Study on sampled waveguide grating with anti-symmetric periodic structure

An anti-symmetrically sampled Bragg grating (ASBG) with single mode waveguide is proposed and investigated for the first time. Based on anti-symmetric periodic structure, the coupling coefficient between the forward and backward guided modes becomes zero, thus nearly no light is reflected. Besides, the equivalent tilted grating effect with radiation mode coupling is found. If another anti-symmetrically sampling structure is imposed to form a sampled grating, the 0th sub-grating can be avoided, while the ± 1st sub-gratings are adjusted as uniform gratings with normal performances. This will be very benefit for some special applications such as distributed feedback (DFB) lasers based on Reconstruction-equivalent-chirp (REC) technique where 0th order resonance can be avoided. In addition, error analysis for the proposed structure is also performed for practical applications.