PSlab stands for the "Photonic Slab" and is a tool for modelling of optical properties in various photonic structures. It can be used for simulations of as well some simple two-dimensional devices, like good old edge emitting laser, as more complicated ones including photonic band-gap materials or photonic crystal based lasers.
The main properties of PSlab are
The computations are performed with the plane wave admittance method (PWAM) -- a fully vectorial and three-dimensional numerical procedure for solving the Maxwell equations in complicated structures. Contrary to other methods (like FDTD or Method of Lines) PWAM does not require spatial discretization of the computational domain but describes the electromagnetic field as a sum of 2D plane-waves with varying amplitudes along z-axis.