Theoretical optimization of complete forbidden bands in woodpile-type photonic crystals

Based on the plane-wave method, the optical properties of complete forbidden bands of woodpile structure photonic crystal with an entire lattice rotation of 45°in the x-y plane were theoretically studied in terms ofheight-to-pitch ratios, filling factors, and rotation angles. The calculated results show that the gap to mid-gap ratio changes slightly with a filling fraction ranging from 0.25 to 0.30. The optimum height-to-pitch ratio is about 1.3. The gap to mid-gap ratio reaches more than 0.18 when the rotation angle increases from 40°to 50°and the maximum gap to mid-gap ratio of 0.2 remains unchanged for the rotation angle from 42°to 48°with a constant height-to-pitch ratio of 1.3. The gap to mid-gap ratio reaches the maximum value of 0.2 when the height-to-pitch ratio is 1.3. This woodpile-type photonic crystal can provide large band gaps within a wider parameter range, which makes it convenient to manufacture three-dimensional photonic crystals in the laboratory.