What is Astrophotonics?
Optical fibres developed for telecommunications have narrow cores and work in single mode. They have been the basis of many exciting new devices built into the fibres. In astronomical applications, where light is scarce, fibres are much thicker to allow more light to pass down the fibre to the detector. As a result, astronomical fibres are usually multimode. Research in astrophotonics aims to develop new applications of photonic devices, originally developed for telecommunications, to important applications in astronomy.
Current research areas
OH-suppression in optical fibres
98% of the sky background in the near infrared J and H bands arises from very narrow OH lines produced in the upper atmosphere. Suppression of these lines promises a huge gain in sensitivity for IR astronomy. Research in recent years has demonstrated the ability to make non-periodic Bragg gratings within an optical fibre. The transmission profile of these fibres can be designed to suppress OH lines with an effective resolution of at least R = 10,000.
Photonic Lantern
In order to use single mode devices in conjunction with multimode fibres, a remarkable new device called a photonic lantern has been developed in which a multimode fibre goes through a taper and splits into a large number of single mode fibres. Quite apart from exciting new uses in astrophysics, there are possible applications in remote sensing and communications.
Integrated Photonic Spectrograph
Astronomical telescopes are getting larger which means that the size and cost of their instruments is also growing rapidly. A radical new approach to this problem is made possible by feeding thousands of optical fibres into thousands of individual miniature spectrographs rather than one huge spectrograph. The first of these devices was manufactured in 2007 and is being tested.
Other Devices
Other prospective astrophotonic devices include the photonic array waveguide grating (AWG) and the photonic echelle grating (PEG).
More Information
For more information contact Joss Bland-Hawthorn