SILICON-NITRIDE RIDGE-TYPE OPTICAL WAVE-GUIDES FABRICATED ON OXIDIZED SILICON BY LASER DIRECT WRITING

We fabricate ridge-type optical waveguides by laser direct writing. Lines of Si3N4, typically 10-mu-m wide and 0.6-mu-m high, are drawn on Si substrates covered with a 0.5-mu-m-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.