Impedance-matching surface plasmon absorber for FDTD siumulation

The perfectly matched layer (PML) is used to be excellent boundary in the finite-difference time-domain method (FDTD), but is failure to absorb surface plasmon (SP) directly. In order to absorbing the incident SP at the end on a metal surface, an impedance-matching layer (IML) is implemented between scattered SP and PML. A very low SP reflection of -28.69 dB is achieved by an IML with length of lambda/3. The IML significantly reduces the reflected SP without significantly increasing the simulation area and creates a quasi-infinite regime for SP propagation.