Numerical analysis of an all-fiber plasmonic polarization filter using dual elliptical gold thin layers deposited photonic crystal fiber

Abstract

In order to solve the problems of high performance and small size incompatibility, as well as limited bandwidth, of traditional polarization filters in optical communication systems, this work presents an all-fiber polarization filter using dual elliptical gold layer deposited photonic crystal fiber by the finite element tool. The gold layers are plated on the inside of the two elliptical holes to create surface plasmon resonance effect, which cause the signal intensity in x-polarized direction to be much greater than that in y-polarized direction. The simulation results illustrate that when hole-to-hole pitch Λ is 2.0 μm, cladding hole diameter d 1 is 2.0 μm, two inner-holes’ diameter d 2 is 0.3 μm, spacing between two inner-holes d s is 0.755 μm, the major axis length of elliptical holes a is 2.0 μm, the minor axis length of elliptical holes b is 0.97 μm, the gold thin layer t is 100 nm, the proposed PCF filter exhibits good filtering performance at the communication wavelength of 1.55 μm, where the confinement loss in x- and y-polarized direction are 303.91 dB cm−1 and 0.06 dB cm−1, respectively. The crosstalk and operating bandwidth improve with the increment of device’s length, the 800 μm-long PCF filter possesses the maximum crosstalk of −211.14 dB and the bandwidth of 600 nm. Finally, the experimental scheme is also discussed. We believe that this photonic filter can play a significant role in optical communication, optical sensing, spectral analysis, and other related fields.