Recent progress on silica-based planar lightwave circuit technology

Optical wavelength division multiplexing (WDM) networks are being studied with a view to enlarging transmission capacity and improving network flexibility. Silica-based planar lightwave circuits (PLCs) can provide various key practical components for these systems because they are suitable for large-scale integration, can be mass produced and offer long-term stability. This paper reviews recent work on three-types of silica-based PLC device; arrayed-waveguide gratings (AWGs), thermo-optic (TO) switches, and a high-speed optical wavelength selector (OWS) which employs hybrid-integration.