Photon barrier and photon tunneling in optical waveguide structure

Based on the well-known electron coherent tunneling phenomenon, a photonic tunneling filter fabricated on an optical waveguide is proposed. The Bragg grating structure is applied as the photonic barrier. Two identical photonic barriers form a coherent resonance cavity or photon confinement quantum well so that at a specific wavelength in the forbidden band of the barrier, the photon can be tunneling through the waveguide with 100% transmission and very narrow bandwidth. Additionally, to facilitate the engineering design of this kind of photonic tunneling filter, a phase-shifted asymmetric-barrier structure is implemented. It is demonstrated that in this asymmetric-barrier structure, the tunneling wavelength is exactly the same as the Bragg wavelength of the grating, which is at the center of the barrier stop band. Some key parameters such as cavity/well and barrier lengths are investigated in order to control the filter bandwidth. Therefore the photon filter proposed should be easily designed for a specific wavelength and bandwidth and will have great applications in wavelength division multiplexing optic communication system and optical sensing. Finally it is pointed out that this tunneling filter is clearly related to the distributed-Bragg-grating-reflection laser diode.