In this paper, we propose and numerically analyze a novel design for a high sensitivity refractive index (RI) sensor based on long-range surface plasmon resonance in H-shaped microstructured optical fiber with symmetrical dielectric-metal-dielectric waveguide (DMDW). The influences of geometrical and optical characteristics of the DMDW on the sensor performance are investigated theoretically. A large RI analyte range from 1.33 to 1.39 is evaluated to study the sensing characteristics of the proposed structure. The obtained results show that the DMDW improves the coupling between the fiber core mode and the plasmonic mode. The best configuration shows 27 nm of full width at half maximum with a resolution close to 1.3 × 10 −5 nm, a high sensitivity of 7540 nm/RIU and a figure of merit of 280 RIU −1 . Additionally, the proposed device has potential for multi-analyte sensing and self-reference when dissimilar DMDWs are deposited on the inner walls of the side holes. The proposed sensor structure is simple and presents very competitive sensing parameters, which demonstrates that this device is a promising alternative and could be used in a wide range of application areas.

We present the design of a porous-core PCF with elliptical holes in the core that achieved low loss, high birefringence, and flattened dispersion for guiding terahertz waves. The finite element method is used to study the properties of the designed waveguide in detail: effective material loss, birefringence, confinement losses, and dispersion. Simulation results show that the proposed structure exhibits simultaneously high modal birefringence of 1.32 × 10 −2 and a flattened dispersion over a broadband of 1.28 THz. Then, polarization splitters, based on both symmetric and asymmetric porous-core PCF structures, are designed and evaluated at 1 THz. We show that this kind of device exhibits a strong polarization-dependent coupling behavior. Numerical results show that the configuration based on dual-core waveguide with asymmetric cores can achieve a 10.9 cm long splitter with a broadband of 0.306 THz for x-polarization and 0.23 THz for y-polarization. Finally, this paper offers an effective method to design an ultrawideband polarization beam splitter to operate in the THz region, which might be relevant for future applications in technical areas, such as spectroscopy, sensing, and high-speed data transmission.

We report on the temperature sensitivity of the birefringence properties of a special kind of photonic crystal fiber containing two side holes filled with Indium metal. The modulation of the fiber birefringence is accomplished through the stress field induced by the expansion of the metal. Although the fiber was made at low gas pressures during the indium infiltration process, the birefringence showed anomalous property at a relatively low temperature value, which is completely different from those reported in conventional-like fibers with two holes filled with metal. By modeling the anisotropic changes induced by the metal expansion to the refractive index within the fiber, we are able to reproduce the experimental results. Our results have practical relevance for the design of devices based on this technology.

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This paper presents the design and analysis of a surface plasmon resonance (SPR) sensor in a photonic crystal fiber (PCF) platform, where graphene is used externally to attain improved sensing performance for an aqueous solution. The performance of the proposed sensor was analyzed using the finite element method-based simulation tool COMSOL Multiphysics. According to the simulation results, the proposed sensor exhibits identical linear characteristics as well as a very high figure of merit (FOM) of 2310.11 RIU−1 in the very low detection limit of 10−3. The analysis also reveals the maximum amplitude sensitivity of 14,847.03 RIU−1 and 7351.82 RIU−1 for the x and y polarized modes, respectively, which are high compared to several previously reported configurations. In addition, the average wavelength sensitivity is 2000 nm/RIU which is comparatively high for the analyte refractive index (RI) ranging from 1.331 to 1.339. Hence, it is highly expected that the proposed PCF-based SPR sensor can be a suitable candidate in different sensing applications, especially for aqueous solutions.

In this paper, the capabilities of chromatic dispersion compensation of a photonic crystal fiber with a hexagonal distribution of circular air holes was investigated. The vector finite element method with scattering boundary condition was used to analyze a set of configurations of the fiber in which the distance between air holes’ centers was modified. With this method it was possible to obtain the values of chromatic dispersion and confinement factor in the C fiber band. The best suited configurations were tested in a 160 km optical link with a bit rate of 40 Gbps. The performance was evaluated by measuring the bit error rate for a set of 20 channels with channel spacing of 100 GHz. The simulation results showed that is possible to reach values of chromatic dispersion as low as $- 850{{{\rm{ps}}} \over {{\rm{nm}} \middot {\rm{km}}}}$ , confinement losses close to 10−3 dB/km and good BER results in the order of 10−17 for a wavelength of 1550 nm.

Análisis del rendimiento de un conversor modal basado en una fibra de cristal fotónico doble núcleo asimétricaErick Reyes-Vera 1,2, * , J. Úsuga 2 , J. Acevedo-Echeverry 2 , N. Gómez-Cardona 2 , M. Varón 1 Colombia, A.A. 055051, Bogotá, Colombia. 2. Department of Electronic and Telecommunications Engineering, Instituto Tecnológico Metropolitano, A.A. 50034, Medellín, Colombia. (*) E-mail: eereyesv@unal.edu. Department of Electrical and Electronic Engineering, Universidad Nacional de ABSTRACTIn this paper a novel modal converter based on an asymmetric dual-core photonic crystal fiber is proposed and numerically analyzed by using the full-vector finite element method. This converter allows mode conversion between the LP01 and LP11 modes, and the LP01 and LP21 modes. These modes are obtained at 1.55 µm. In addition, it was found that the operating wavelength of this device has a great dependence on the different geometric parameters of the structure, such as the diameter of the holes and the pitch as well. Finally, a compact device that can be used in the O + S + C + L + U bands with efficiency greater than 80% and a total length of 2 mm was obtained. This is a very interesting alternative to fabricate new all-fiber optic devices that could be implemented in mode division multiplexing systems.Key words: Mode-division multiplexing; mode converter; photonic crystal fiber; dual-core optical fiber. RESUMENEn este artículo, un novedoso conversor modal basado en una fibra de cristal fotónico con núcleos asimétricos es propuesto y analizado a través de la implementación del método de elementos finitos. Este dispositivo permite la conversión modal entre los modos LP01 con el LP11 y LP01 con el LP21 a una longitud de onda de 1.55 µm. Adicionalmente, hemos encontrado que la longitud de onda de operación de este tipo de dispositivos presenta una fuerte dependencia con los parámetros geométricos de la estructura tales como el diámetro de los agujeros y la distancia entre ellos. Finalmente, se obtuvo un dispositivo fotónico compacto que puede ser empleado en las bandas O + S + C + L + U con eficiencias superiores al 80 % y una longitud total de 2 mm. Esta es una alternativa interesante a la hora de fabricar nuevos dispositivos totalmente integrados a fibra óptica que puedan ser implementados en sistemas de multiplexación por división modal.Palabras clave: multiplexación por división modal; conversor modal; fibra de cristal fotónico; fibra óptica doble núcleo. REFERENCES AND LINKS / REFERENCIAS Y ENLACES[1] D. J. Richardson, J. M. Fini, and L. E. Nelson, "Space-division multiplexing in optical fibres," Nat. Photonics, vol. 7, no. April, pp. 354-362 (2013 [9] Y. Weng, X. He, J. Wang, and Z. Pan, "All-optical ultrafast wavelength and mode converter based on inter-modal four-wave mixing in few-mode fibers," Opt. Commun., vol. 348, pp. 7-12 (2015).https://doi.org/10.1016/j.optcom.2015.03.018[10] T. Hellwig, T. Walbaum, and C. Fallnich, "Optically induced mode conversion in graded-index fibers using ultra-short laser pulses," ...

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