90° bent hollow waveguides formed by distributed Bragg reflector

90° bent hollow waveguides with distributed Bragg reflectors (DBR) in silicon substrate are proposed. The air core was embedded by Si
3
N
4
/SiO
2
multilayer. The two-dimensional (2-D) finite-difference time-domain (FDTD) method is used to simulate bending transmission efficiencies of the 90°-bent waveguides. The lowest 90° bending loss is around 0.8dB. This waveguide can be used in integrated planar light wave circuits.