Low-cost fabrication and characterization process for development of a sensitive optical fiber structure.

The structure of silica single-mode fiber (SMF) must be modified in order to develop optical fiber-based biosensors. To reduce the diameter of the optical fiber, a low-cost chemical etching method is very popular. The proposed chemical etching method is a simple, rapid, and cost-effective technique for removing the silica cladding up to a desired diameter. In the laboratory, hydrofluoric acid (HF acid, 40% concentration) is used for etching. A variation on etching is also proposed and tested with 40% HF as well as with magnetic stirring at the different speeds. The etching experiments are also carried out at different temperatures. The etching results of silica fiber are presented through a step-by-step procedure using a rapid and resource-efficient method for the fabrication of optical fiber-based biosensors. The etched diameter characterization is done using a calibrated compound microscope. The sensing experiment with unetched and etched optical fiber is also performed for the detection of different concentrations of glucose biomolecules.

Fabrication and diameter analysis of a single-ended SMF tip structure.

Optical fiber technology combined with surface plasmon resonance enables rapid, precise detection of chemical, biochemical, and biological parameters. Many hybrid optical fiber structures have been suggested in recent decades to increase the sensitivity of optical fiber biosensors. In this work, an optical fiber tip structure is fabricated on single-mode fiber (SMF) by etching in a hydrofluoric acid (40%) solution at room temperature. The proposed method of tip formation utilizing wet etching is efficient for fabricating the highly sensitive fiber structures that are required for the development of optical fiber-based biosensors. The diameter measurement of fabricated fiber tip formation is done using a compound microscope.

Synthesis and characterization of gold nanoparticles and graphene oxide for the development of optical fiber biosensors.

Optical fiber technology, in association with the phenomenon of surface plasmon resonance (SPR), has opened a new gateway for quick, easier, and accurate sensing of various chemical, biochemical, and biological parameters. Continuous efforts can be seen in the direction of increasing the sensitivity of the optical fiber biosensors; thus, many hybrid nanostructured optical fiber biosensors composing different nanomaterials, nanomaterial combinations, and different 2D materials have been proposed in the past few decades. This paper discusses the synthesis, characterization, and applications of nanoparticles to the most favorable noble metal for SPR biosensing, i.e., gold. The gold nanoparticles (AuNPs) were prepared by the Turkevich method, and the optical property of AuNPs was characterized using the UV-visible spectrophotometer and transmission electron microscopy (TEM) technique. In addition, the synthesis, characterization, and application of the oxide form the most explored 2D material, i.e., graphene, are also presented in this paper. The graphene oxide was synthesized using an easier and economical method, i.e., a modified Hummer's method, and an evaluation of the characteristics has been done by a UV-visible spectrophotometer and TEM results.

Optimized plasmonic reversible logic gate for low loss communication.

With the development of plasmonic optical waveguides, numerous nanostructures based on different materials can be fabricated in a controlled way. While doing reversible computing, reversible logic gates are the necessary requirement to reduce the loss of information with less power consumption. The proposed design of the Feynman logic gate is simulated by a cascading metal-insulator-metal optical waveguide based on Mach-Zehnder interferometers. The footprint of the proposed Feynman logic gate is ${62}\;{\unicode{x00B5}{\rm m}} \times 9\;{\unicode{x00B5}{\rm m}}$, the extinction ratio is 10.57 dB, and the insertion loss is ${-}{0.969}\;{\rm dB}$ and ${-}{1.191}\;{\rm dB}$, which is much better compared to an electro-optic-based exiting Feynman logic gate. The results are obtained by simulating the proposed structure using the finite difference time domain method and verified by using mathematical computation in MATLAB.