Impact of LOCOS techniques on photonic wire waveguides

We use the LOCal oxidation of silicon (LOCOS) method as a fabrication technique to define submicrometer photonic waveguides. We attempted fabricating the wire waveguides with two different masking processes, one with a stack of pad oxide and silicon nitride layers, and the other with a single silicon nitride layer. The smallest waveguide we achieved had a cross-section profile of 280 nm×650 nm. The propagation loss of the waveguides was measured by the cut-back method, and the bending loss was measured by employing the serpentine pattern. The minimum propagation loss achieved was 8.78 dB/cm and the bending loss was 0.0089 dB/90° bend for a 5 μm bending radius.