Nick Cvetojevic, Nemanja Jovanovic, Jon Lawrence, Michael Withford, Joss Bland-Hawthorn
With the aim of utilizing arrayed waveguide gratings for multi-object
spectroscopy in the field of astronomy, we outline several ways in which
standard telecommunications grade chips should be modified. In particular, by
removing the parabolic-horn taper or multimode interference coupler, and
injecting with an optical fiber directly, the resolving power was increased
threefold from 2400 \pm 200 (spectral resolution of 0.63 \pm 0.2 nm) to 7000
\pm 700 (0.22 \pm 0.02 nm) while attaining a throughput of 77 \pm 5%. More
importantly, the removal of the taper enabled simultaneous off-axis injection
from multiple fibers, significantly increasing the number of spectra that can
be obtained at once (i.e. the observing efficiency). Here we report that ~ 12
fibers can be injected simultaneously within the free spectral range of our
device, with a 20% reduction in resolving power for fibers placed at 0.8 mm off
centre.
View original:
http://arxiv.org/abs/1201.4616
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