We proposed a novel quasi-three dimensional (3D) photonic crystal (PC), which is composed of 2D PC and 1D distributed Bragg reflector (DBR) structures with a matching layer set between them. The band structures and reflectance of 1D DBR with changed thickness of the matching layer were calculated by 2D plane wave method and transfer matrix method respectively, while the dispersion diagram of the
quasi-3D PCWs both in GaAs/Al<sub>x</sub>O<sub>y</sub> (or Si/SiO<sub>2</sub>) and GaAs/AlAs PCWs were investigated using 2D plane wave method with supercells. Through adjusting the thickness of the matching layer, out-of-plane confinement by the effects of Bragg mirroring and total internal reflection can be achieved simultaneously. Using this quasi-3D PC waveguide structure, a wide transmission band was demonstrated both in GaAs/Al<sub>x</sub>O<sub>y</sub> (or Si/SiO<sub>2</sub>) and GaAs/AlAs material group.