Post-packaging frequency tuning of microresonators by pulsed laser deposition

This paper presents a post-packaging tuning process for microresonators by PLD (pulsed laser deposition). The microresonators are first hermetically packaged using a RTP (rapid thermal processing) aluminum-to-silicon nitride bonding process. The resonator mass is then altered by adding materials on the surface of the structure using PLD to achieve the desired resonant frequency. The demonstrated tuning resolution is 0.5% per laser shot with a laser beam spot size of 25 x 25 mum(2) and fluence of 616 mJ cm(2). The laser pulse duration is 6 ns and a 0.35 mum thick gold film is used as the deposition material for comb-drive microresonators resonating at 12.45 kHz.