Plasmonic materials, when properly illuminated with visible or near-infrared wavelengths, exhibit unique and interesting features that can be exploited for tailoring and tuning the light radiation and propagation properties at nanoscale dimensions. A variety of plasmonic heterostructures have been demonstrated for optical-signal filtering, transmission, detection, transportation, and modulation. In this review, state-of-the-art plasmonic structures used for telecommunications applications are summarized. In doing so, we discuss their distinctive roles on multiple approaches including beam steering, guiding, filtering, modulation, switching, and detection, which are all of prime importance for the development of the sixth generation (6G) cellular networks.

The Raman spectra of pure silica core fibres revealed the presence of molecular oxygen, which may be responsible for two absorption bands, one at 0.76 and the other at 1.27 Fm.There has been a renewal of interest in pure silica core fibres owing to their inherently low losses and dispersion between 1.2 and 1.6 pm. In this region, the main cause of attenuation is the presence of the OH absorption bands. A recent study of the loss spectrum of pure and fluorine-doped silica fibres of low OH content by Heitmann et aL' revealed the existence of a new absorption band at 1.273 pm, which always appears associated with another one located around 0.765 pm. They tentatively assigned these bands to the presence of crystallites in the silica matrix which could not be detected by x-ray analysis. We present here new evidence, from a Raman analysis of fibres, that suggests a different origin for these absorption bands.

All-dielectric nanophotonic devices are promising candidates for future lossless (bio)sensing and telecommunications applications.

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Nanostructures exhibiting large transverse magnetooptical Kerr effect (TMOKE) are required for magnetoplasmonic biosensing if the aim is the minituarization and integration into microfluidic devices. In this work, we present a general strategy to design nanoarchitectures with enhanced TMOKE, which consist of an arrangement of gold ribs deposited on an magneto-optical (MO) dielectric slab of Bi:YIG (bismuth-substituted yttrium iron garnet) with a SiO 2 substrate surrounded by water. Using the finite element method (FEM), we demonstrate numerically that the near-zero-transmittance condition is the most important requirement for high TMOKE values. This can be reached through geometric optimization of the nanoarchitecture by tuning the period, height, and width of the grating, thus leading to resonances at wavelengths where the MO dielectric slab has high MO activity. We also show that the TMOKE amplitude can be further increased if losses in metal ribs are reduced. For a magnetoplasmonic grating with optimized geometry, we demonstrated the potential detection of biologically relevant analytes with sensitivity in the order of 10 2 nm/RIU (refractive index unit). Since the nanoarchitecture proposed is experimentally feasible with, e.g., nanolithography techniques, one may expect that the design strategy may inspire the development of efficient magnetoplasmonic sensing platforms.

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We numerically demonstrate an all-dielectric approach for magnetically tunable add/drop of optical channels in dense wavelength division multiplexing applications. Our concept comprises a micro-ring resonator, with an inner magneto-optical disk, side-coupled to two waveguides. The simulation results, obtained within the ITU-T G.694.1 recommendation, indicate high performance add/drop of odd and even optical channels (along the entire C-band) by flipping the intrinsic magnetization of the disk. Since the simulations were performed with CMOS-compatible materials, it is hoped that the structure proposed here can be integrated into future ultrafast optical communication networks.

We investigate the plasmonic behavior of a fractal photonic crystal fiber, with Sierpinski-like circular cross-section, and its potential applications for refractive index sensing and multiband polarization filters. Numerical results were obtained using the finite element method through the commercial software COMSOL Multiphysics®. A set of 34 surface plasmon resonances was identified in the wavelength range from λ=630 nm to λ=1700 nm. Subsets of close resonances were noted as a consequence of similar symmetries of the surface plasmon resonance (SPR) modes. Polarization filtering capabilities are numerically shown in the telecommunication windows from the O-band to the L-band. In the case of refractive index sensing, we used the wavelength interrogation method in the wavelength range from λ=670 nm to λ=790 nm, where the system exhibited a sensitivity of S(λ)=1951.43 nm/RIU (refractive index unit). Due to the broadband capabilities of our concept, we expect that it will be useful to develop future ultra-wide band optical communication infrastructures, which are urgent to meet the ever-increasing demand for bandwidth-hungry devices.