Slow-light technology is a key technology for realizing optical buffers in all-optical networks.In order to realize slow light with low group velocity and large bandwidth

this paper designs a novel waveguide structure

which is based on two-dimensional square lattices with the dielectric cylinder rotated by-45°so as to produce line defects

achieves slow light transmission and applies it to the optical buffer technology.In addition

it optimizes the slow light performances of the structure further by changing the radius of the dielectric cylinder and the width of the waveguide

conducts calculation and simulation by using the supercell-based plane wave expansion method

obtaining the dispersion curve of the defected mode.Furthermore

it analyzes in detail the properties of transmission group velocity and group velocity dispersion of light in waveguide and achieves the maximum group speed of only 0.007 89 c（cis the speed of light in vacuum）

and the group velocity dispersion in the range-106

1

06 ps2/km.When a designed 1mm-long photonic crystal structure is applied to the optical buffer

it can achieve the maximum cache time of 2.778 ps and the maximum cache capacity of 145.98 bit.