Looking for ADI-FDTD sample code

ADI means?
please explain further about ADI.

ADI means Alternating direction implicit.
you can read below para for more information,

The nite-dierence time-domain (FDTD) method is formulated by an explicit
nite-dierence scheme using central dierences on a staggered Cartesian grid
(both in space and time) of Maxwell's equations. It is second-order accurate
both in time and space. It leads to a recursive time-marching algorithm where
the eld values at the current time-step are calculated from the eld values at
the previous time-step.
The time-step size of FDTD method must be small enough so that it satises
the CFL stability condition in. If the time-step size is not within this bound,
the FDTD scheme will become unstable as a FDTD solution marches.
As a result, the FDTD method may require a large number of iterations
in some applications. Consequently, we need an advancement of FDTD tech-
niques that permits accurate and numerically stable operation for values of delta t exceeding the CFL limit. An alternating-direction-implicit (ADI) time-stepping
algorithm is introduced for this purpose.
It is unconditionally stable and, thus, the CFL stability condition can be eliminated.