Photonic crystals are artificially fabricated periodic dielectric structures. In recent years

a lot of theories and experiments on the application of photonic crystals have been studied. The two-dimensional photonic crystals have more advantage than one-dimensional photonic crystals and the three-dimensional ones

so the theory and application of two-dimensional photonic crystals are still one of the hottest themes in materials science and photonics science. There are various methods on studying transmission characteristics of photonic crystals: the plane wave expansion method(PWE)

the finite-difference time-domain (FDTD)

transfer matrix method (TMM)

and multiple scattering method (Order-N). Shangshen Feng

et al

. used the plane-wave method for quickly calculating a band structure of two-dimensional photonic crystal with triangular lattice

but their studies didn't take into account the square cylinder rods photonic crystals

and the corresponding transmission spectrum was not obtained. In this paper

the transfer matrix method is used to study the transmission characteristics of two-dimension cylindrical photonic crystals of square dielectric rods with different lattice structures

section areas and azimuth angles. In numerical simulation the Mur absorbing boundary conditions and periodic boundary conditions are used to eliminate non-physical reflection of electromagnetic waves considered the actual structure. The numerical studies show that the photonic band gap width depends on the center frequency and lattice structure

the square lattice is easier to form smooth photonic band gap and the larger cylinder-sectional area is

the wider band gap is. In the same conditions as other factors

azimuth angle of cylinder impacts the photonic crystal band gap. The numerical study shows in the design of smooth photonic band gap of the square dielectric rod

the square lattice structure is considered first

then try to make the cylinder section as large as possible

finally

the photonic band gap width and center frequency can be fine-tuned to reach design requirements by changing the cylinder azimuth angles. In particular

no literature has reported the results that the band gap can be adjusted by the position azimuth angle

which expands the research of two-dimensional photonic crystals.