One of the fundamental assets of KIDs is that they can be easily multiplexed, reading out hundreds of pixels with a single feedline.

While this is true on paper, actually achieving large format arrays, with thousands of good working pixels, remains a challenging task. The GIS collaboration has been working in this direction constantly over more than a decade, passing from the tens or hundreds of pixels per array of the NIKA camera, to 1000 pixels per array in NIKA2 and 2000 in CONCERTO.

This has been possible thanks to the experience gained developing such cameras, coupled to the effort done to get an always better understanding of the key aspects that play a role in the final quality of an array. These include in particular mastering the various fabrication steps that are needed to produce an array, simulating the devices and choosing the designs that can accommodate the largest number of pixels while minimizing the risks of frequency collisions, and optimizing the architecture of the focal plane, to assure an efficient optical coupling, the good thermalization of the arrays and a solid mounting.

Today, we are working on the next generation of large format arrays, called 8KID : one single 4 inches wafer containing more than 8000 pixels, optimized for the mm-wave bands. We have already fabricated and tested the first working samples. Being able to consistently produce high quality 8KID arrays will be a crucial step towards the next generation of experiments, with focal planes requiring tens of thousands of detectors.

Updated on 21 février 2022