Abstract :
The paper studies boundary conditions in transformation-optics cloaking for two and three dimensional electromagnetic waves. Implicit boundary conditions for these two cases are derived, no matter if the source is placed in the interior or exterior of the cloak layer. More importantly, the two implicit boundary conditions are derived without solving Mie scattering problems, and these conditions are characteristics of the clock-air interface. In particular, the implicit boundary condition for two-dimensional electromagnetic wave case is reported for the first time. In addition, a sensor can be cloaked in two-dimensional electromagnetic waves, i.e., waves can penetrate into the interior of the cloak layer without exterior scattering.