Sub-micron grating formation in Ta2O5-waveguides by femtosecond UV-laser ablation

Beinhorn F, Ihlemann J, Simon P, et al. Sub-micron grating formation in Ta2O5-waveguides by femtosecond UV-laser ablation. Applied surface science. 1999;138-139:107-110.Sub-micron-period surface gratings on Ta2O5 waveguide layers were produced by ablation with a sub-ps-UV-laser. The structure is generated by projection imaging of a primary transmission grating mask. A grating of 500 nm period with a surface modulation depth of 10 nm on a sample area of about 300 µm × 300 µm can be produced with a single laser pulse of about 100 mJ/cm² at 248 nm. Adjustment of the modulation depth to specific requirements can be accomplished by varying laser fluence or pulse number. The structures can be used as grating couplers