Femtosecond laser micromachining of Si-on-SiO2 for photonic band gap crystal fabrication

Femtosecond laser pulses at 387 run were used to machine Si-on-SiO2 substra tes for photonic band gap crystals. With 387 mil ultrashort near-UV pulses, we obtained holes as small as 160 rim, which is smaller than one half of t he laser wavelength with only conventional optics. Moreover, a pitch size o f 420 nm is also obtained in Si-on-SiO2, which meets the spacing requiremen t for today's telecommunication frequency - 1550 nm. Ultrafast laser microm achining is fast and versatile, thus it is a powerful tool for in-situ micr ostructure operations such as nanostructuring, repairing, and production in dustrial applications.