The waveguide is periodic in the direction of propagation, with period = a * sqrt(3), where a is the photonic crystal lattice constant.
Analysisīefore calculating the bandstructure, we will consider the type of results we expect. This allows us to easily create a narrowband source when we want to selectively excite the fundamental mode only. The dipole cloud object that we use in this simualtion does not set the properties of the dipoles so that we are able to set them directly by modifying the global source properties. We use a different dipole cloud than the one in the Object library. The 100 nm thick Si layer is on a 1 μm thick layer of SiO 2. The holes are filled with SiO 2 and the cladding above the waveguide core is also SiO 2. The waveguide is composed of a rectangular a Si 3N 4 rectangular core (1μm width and 400nm thickness), shown in green, on a 100 nm thick layer of Si with a triangular PC lattice of lattice constant a = 400 nm and hole diameter 260 nm. The waveguide has been drawn up in the simulation file waveguide3D.fsp, and is shown in the figure above. In this example we calculate the bandstructure and mode loss of the waveguide structure described in K. When photonic crystals are used to make waveguides, the calculation of the photonic bandstructure becomes a 1 dimensional problem since the waveguide structure is only periodic in the direction of propagation.
