Ultra-narrow bandwidth filter in fractal photonic crystal containing negative material

In this paper, the self-similarity behavior and the ultra-narrow bandwidth filter character are demonstrated theoretically based on a new one-dimensional fractal photonic crystal containing negative material. There are transmission peaks in the photonic band gap, which show the self-similarity splitting behavior, and the ultra-narrow bandwidth filtering property in the infrared communication band. The width of the transmission peaks become smaller exponentially as fractal level increasing, and it can be less than 0.00001 nm at the infrared 1550 nm when the fractal level more than four. This filtering property is more superior to other kind narrow band filters, and this fractal photonic crystal filter may have many applications in optical communications, such as Dense Wavelength Division Multiplex.