Surface plasmon resonance based tunable D-shaped single polarization filter at the communication band

Abstract

A surface plasmon resonance based D-shaped tunable and broadband single-polarization filter is proposed. The complex propagation constants and the guided modes’ corresponding field profiles are calculated using the full-vector finite element method based COMSOL Multiphysics v5.0 software. From the simulation study, it is found that the confinement losses of the desired x-polarized mode are 0.17 dB/cm, and 0.30 dB/cm at the resonance wavelength of 1.31 µm, and 1.55 µm, respectively, while the losses for y-polarized unwanted guided mode are 736.30 dB/cm, and 573.32 dB/cm at the mentioned wavelengths, respectively. It is also evident that the proposed fiber offers a crosstalk of 625.10 dB at the wavelength of 1.31 µm, and 495.31 dB at the wavelength of 1.55 µm with the corresponding bandwidth of 490 nm and 485 nm over which the crosstalk is more than 20 dB for a fiber length of 1.0 mm. The study also underpins that the resonant peak shifts linearly with the change of lattice constant, radius of the gold-coated channel in the polished surface, and the size and the distance between the tuning air holes of the proposed filter. Hence, this filter can be a potential fit for micro-integration in optical systems.