Analytic method for fast design of aperiodic fiber Bragg grating devices

摘要

An analytic method for fast design of aperiodic fiber Bragg grating (AFBG) devices by use of Fourier mode coupling (FMC) theory is presented. AFBG devices, which are often used in practice, include the superstructure, phase-shifted FBG, and the apodized FBGs with Gauss, cosine, raised-cosine, Hamming, or Blackman windows, and include the in-fiber Fabry-Perot cavities formed by two AFBGs. The analytic solutions to the reflectivities of these AFBG devices are obtained on the basis of FMC theory, from which closed-form expressions for the relation between the AFBG structure parameters and their reflection properties are derived. According to these expressions, an analytic algorithm is established to quickly design AFBG devices with the desired reflection properties, which has linear complexity. The design of each AFBG device was achieved in ~50 ms on a general PC, and the reflection properties of the designed AFBG device were confirmed by using the transfer matrix method. This indicates that the analytic design methods proposed are highly efficient and sufficiently accurate.