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

We fabricate ridge-type optical waveguides by laser direct writing. Lines of Si(3)N(4), typically 10 microm wide and 0.6 microm high, are drawn on Si substrates covered with a 0.5-microm-thick SiO(2) buffer layer. An Ar(+) laser is used to heat the substrate locally and to induce a thermal reaction for SiH(4) and NH(3). The writing speed is up to 1.8 mm/min. The transmission loss for the TE(0) is 0.6 dB/cm.