Equivalently tilted Bragg waveguide grating and its applications to photonic devices

Tilted Bragg grating (TBG) has been intensively investigated for photonic devices such as fiber sensors and on-chip filters. In this paper, we present that TBG can be equivalently realized by designing tilted sampled Bragg grating (TSBG), which is formed by superimposing the pre-designed tilted sampling structure on the basic grating. Since the basic grating is uniform and the sampling structure is in the order of micrometer, the fabrication of TSBG can be realized with one step of holographic exposure combined with another step of micro-lithography. We designed and simulated the equivalent light responses of the TSBGs as that of the target TBG in the photonic devices. As examples, a mode converter based on TSBG has been proposed, which can be used for add-drop filter in the wavelength division multiplexing (WDM) technology combined with mode division multiplexing (MDM) technology. We also investigate the core-to-cladding mode coupling of TSBG in single-mode fiber for fiber sensing as well as the spatial filter in the α- DFB laser. The proposed technique may pave a new way for different 2D gratings with good design flexibility and easy fabrication in various photonic devices.