THE INTEGRATED PHOTONIC SPECTROGRAPH MULTIPLE OFF-AXIS INPUTS AND TELESCOPE RESULTS
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THE INTEGRATED PHOTONIC SPECTROGRAPH MULTIPLE OFF-AXIS INPUTS AND TELESCOPE RESULTS Nick Cvetojevic 1,2 , Nemanja Jovanovic 1,2 , Joss Bland-Hawthorn 3 , Roger Haynes 4 , Mick Withford 5 , and Jon Lawrence 1,2 1. Department of Physics and Astronomy, Macquarie University, NSW, 2109, Australia 2. Australian Astronomical Observatory, NSW, 2122, Australia 3. Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW, 2006, Australia 4.innoFSPEC, Astrophysikalisches Institut Potsdam, Potsdam, 14482, Germany 5.CUDOS, Centre for Ultra-high Bandwidth Devices for Optical Systems, Australia
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THE INTEGRATED PHOTONIC SPECTROGRAPH MULTIPLE OFF-AXIS INPUTS AND TELESCOPE RESULTS Nick Cvetojevic 1,2 , Nemanja Jovanovic 1,2 , Joss Bland-Hawthorn 3 , Roger Haynes 4 , Mick Withford 5 , and Jon Lawrence 1,2 1. Department of Physics and Astronomy, Macquarie University, NSW, 2109, Australia - PowerPoint PPT Presentation
Transcript of THE INTEGRATED PHOTONIC SPECTROGRAPH MULTIPLE OFF-AXIS INPUTS AND TELESCOPE RESULTS
THE INTEGRATED PHOTONIC SPECTROGRAPH
MULTIPLE OFF-AXIS INPUTS AND TELESCOPE RESULTS
Nick Cvetojevic1,2, Nemanja Jovanovic1,2, Joss Bland-Hawthorn3, Roger Haynes4, Mick Withford5, and Jon Lawrence1,2
1. Department of Physics and Astronomy, Macquarie University, NSW, 2109, Australia2. Australian Astronomical Observatory, NSW, 2122, Australia
3. Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW, 2006, Australia4.innoFSPEC, Astrophysikalisches Institut Potsdam, Potsdam, 14482, Germany
5.CUDOS, Centre for Ultra-high Bandwidth Devices for Optical Systems, Australia
The Integrated Photonic Spectrograph
A complete “spectrograph on a chip” for astronomy
Fully integrated photonic platform with no moving parts, no alignment, high stability
Mass-producible and small
Current-Generation Spectrographs
Existing spectrographs for astronomy are very large, full of custom built parts, and very expensive
Component & Spectrograph Size increases with Telescope Diameter
Cost ~ Diameter !2
Bland-Hawthorn & Horton (2006)
http://www.astronomy.com/asy/default.aspx?c=a&id=2863
Non-Monolithic Designs
Why not use a multitude of smaller, cheaper, replaceable spectrographs to do the same thing?
http://www.as.utexas.edu/hetdex/
VIRUS Ideal for fiber-fed multi-object spectroscopy
Identical modules combine to form one large spectrograph
25% of the cost of the monolithic design
Still very large!
The Spectrograph Chip
‣ Silica chip with an lithographically written Arrayed Waveguide Grating structure
‣ Typically used in Telecommunication Networks
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Arrayed Waveguide Grating
Input Free Propagation
Zone
OutputFree Propagation
Zone
Array of Waveguides
Input Fibre
Focal Surface
The Spectrograph Chip
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Photonic Lantern
The Photonic Lantern
1x MMF with N modes
N x SMF
Converts a Multimode fibre into multiple Single Mode fibres for efficient interfacing with a telescope
Photonic Lantern
Arrayed Waveguide Grating
Simultaneous Multi-Fibre Input
By interfacing multiple SMFs to one chip we can increase its observational efficiency and reduce the total amount of chips used
Multiple Off-Axis Fibre Launch
So what happens to the spectral output when inputting multiple fibres?
Waveguide Array
Free Prop. Zone
1550 nm
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Top View Front View
Red
BlueFibre #1
Fibre #2
Fibre #3
We would assume that if the fibres are offset enough for the FSR not to overlap we could get separate spectra on the output
Unfortunately this is not the case!
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Top View Front View
Red
Blue
Fibre #1
Fibre #2
Fibre #3
This causes the spectra to be superimposed regardless of the fibre input position
However, if we use a cross-disperser we can uncouple the spectra from the different fibres
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Front View
Red
Blue
Fibre #1
Fibre #2
Fibre #3
If cross-dispersed, we can simultaneously record the spectra from multiple fibres. We can fit as many as the gap between the orders allows.
CrossDispersed
Red
Blue
Red Blue
Higher Orders
Fibre #1
Fibre #2Fibre #3
12-14 Fibres at 125 um spacing
The AAT
Multimode Fibres
The Demonstrator InstrumentLenslet Array
12x SMFPhotonic Lantern
The initial IPS setup
The initial IPS setup
Laser @ 1550nm
The initial IPS setup
Setup #1 – Wide wavelength window, Medium resolution• R ~5000, full H-Band, 12 SMF, 1 MMF
Setup #2 – Highest resolution, Small wavelength coverage.• R ~7000, 50nm wide band, 14 SMF, 1 MMF
Setup #3 – 2 Chips on one detector, Anamorphic optics • R ~2000, full H-Band, 24 SMF, 2 MMF
The Boss supervising
The IPS going on the AAT
The initial IPS setup
Unfortunately, initial tests showed we were not getting enough light through and approaching the noise floor of our detector.
Our detector was not sensitive enough
We decided to use IRIS2, and MacGyvered together a new interface between the IPS and IRIS2
The Raw Results
Antares
1450 nm 1780 nm
Different Orders
Spectra from individual Fibres
The Raw Results
alf Ara (Be Star)
V* Pi 01 Gru (Cold red giant)
Conclusion
We have demonstrated simultaneous input of multiple single mode fibres directly into an AWG chip is possible and practical for Astronomy
If used, cross dispersion is all but essential
We have successfully demonstrated the first IPS-like device on a telescope, with spectra taken from 3 different types of stars.
Currently, redesigning the AWG chips to improve FSR, R, Wavelength Looking at using AO systems to directly couple into SMF
THANK YOU
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