| The ASTRON technical laboratory plays a leading role in the global R&D of technology for aperture arrays and focal-plane arrays for radio astronomy. At this moment, the receptor tiles used in major projects like Embrace and Apertif (both related to SKA) are still entirely electronic, but photonic technology is also being explored. The latter is very attractive for application in future radio astronomy systems because of its excellent broadband and high-frequency properties and also its RFI immunity, low weight and small space envelope.
The picture shows our first photonic demonstrator tile, which was constructed and characterised last year. By equipping this tile with optical analog links and an integrated photonic beamformer, broadband signal reception and broadband, true time delay beamforming between 0.5 GHz and 1.5 GHz was realised and demonstrated.
While optical technology holds great promise, it also presents its own challenges. In this first demonstrator tile we had to deal with pronounced optical phase instabilities in the signal paths (i.e. fibers). This was overcome by careful and clever measuring by Klaas Dijkstra. By increasing the integration level in the next generation photonic tile, only well-controlled on-chip optical signal paths will be present in the system. As a result, optical phase instabilities will not occur. In addition, a wider and higher frequency band from 2 GHz to 5 GHz will be used.
The photonic technology R&D for this first tile and the next generation photonic tile takes place in the Innovation Subsidy-BPB, the SmartMix-MEMPHIS and the PointOne-SATRAX projects, in collaboration with groups at all Dutch technical universities, TNO and Lionix BV.