Long-period gratings in planar optical waveguides

摘要: We present a theoretical analysis of light propagation in four-layer planar waveguide that consists long-period grating (LPG) having period the order 100 µm. By means coupled-mode theory, we show such structure is capable coupling from fundamental guided mode to cladding modes at specific wavelengths (resonance wavelengths) and thus results sharp rejection bands transmission spectrum waveguide. Our numerical resonance as well can be significantly changed with parameters. A waveguide-based LPG should provide useful approach design wide range integrated-optic devices, including wavelength-tunable filters, switches, environmental sensors.