Design of a single-polarization single-mode photonic crystal fiber with a near-Gaussian mode field and wide bandwidth

Single-polarization single-mode (SPSM) fiber can efficiently eliminate polarization mode coupling, polarization mode dispersion, and polarization-dependent loss. Up to now, most single-polarization fibers have been designed based on form birefringence, which would result in a non-Gaussian field distribution and a small effective mode field area. In this paper, a novel structure of SPSM photonic crystal fibers based on the resonant coupling phenomena is proposed and analyzed by using a full-vector finite-element method with a second-order transparent boundary condition. From the numerical results it is confirmed that this fiber has a near-Gaussian mode field within the wavelength range from 1.46 to 2.2 μm, where only one polarized mode exists effectively, and the mode field area is about 79 μm(2) at the wavelength of 1.55 μm, matching that of the conventional single-mode fiber.