Controlling the propagation of electromagnetic radiation is described.
A photonic bandgap medium is placed in the path of the electromagnetic radiation,
the photonic bandgap medium comprising a photorefractive material. Control radiation
is projected onto a surface of the photonic bandgap medium. The control radiation
spatially varies a refractive index of the photorefractive material to control
propagation of the electromagnetic radiation through the photonic bandgap medium.