Close-Packed Silicon Lens Antennas for Millimeter-Wave MKID Camera

We have been developing a large-format millimeter-wave camera based on lens-antenna-coupled microwave kinetic inductance detectors (MKIDs) for a planned telescope at Dome Fuji (3810 m a.s.l.), Antarctica. Optical coupling to the MKID incorporates double-slot antennas and a silicon lens array. To realize a large-format camera ( > 10,000 pixels), a highly integrated small-diameter lens array and fast optics are required. Lens diameters of 1.2, 2, and 3 times the target wavelength are investigated for the main beam symmetry, side-lobe level, cross-polarization level, and bandwidth, considering the effects of the surrounding lenses. In this study, we present the simulated beam pattern profiles of close-packed lens antenna and the effect of misalignment between the silicon lens and double-slot antenna. We also show the evaluations of the developed 721-pixel close-packed silicon lens array.