Laser machining of single-mode rib waveguides on germanosilicate slabs

Laser ablation was applied for the first time to define a rib waveguide on silica-based planar waveguides. The strong linear absorption of 157-nm radiation was key for producing smooth walls without surface microcracks or significant debris. The laser-formed rib guides were single-mode at 0.635-mu m wavelength and had optical losses of similar to 4 dB/cm as a result of a similar to 40 nm (rms) surface roughness. Simple refinements to the laser etching procedure and extensions to 1.55-mu m telecommunication wavelengths promise commercially attractive losses (<1 dB/cm) for application in processing optical integrated circuits.