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Proceedings Paper

Development of high-resolution arrayed waveguide grating spectrometers for astronomical applications: first results
Author(s): Pradip Gatkine; Sylvain Veilleux; Yiwen Hu; Tiecheng Zhu; Yang Meng; Joss Bland-Hawthorn; Mario Dagenais
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Paper Abstract

Astrophotonics is the next-generation approach that provides the means to miniaturize near-infrared (NIR) spectrometers for upcoming large telescopes and make them more robust and inexpensive. The target requirements for our spectrograph are: a resolving power of 3000, wide spectral range (J and H bands), free spectral range of about 30 nm, high on-chip throughput of about 80% (-1dB) and low crosstalk (high contrast ratio) between adjacent on-chip wavelength channels of less than 1% (-20 dB). A promising photonic technology to achieve these requirements is Arrayed Waveguide Gratings (AWGs). We have developed our first generation of AWG devices using a silica-on-silicon substrate with a very thin layer of Si3N4 in the core of our waveguides. The waveguide bending losses are minimized by optimizing the geometry of the waveguides. Our first generation of AWG devices are designed for H band have a resolving power of ~1500 and free spectral range of ~10 nm around a central wavelength of 1600 nm. The devices have a footprint of only 12 mm × 6 mm. They are broadband (1450-1650 nm), have a peak on-chip throughput of about 80% (~-1 dB) and contrast ratio of about 1.5% (-18 dB). These results confirm the robustness of our design, fabrication and simulation methods. Currently, the devices are designed for Transverse Electric (TE) polarization and all the results are for TE mode. We are developing separate J- and H-band AWGs with higher resolving power, higher throughput and lower crosstalk over a wider free spectral range to make them better suited for astronomical applications.

Paper Details

Date Published: 22 July 2016
PDF: 12 pages
Proc. SPIE 9912, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II, 991271 (22 July 2016); doi: 10.1117/12.2231873
Show Author Affiliations
Pradip Gatkine, Univ. of Maryland, College Park (United States)
Sylvain Veilleux, Univ. of Maryland, College Park (United States)
Yiwen Hu, Univ. of Maryland, College Park (United States)
Tiecheng Zhu, Univ. of Maryland, College Park (United States)
Yang Meng, Univ. of Maryland, College Park (United States)
Joss Bland-Hawthorn, The Univ. of Sydney (Australia)
Mario Dagenais, Univ. of Maryland, College Park (United States)


Published in SPIE Proceedings Vol. 9912:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II
Ramón Navarro; James H. Burge, Editor(s)

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