Modes Excitation by Input Field of Different Positions in Three-Mode Photonic Crystal Waveguides

We investigate modes excitation with input field of different positions in three-mode photonic crystal waveguides. The three-mode photonic crystal waveguides is formed by removing three rows rods in 2D photonic crystals. The input field with different positions can excite different modes due to the field intensity distribution of modes. When the input field locates at the position of the zero field intensity of the waveguide mode, the mode can not be excited. The finite-difference time-domain method is used to obtain the excited field distributions.