CPML
Convolutional Perfectly Matched Layer (CPML) is an absorbing boundary condition used in time-domain simulations of wave propagation, most notably in computational electromagnetics. It serves as an improvement over the original perfectly matched layer by providing superior absorption of outgoing waves across a broad range of frequencies and incidence angles, including grazing incidence. CPML achieves this by implementing a stretched-coordinate transformation in time domain, realized through convolution rather than purely frequency-domain operations.
In practical terms, CPML replaces simple damping layers with an anisotropic, lossy boundary region. The method
CPML is widely used with finite-difference time-domain (FDTD) and other time-domain methods and is applicable to
Overall, CPML is a standard technique for simulating open or unbounded domains in wave physics, helping to