Photonic spatial reformatting of stellar light for diffraction-limited spectroscopy

Harris, R.J.; MacLachlan, D.G.; Choudhury, D.; Morris, T.J.; Gendron, E.; Basden, A.G.; Brown, G.; Allington-Smith, J.R.; Thomson, R.R.

Abstract

The spectral resolution of a dispersive spectrograph is dependent on the width of the entrance slit. This means that astronomical spectrographs trade-off throughput with spectral resolving power. Recently, optical guided-wave transitions known as photonic lanterns have been proposed to circumvent this trade-off, by enabling the efficient reformatting of multimode light into a pseudo-slit which is highly multimode in one axis, but diffraction-limited in the other. Here, we demonstrate the successful reformatting of a telescope point spread function into such a slit using a three-dimensional integrated optical waveguide device, which we name the photonic dicer. Using the CANARY adaptive optics (AO) demonstrator on the William Herschel Telescope, and light centred at 1530 nm with a 160 nm full width at half-maximum, the device shows a transmission of between 10 and 20 per cent depending upon the type of AO correction applied. Most of the loss is due to the overfilling of the input aperture in poor and moderate seeing. Taking this into account, the photonic device itself has a transmission of 57 ± 4 per cent. We show how a fully-optimized device can be used with AO to provide efficient spectroscopy at high spectral resolution.

Citation

Harris, R., MacLachlan, D., Choudhury, D., Morris, T., Gendron, E., Basden, A., …Thomson, R. (2015). Photonic spatial reformatting of stellar light for diffraction-limited spectroscopy. Monthly Notices of the Royal Astronomical Society, 450(1), 428-434. https://doi.org/10.1093/mnras/stv410

• Journal Article Type: Article
• Acceptance Date: Feb 20, 2015
• Online Publication Date: Apr 16, 2015
• Publication Date: Jun 11, 2015
• Deposit Date: Nov 29, 2016
• Publicly Available Date: Dec 14, 2016
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 450
• Issue: 1
• Pages: 428-434
• DOI: https://doi.org/10.1093/mnras/stv410
• Public URL: https://durham-repository.worktribe.com/output/1392062
• Related Public URLs: http://arxiv.org/pdf/1402.2547