Silicon nitride ridge-type optical waveguides fabricated on oxidized silicon by laser direct writing

Abstract
We fabricate ridge-type optical waveguides by laser direct writing. Lines of Si3N4, typically 10 μm wide and 0.6 μm high, are drawn on Si substrates covered with a 0.5-μm-thick SiO2 buffer layer. An Ar+ laser is used to heat the substrate locally and to induce a thermal reaction for SiH4 and NH3. The writing speed is up to 1.8 mm/min. The transmission loss for the TE0 is 0.6 dB/cm.