Laser-based frequency-to-pixel mapping method for submillimetre MKID array

ABSTRACT Microwave Kinetic Inductance Detectors (MKIDs) leverage their intrinsic frequency-division multiplexing capabilities to facilitate full-array readout via a single transmission line, thereby offering exceptional scalability for large-format submillimetre (sub-mm) detectors. However, fabrication variations lead to frequency shifts, collisions, and missing resonators, requiring precise frequency mapping for every pixel in these architectures. We present a visible line-laser scanning method that sequentially illuminates array rows and columns with a narrow linear footprint, producing localized quasi-particle generation ($h\nu \gg 2\Delta$) and measurable resonance shifts for direct frequency-to-pixel assignment. As demonstrated by our 157-pixel ROGer polarimeter array, this method accurately establishes the frequency-to-pixel mapping while maintaining the intrinsic MKIDs architecture without necessitating modifications to the focal-plane architecture. This scalable, alignment-friendly approach provides a promising approach to addressing the challenges of large-array MKIDs for next-generation sub-mm instruments.