A novel method for synthesizing arbitrary-shape triangular-spectrum fiber Bragg gratings (TS-FBGs) is proposed. It involves the use of a discrete layer peeling method for exploiting initial guess and a simulated annealing method for optimizing the desired grating parameter. By comparing it to the reported TS-FBGs synthesis methods, the proposed method has advantages of reducing the maximum index modulation and smoothing index modulation profile simultaneously. We employ the proposed method to synthesize FBGs with symmetric, asymmetric, and right-angled triangular spectrum, all of which have the low and smooth index modulation profiles. The synthesized gratings can act simple and cost-effective wavelength-interrogation devices in optical sensor systems.
A new structure of single polarization single mode (SPSM) microstructured polymer optical fiber (mPOF) is proposed
and numerically analyzed by using a full vector finite element method with anisotropic perfectly matched layers. The
cutoff wavelength of two linearly polarized states can be design by varying the structure parameters of mPOF. The
confinement loss are also numerically calculated and optimized at communication wavelength of polymer optical fiber
(POF) of 650 nm. From the numerical results it is confirmed that the proposed fiber is low-loss SPSM mPOF within the
wavelengths ranging from 0.63 μm to 0.73 μm, where only the slow-axis mode exists and the confinement loss is less
than 0.05 dB/m.