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Optical delay in defective photonic bandgap structures

A defective photonic bandgap (PBG) structure constructed of Si and SiO2 is proposed for the purpose of realizing optical delay in high speed optical communication. The transmissions of the PBG structure as a function of the thickness and number of the defect layers, as well as the period of the structure between two defects, are investigated theoretically by the transfer matrix method. An optical delay line working at a wavelength of 1.55 μm with the group velocity as slow as 1 × 107 m s−1 and a bandwidth of 8 × 1012 Hz can be achieved, which meets the requirement of transmitting a picosecond pulse with the duration of ~1.878 ps at a speed rate of 500 Gbit s−1.