PIMMS: Photonic Integrated Multimode Microspectrograph

The PIMMS concept harnesses the photonic lantern, which enables the efficient conversion of an essentially arbitrary input (e.g. a combination of arbitrarily excited modes) to the consistent and diffraction-limited format of single-mode fibres. This essentially allows us to remap the extent of a spectrograph slit, minimising the width while conserving the effective étendue.

There are some key advantages to using a slit form using a phonic lantern:

  1. As the single-mode fibres are by definition diffraction limited, the resulting a spectrograph spectral resolution is also diffraction limited (i.e. the slit width is no longer the limiting factor in the spectrograph resolution equation).
  2. The spectrograph design is decoupled from the light source at the MM input. This is because the beam from a single-mode fibre output of the lantern remains fundamentally unchanged regardless of the source at the MM input.
  3. The conversion also allows other single-mode photonic technologies to be incorporated into new and pre-existing spectrographs, the most successful so far being fibre Bragg gratings for sky OH suppression.

Our PIMMS comes in two flavours. The first, dubbed PIMMS#0 is a hybrid of a classical spectrograph design and photonics This approach uses the photonic lantern to form the slit for a compact bulk optic spectrograph. Our first implementation (seen below) operates over 1545-1555 nm (limited by the detector) with a spectral resolution of 0.055nm (R~30,000) using a 1x7 (1 multi-mode input to 7 single-mode outputs) photonic lantern.

The next generation of PIMMS#0 is an echelle based based design operating in the visible. It is designed to operates over 630-730 nm, with a spectral resolution 10 pm (R~60,000) using a 1x19 (1 multi-mode input to 19 single-mode outputs) photonic lantern.
The second is a fully photonic approach, combining the photonic lantern and an arrayed wave guide grating (spectrograph on a chip).

PIMMS echelle

We present a movie of the instrument’s operation. This is a 91 MB avi file. Another version in QuickTime is available here (124 MB).


PIMMS general

  • Bland-Hawthorn, J., Lawrence, J., Robertson, G., Campbell, S., Pope, B., Betters, C. H., Leon-Saval, S., Birks, T. A., Haynes, R., Cvetojevic, N. and Jovanovic, N.: PIMMS: photonic integrated multimode microspectrograph, Proc. SPIE, 7735, 77350N, doi:10.1117/12.856347, 2010.
  • Robertson, J. G. and Bland-Hawthorn, J.: Compact high-resolution spectrographs for large and extremely large telescopes: using the diffraction limit, vol. 8446, edited by I. S. McLean, S. K. Ramsay, and H. Takami, pp. 844623–844623–13, SPIE. 2012.

PIMMS#0 papers

  • Betters, C. H., Leon-Saval, S. G., Robertson, J. G. and Bland-Hawthorn, J.: Beating the classical limit: A diffraction-limited spectrograph for an arbitrary input beam, Optics Express, 21(22), 26103–26112, doi:10.1364/OE.21.026103, 2013.
  • Betters, C. H., Leon-Saval, S. G., Bland-Hawthorn, J. and Robertson, G.: Demonstration and design of a compact diffraction limited spectrograph, vol. 8446, p. 84463H. 2012.
  • Leon-Saval, S. G., Betters, C. H. and Bland-Hawthorn, J.: The Photonic TIGER: a multicore fiber-fed spectrograph, vol. 8450, p. 84501K. 2012.

PIMMS#1 papers

  • Cvetojevic, N., Jovanovic, N., Betters, C. H., Lawrence, J. S., Ellis, S. C., Robertson, G. and Bland-Hawthorn, J.: First starlight spectrum captured using an integrated photonic micro-spectrograph, Astronomy and Astrophysics, 544, L1, doi:10.1051/0004-6361/201219116, 2012.
  • Cvetojevic, N., Jovanovic, N., Lawrence, J., Withford, M. and Bland-Hawthorn, J.: Developing arrayed waveguide grating spectrographs for multi-object astronomical spectroscopy, Optics Express, 20(3), 2062, doi:10.1364/OE.20.002062, 2012.