Broadband cloaking and holography with exact boundary conditions.

Broadband cloaking and holography are achieved by creating an exact boundary condition on a surface enclosing an object or free space. A time-recursive, discrete version of the Kirchhoff-Helmholtz integral predicts the wavefield impinging on the surface, as well as its transmission through an arbitrary embedding or replacement medium. Surface source distributions proportional to the predicted wavefield cancel the incident waves and radiate the desired response. The fields inside and outside the surface can be controlled independently. A two-dimensional numerical example shows that cloaking and holography can be achieved to within numerical precision across the frequency range of the incident radiation.