Efficient Polarization Filter Design Based on Plasmonic Photonic Crystal Fiber

Abstract

A novel selectively metal-filled spiral photonic crystal fiber with an elliptic core is introduced and analyzed. The cladding air holes of the suggested design are arranged in spiral arms that are distributed in an elliptical form. In this paper, the dispersion characteristics and loss spectra of the reported design are studied through the full-vectorial finite-element method. The suggested design has advantages in terms of highly polarization-dependent coupling between x- and y-polarized core modes and higher order surface plasmon polariton (SPP) modes. It is evident from this study that the core modes can be separated from each other by changing the structure parameters. In addition, the resonance points at which the coupling between the core modes and SPP modes occurs can be tuned. Moreover, the coupling tunability of the proposed design can be increased by filling the cladding air hole with multiple metal wires. This novel structure is suitable for the design of filter-based applications. At wavelength $\lambda = 1.013$ μm, the loss of the x-polarized core mode is equal to 77.04 dB/mm, while it is only 2.765 dB/mm for the y-polarized core mode with single metal rod. However, for two metal rods, the losses for x- and y-polarized core modes are increased to 94.1 and 6.424 dB/mm, respectively, at $\lambda = 0.98$ μm.