title: Self-collimated waveguide bends and partial bandgap reflection of photonic crystals with parallelogram lattice.
abstract: The photonic crystal structure with parallelogram lattice, capable of bending a self-collimated wave with free angles and partial bandgap reflection, is presented. The equifrequency contours show that the direction of the collimation wave can be turned by tuning the angle between the two basic vectors of the lattice. Acute, right, and obtuse angles of collimating waveguide bends have been realized by arc lattices of parallelogram photonic crystals. Moreover, partial bandgap reflection of the parallelogram lattice photonic crystals is validated from the equifrequency contours and the projected band structures. A waveguide taper based on this partial bandgap reflection is also designed and proved to have above 85% transmittance over a very wide operating bandwidth of 180 nm.
authors.affiliation: Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China. gdingshan@163.com
authors.forename: Dingshan
authors.initials: D
authors.lastname: Gao
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Zhou
authors.forename: David S
authors.initials: DS
authors.lastname: Citrin