Slow light in a slot photonic crystal waveguide with asymmetric dielectric rods

A novel air slot photonic crystal slow light waveguide structure is proposed. The symmetry of the waveguide is broken by shifting the dielectric rods asymmetrically along the slot axis. When the photonic crystal lattice vector angle is greater than 60 degrees, it can make the performance of slow light more excellent. A triangular lattice photonic crystal with the lattice vector 90 degrees is obtained by rotating the cubic lattice 45 degrees counterclockwise. Five optimized structures are obtained by optimizing the width of the slot, the radius of the two rows of semicircular dielectric columns in the upper and lower air slots as well as the asymmetric movement of the two rows of dielectric rods near the slot. The dispersion curves of the guided mode, the corresponding group index and group velocity dispersion are analyzed using the plane wave expansion method. Finally, considering a criterion of restricting the group index variation within +/- 10% range and higher normalized delay bandwidth product, the best group refractive index is 272 with the corresponding normalized delay bandwidth product is 0.3009. The numerical results provide theoretical foundation for potential applications of optical buffer in photonic crystals field.