Resonant Frequency Adjusting of an MSA via Laser Ablation of the Input Coil

A convenient method to permanently adjust the operating frequency of a microstrip superconducting quantum interference device amplifier (MSA) was investigated. An optical laser cutter was used to ablate the input coil of an MSA, bonded to a printed circuit board (PCB), to increase the MSA's operational frequency. During the ablation process, the MSA did not have to be electrically or physically decoupled from the PCB. Using atomic force microscopy imaging, a cutting parameter of a single laser pulse of 1.8 mJ was found to ablate the 50-nm-thick input coil and 10 nm of the SiO
₂
substrate beneath the input coil. After ablation, the bias current was unchanged and the gain of the MSA was relatively consistent, indicating that the ablation process does not affect the Josephson junctions. The resonant frequency of the input was adjusted from 180 to 270 MHz.