The SKA telescope and the DOME project
The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, with eventually over a square kilometre (one million square metres) of collecting area.
The ASTRON & IBM Center for Exascale Technology is a research center located in Dwingeloo, Drenthe, on the Campus of ASTRON, The Netherlands Institute for Radio Astronomy. At this center ASTRON and IBM jointly carry out fundamental research into technologies needed to develop the SKA radio telescope in the latter half of this decade and the first half of the next decade. The collaboration is funded through the DOME project, supported by grants from the Dutch EL&I Ministry and the Province of Drenthe.
IBM Research – Zurich and Astron are collaborating on the realization of an optical beamformer to evaluate its application in the SKA system.
Optical technologies for the SKA telescope
A radio telescope of the size of SKA cannot be built as a traditional single dish, but must be composed from arrays of thousands to millions of antennas. The signals from these individual antennas are then synchronized and combined such that the whole array, with all antennas operating in unison, acts as a single instrument of unequaled performance.
A large part of the infrastructure budget and operating power of the telescope is expected to be consumed by the optical communication network that transports the signals from the single antennas to central locations for processing. A possible path to reduce this cost is to perform an early step in the data processing chain, “beamforming”, close to the antennas. In this beamforming step, signals from a group of antennas are preprocessed such that the whole group “looks into the same direction”. The signals from all antennas in the group can then be added and sent through a single optical communication link. This significantly reduces the number of long distance communication channels and corresponding infrastructure cost and power consumption.
Integrated optical beamforming
The large bandwidth of astronomical signals and the subsequent optical transmission of the preprocessed signal support the use of an optical implementation of the beamforming step. In the framework of the “DOME” project, an integrated optical beamformer chip was designed and produced using Si-photonics integrated optical technology.
IBM’s optical beamformer chip can bring the optical signals from four antennas into phase and combine them into one optical signal, thus reducing the effort for signal transport and further processing by a factor of 4.
Samples of these chips were packaged, wired up to control electronics and shipped to Astron in The Netherlands to become part of an array antenna demonstrator system with integrated optical beamforming processor.
Fully packaged optical beamformer chip including optical input and output fibers as well as electrical connections to the control circuitry.