Взаимодействие импульсного излучения с фотонным кристаллом

The features of propagation of broadband signals through photonic crystals are studied. The spectrum of broadband signals corresponds to both allowed and forbidden frequency ranges for the transmission of radiation in the crystal. For this purpose by finite differences time domain (FDTD) method the propagation of single Gaussian pulses of different spectral content through the photon crystal representing the two-dimensional square grid formed by the cylindrical GaAs elements is investigated. It is shown that such structure possesses the single complete forbidden band at rather small density of compositing of elements. Two types of pulses are analyzed. The first one is formed by electromagnetic oscillations with a frequency corresponding to the first allowed zone. The second one was excited at a frequency of the forbidden band. The time diagrams received in different points inside and outside the crystal, and patterns of space distribution of a field in it in different time points are analyzed. The considerable reduction of velocity of propagation of the signals formed by oscillations with the forbidden band frequency compared with velocity of light in the environment is found. As a result of the research the possibility of localization of a pulse radiation in a photon crystal of the finite sizes is proved.