Nelson Gomez-Cardona

Bloch-like surface waves (BLSWs) excited in side-polished photonic crystal fibers (PCFs) combine high refractive-index sensitivity with narrow resonances. This work investigates two- and three-nanostrip TiO₂ coatings on a D-shaped PCF to characterize the trade-off between refractometric sensitivity and spectral performance. Finite-element and eigenmode-expansion simulations show that the inter-strip gap (GAP) modifies BLSW coupling, resonance linewidth, and resonance depth. At the smallest simulated gap (0.05 μm), three 10-μm-wide strips achieve 8884 nm/RIU, approximately 17% higher than the single-strip reference. The two-strip design better balances sensitivity, linewidth, and resonance depth. The proposed platform may support high-resolution, localized refractometric measurements relevant to non-destructive monitoring.

Bloch-like surface waves (BLSWs) are electromagnetic waves generated at the interface between a dielectric medium and a photonic crystal. BLSWs have significant potential for sensing applications, since their electromagnetic fields are tightly confined near the interface, reaching comparable sensitivities to those of surface plasmon polariton (SPP)-based devices, but with higher figures of merit (FOM). This work explores a sensor based on BLSW at the interface formed by a TiO₂ thin film deposited on the flat surface of a laterally polished photonic crystal fiber (PCF). The performance of the sensor is studied when the TiO₂ film is partially removed, transforming the nanolayer into a nanostrip. The results of this study contribute to the optimization of the sensing performance of the proposed structure.

This study focuses on the analysis of the spectral response of all-pass micro-ring resonators (MRRs), which are essential in photonic device applications such as telecommunications, sensing, and optical frequency comb generation. The aim of this work is to generate a synthetic dataset that explores the spectral characteristics of the expected transmission spectra of MRRs by varying their structural parameters. Using numerical simulations, the dataset will allow the optimization of MRR performance metrics such as free spectral range (FSR), full width at half maximum (FWHM), and quality factor (Q-factor). The results confirm that variations in geometric configurations can significantly affect MRR performance, and the dataset provides valuable insights into the optimization process. Furthermore, machine learning techniques can be applied to the dataset to automate and improve the design process, reducing simulation times and increasing accuracy. This work contributes to the development of photonic devices by providing a broad dataset for further analysis and optimization.

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.

Passive optical tapping can be implemented by stacking multiple layers of polydimethylsiloxane (PDMS), which is used as planar waveguides for the transmission and capturing of light. Once the main waveguide is installed in the communications system, each additional stacked waveguide represents an optical sniffer where it is possible to intercept the data from an input optical fibre, allowing the information to also flow to the output fibre unnoticeably from the point of view of the transmitter. The waveguides can be stacked or removed, making it a dynamic device that overcomes the limitations of previous designs, and the optical sniffer shows fixed implementation. In addition, it is demonstrated that PDMS is a versatile material that permits the control of the coupling of light among the waveguides, depending on its properties, and the thickness of each waveguide is also critical for the performance of the device. Furthermore, the experimental results are supported with a theoretical analysis that permits better understanding of the performance of the device, whose use can be extended to other applications, such as a passive optical hub or a signal combiner/splitter.

A compact tunable mode converter device based on the thermo-optically characteristics of liquid crystals (LCs) is proposed and numerically analyzed herein. The proposed mode converter consists of an asymmetric dual-core photonic crystal fiber (PCF) with a highly thermo-responsive LC core. The verification of the proposed mode converter was ensured through an accurate PCF analysis based on the vector finite element method. With an appropriate choice of the design parameters associated with the LC core, phase matching at a single wavelength is available in the important O-band wavelength region. The simulation results showed that high conversion efficiencies between LP₀₁ and LP₁₁ mode are readily achieved over a broad wavelength range from 1278 nm to 1317 nm. Likewise, the tunable capability of the proposed mode converter was evaluated when it was submitted to thermal changes; thus, we evidence the strong thermo-responsive dependence of the operating wavelength, mode conversion efficiency and full-width at the half maximum (FWHM) bandwidth. Finally, the fabrication tolerances of the devices were also investigated. Therefore, the thermo-responsive characteristics of this novel PCF mode converter can be of fundamental importance in the future space division multiplexing technology.

We propose a compact interferometer based on a dual-core transversally chirped microstructured optical fiber (MOF), which can be used as a highly sensitive, label-free, and selective biosensor. The air holes of the rings surrounding one core of the structure are functionalized for antibody detection by immobilization of an antigen sensor layer onto the walls of the holes. Changes in the thickness of the biomolecule layer can be detected as a function of the resonant wavelength in the transmittance spectrum. Numerical results demonstrate that the proposed biosensor could achieve a sensitivity of up to 5.6 nm/nm at 1600 nm and 4.7 nm/nm at 1440 nm, respectively. The sensor operation was optimized for the IR region, which allows the detection of biological agents.