Improved laser processing of lithium niobate

Successful laser processing of lithium niobate has so far only been done with lasers using photon energies well above the band gap energy (3.75 eV=330 nm). We report a highly improved method which enables us to do laser processing using a continuous wave (cw) laser operating at low power densities below the band gap energy of lithium niobate, giving us significantly higher removal rates than previously reported in the literature. Using 351 nm cw laser light (Ar
⁺
), high scan speed (100 mm/s), a spot size of 8 μm and 300 mW of laser power results in removal rates in excess of 10
⁶
μm
³
/s. Combined with the possibility of precise focusing (1 μm) and high positioning accuracy (100 nm) of the laser beam, this opens up several new possibilities: micromachining of small piezoelectric structures, simple etching of grooves for a controlled positioning of optical fibers, or etching of grooves in SAW-devices