Laser-Based Frequency-to-Pixel Mapping Method for Submillimeter MKID Array

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 submillimeter (submm) 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 quasiparticle generation (hν ≫ 2Δ) 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 submm instruments.