ИСТИНА

Propagation of light in photonic crystals (PC) is similar to the propagation of X-ray radiation in crystalline solids. The effects initially were opened for the X-rays, may occur for the optical radiation in photonic crystals. The dynamics of the femtosecond light pulse inside the linear PC is similar to diffraction of X-ray beam in a crystal at the Laue scheme. The pulse is spatially separated into two, called the transmitted and the diffracted pulses. Each of them, in turn, is separated into two pulses with different propagation velocity (temporal separation), which is associated with redistribution of the field of an initial pulse between the layers of PC. The mechanism of this redistribution is the same as in the case of the Borrmann effect, i.e . field of each pulse is localized mainly in the layers of PC to one or another type. Parameters of distribution of each pulse is determined by the optical characteristics of the layers. PC was fabricated by electrochemical etching of silicon. It consists of 400 pairs of alternating layers with optical thickness 600 and 680 nm. Refraction indices of layers are 1.5 and 1.7. Photonic band gap center is at 2620 nm. Experimental setup was based on Ti:sapphire laser with a wavelength centered at 800 nm, with a pulse duration of 100 fs and a pulse repetition rate of 80 MHz. Spatial laser pulse splitting into two beams was observed. Direction and intensity of transmitted and diffracted beams coincides with theoretically predicted.