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.