A numerical approach based on the two-dimensional (2D) Finite Difference Time Domain (FDTD) is employed to design, analyse and optimise the wavelength demultiplexer (WDM) based on photonic crystal waveguide couplers. The performance of the WDM is investigated in terms of device length, optical efficiency and losses. Significant improvement on the power efficiency and the wavelength directionality has been achieved by introducing a single defect on the crossing point between two photonic crystal waveguides.
In this paper, the interactions of pulsed and continuous wave Gaussian beams with a photonic crystal that has a negative effective refractive index are considered. Subwavelength focusing of incident Gaussian beams with a photonic crystal slab due to the negative refraction is discussed theoretically. Negative angle of refraction behaviour associated with the negative index of refraction exhibited by the PC slab is also shown. All our simulations are carried out by using the finite difference time domain (FDTD) method.
We numerically investigate, the unique features of imaging by a superlens made of a photonic crystal slab that possesses the property of negative refraction. We confirm earlier finding that a photonic crystal slab lens can provide the imaging of a point source. We prove that the resolution of such a slab lens can be improved by optimizing the air hole radius as well as the refractive index of the high index material. It is found that by decreasing the radius of the air holes, the spatial resolution is improved significantly. It is also shown that for the case of two sources, the resolution of such a photonic crystal lens can be made indeed better than the radiation wavelength. The finite difference time domain (FDTD) method is used in our numerical simulations.