Microfabrication of Paul wheel trap chip in fused silica by selective laser etching
We present a rapid, mask-free fabrication workflow for the Paul wheel trap chip based on selective laser etching (SLE) of fused silica. The complete process - femtosecond laser writing, wet-chemical etching in KOH ($\sim$230 $μ$m/h, releasing the trap geometry from a 500 $μ$m wafer in approximately 2 h), RF magnetron sputtering of silver electrodes, and direct femtosecond laser ablation for electrode patterning - is carried out in-house, bypassing photolithographic processing and custom shadow masks entirely. Nine chips per 4-inch wafer can be produced in a single working day, reducing the fabrication lead time by more than one order of magnitude relative to the outsourced CVD diamond design. The functionality of the fabricated wheel trap chip is confirmed by a proof-of-concept microparticle trapping demonstration, in which a single microparticle was confined continuously for 72 h at atmospheric pressure. This establishes SLE of fused silica as a rapid, economically accessible fabrication platform for Paul traps in levitated-optomechanics applications.