Controlling ultrashort pulses shape using one-dimensional graded index photonic crystals

Design of Flat Defects’ Band in One-Dimensional Coupled-Cavity Photonic Crystal Waveguides for Transmitting Ultrashort Pulses

“…By optimizing geometrical parameters such as the number of distributed Bragg reflection layers and edge layers, using the transfer matrix method, a flat defects' band in the wavelength range of 740 − 860 (nm) has been designed, suitable for transforming ultrashort pulses up to 30-fs pulse. Up to now, in conventional CCWs, at least 200 thin film layers [15] or graded index materials [17,18] have been used for creating a flat passband in the band gap spectrum, while constructing such structures are complicated from the manufacturing point of view. Our proposed structure is composed of 29 layers with a total thickness of 3.78 μm without applying graded index materials and possessing nearly a 100% transmission which is higher than the previously proposed structures.…”

“…Thus, from the manufacturing point of view, constructing such a structure is very complicated, due to the existence of many layers in the system. Recently, Fathollahi-Khalkhali et al [17,18] have proposed a CCW composed of graded index dielectric materials and liquid crystals, which can pass an ultrashort pulse through the structure, while almost all original properties of the pulse are preserved. In similarity with the previous case, constructing multi-layers thin films with graded and precise refractive index is complicated.…”