Tunable terahertz Bloch oscillations in chirped photonic crystals

We report simulations showing tunable terahertz oscillations of the electromagnetic field provided by the Bloch oscillations of a short photonic wave packet in a tilted band structure. The structure consists in a finite one-dimensional photonic crystal inhomogeneously chirped by a slowly-varying refractive index gradient. Tunability is obtained by relocating the Bloch oscillations center in regions characterized by different local band structure gradients. With reasonable refractive indexes, this mechanism may allow the generation of signals which cover a wide continuous part of the electromagnetic terahertz range, when used in combination of appropriate detection schemes.