISSN :
- 1094-4087
- Volume :
- 25
- Issue :
- 15
- Database :
- MEDLINE
- Journal :
- Optics express
- Publication Type :
- Academic Journal
- Accession number :
- 28789281
- Full Text :
- https://doi.org/10.1364/OE.25.017918