In this paper, a novel design of circular photonic crystal fiber (C-PCF) gas sensor is presented and analyzed by full vectorial finite element method. The suggested design has a spiral porous core region to achieve high sensitivity. The geometrical parameters of the proposed sensor are studied to achieve high sensor sensitivity. The introduced C-PCF offers high sensitivity of 72.04 % at the wavelength of 1.33 μm. The reported sensor also offers a compact, accurate and useful tool for detecting harmful gases over a wide transmission band from wavelength of 1 μm to 1.8 μm.
Micro-structured fiber (MF) devices such as polarization rotators, polarization filters, and polarization splitters have been widely used in optical communication systems. The concept of multifunctional photonic device becomes a new trend in optical systems. Therefore, it is essential to propose a new and compact multifunctional MF widely known as photonic crystal fiber (PCF) devices. In this paper, a compact polarization splitter that operates at two telecommunication wavelengths (1.31 μm or 1.55 μm) is designed. The proposed splitter is based on plasmonic tellurite dual core PCF in order to split the x and y polarization modes at wavelengths of 1.31 μm or 1.55 μm at the same device length. The nematic liquid crystal is selectively infiltrated in the cladding air holes to increase the birefringence in the introduced design. Further, the central hole is filled by a gold nanowire. The simulation results are obtained by using full vectorial finite element method with perfect matched layer boundary conditions. The numerical results reveal that the suggested splitter can split the x and y polarized modes at λ=1.31 and 1.55 μm at a short device length of 131.0 μm. The obtained crosstalk is -38 dB and -48 dB with bandwidths of 58 nm and 48 nm at λ= 1.31 μm for x and y polarized modes, respectively. In addition, crosstalk of -56 dB and -47 dB are achieved with bandwidths of 124 nm and 88 nm at λ= 1.55 μm for x and y polarized modes, respectively.
A hexagonal shape surface plasmon photonic crystal fiber (PCF) biosensor is reported and studied numerically. The proposed design has three identical cores along the y-axis filled with liquid (analyte). Additionally, the central core is coated by a gold layer to facilitate the coupling among the plasmonic modes and the core fundamental modes. A full vectorial finite element method is used to analyze the proposed sensor with a perfectly matched layer boundary condition. Further, the particle swarm optimization (PSO) technique is used to optimize and improve the sensitivity of the presented sensor as well as reduce the sensor’s size. Through the optimization process, the diameters of the three cores, and the thicknesses of the gold layer are fluctuated. For a wavelength range 1.46-1.47, the sensitivity of the proposed sensor is 4000 nm/RIU.
A novel design of multiplexer-demultiplexer (MUX-DEMUX) based on channel waveguide on silicon dioxide (SiO<sub>2</sub>) is introduced and analyzed. The suggested structure consists of two neighboring channels infiltrated with nematic liquid crystal (NLC) material of type E7. The two channels are etched in the SiO<sub>2</sub> substrate. The electro-optic effect of the NLC is used to control the waveguide propagation condition using an external electric field. Additionally, a plasmonic wire is inserted between the two waveguides to enhance the suggested MUX-DEMUX in terms of compactness. The modal analysis of the y-polarized modes supported by the NLC MUX-DEMUX is carried out using full-vectorial finitedifference method (FVFDM). Further, the propagation characteristics through the reported design are obtained using full vectorial finite difference beam propagation method (FVFD-BPM). The design parameters of the NLC MUX-DEMUX have been studied to obtain an efficient waveguide coupling with a short device length. Moreover, the NLC MUXDEMUX has a compact device length of 1296 μm. The numerical results reveal that the reported MUX-DEMUX has a small insertion loss of 8x10<sup>-6</sup> dB with a good crosstalk better than -37 dB and -30 dB at the studied wavelengths of 1.3 μm and 1.55 μm, respectively. To the best of the authors’ knowledge, it is the first time to introduce a MUX-DEMUX based on channel on SiO<sup>2</sup> platform with a simple design and broadband operation.
In this paper, a highly sensitive surface plasmon photonic crystal fiber (PCF) biosensor is reported and studied to monitor glucose concentration. The suggested design is based on a well-known large mode area (LMA) single mode PCF infiltrated by a plasmonic material. Additionally, an etching process is applied to increase the biosensor sensitivity. The numerical analysis is obtained using a full vectorial finite element method (FVFEM). The suggested biosensor based on a commercial PCF with plasmonic rod achieves sensitivity as high as 7900 <i>nm</i>/RIU with corresponding resolution of 1.26 × 10<sup>-5</sup>RIU<sup>-1</sup>. The analysis also reveals that the proposed biosensor has a linear performance which is needed practically. Therefore, the reported biosensor has advantages in terms of fabrication feasibility and high linear sensitivity
In this paper, compact three trenched channel plasmonic microring resonator sensor (TTCP-MRRS) on a silicon-oninsulator substrate is proposed and analyzed. The three trenched waveguide is composed of three metal-gaps-silicon structure, where the optical energy is greatly enhanced in the narrow gaps. The full vectorial finite element method is used to numerically analyze the device optical characteristics as a biochemical sensor. As the optical field in the proposed structure has a large overlap with the upper-cladding sensing medium, the sensitivity is very high compared to other dielectric microring resonator sensors. The sensitivity is the ratio between the resonance wavelength shift and the cladding refractive index change, which is a key parameter to describe the sensor performance. The detection limit (DL), which is defined as the minimum refractive index change in the sensing medium that can be detected by the sensor system, is proportional to the resonance line width Δλ or inversely proportional to the resonance Q-factor. So, in order to properly evaluate the sensing performance of the proposed channel plasmonic microring resonator sensor, a figure of merit (FOM) can be defined as the number of resonance line width shift in response to a unit cladding refractive index change. The proposed (TTCP-MRRS) has a compact size and high sensitivity and can be integrated in an array form on a chip for highly-efficient lab-on-chip biochemical sensing applications.