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This paper presents a single-polarization filter based on PCF with plasmonic layers of gold and indium tin oxide (ITO). The plasmonic materials are metallic gold and ITO coated on the inner walls of two extra-large vertically arranged air holes. The resonance effect is triggered by guided modes propagating through the silica core and coupling to the coating areas. The finite element method is used to analyze the properties of the filter for the two fundamental orthogonal polarizations. A filtering effect is achieved in the communication window by optimizing the structural factors as well as gold film and ITO deposition thicknesses. When the filter is 1 mm long, the obtained filtering effect is 1319.689 dB/cm for the y-polarization and 31.881 dB/cm for the x-polarization, thus efficiently attenuating the y-component at a communication window of 1.15 μm. With a filtering bandwidth of 602 nm, the proposed filter shows superior characteristics compared with previously reported results. Applications of the proposed plasmonic PCF-based filter can be found in polarization-maintaining and polarization-suppressing systems for optical sensing and broadband transmission.

This work presents photonic crystal fibres made up of four hexagonal shape of four rings. Four structures have been designed and configured. The structures show improvement in optical properties consecutively to achieve the optimum configuration. The full vectorial finite-element method is adopted for this work. COMSOL Multiphysics is used for the simulation. The results show a birefringence of 1.308 × 10−2 at 1.55 µm and tuneable double zero dispersion at wavelengths of 0.99 µm and 1.8 µm for x-polarisation mode. Also, the chromatic dispersion of − 24.062 ps/km nm and nonlinear coefficient of 30.32 W−1 km−1 are obtained at a telecommunication wavelength of 1.55 µm. The proposed photonic crystal fibre can be beneficial in nonlinear and supercontinuum applications since photonic crystal fibres of double zero dispersion demonstrate higher power spectral densities than single zero dispersion.

This paper presents a highly negative dispersion-compensating photonic crystal fiber (DC-PCF) with multiple zero dispersion wavelengths (ZDWs) within the telecommunication bands. The multiple ZDWs of the PCF may lead to high spectral densities than those of other PCFs with few ZDWs. The full-vectorial finite element method with a perfectly matched layer (PML) is used to investigate the optical properties of the PCFs. The numerical analysis shows that the proposed PCF, i.e., PCF (b), exhibits multiple ZDWS and also achieves a high negative chromatic dispersion of −15089.0 ps/nm·km at 1.55  μ m wavelength, with the multiple ZDWs occurring within the range from 0.8 to 2.0  μ m range. Other optical properties such as the confinement loss of 0.059 dB/km, the birefringence of 4.11 × 10 − 1 , the nonlinearity of 18.92  W − 1 k m − 1 , and a normalized frequency of 2.633 was also achieved at 1.55  μ m wavelength. These characteristics make the PCF suitable for high-speed, long-distance optical communication systems, optical sensing, soliton pulse transmission, and polarization-maintaining applications.