Showing 10 results for Optical Fiber
A.k Gautam, V Mishra,
Volume 5, Issue 1 (1-2011)
Abstract
In this Article dispersion characteristic of conventional optical waveguide with helical winding at core – cladding interface has been obtained. The model dispersion characteristics of optical waveguide with helical winding at core-cladding interface have been obtained for five different pitch angles. This paper includes dispersion characteristics of optical waveguide with helical winding, and compression of dispersion characteristics of optical waveguide with helical winding at core-cladding interface for five different pitch angles. Boundary conditions have been used to obtain the dispersion characteristics and these conditions have been utilized to get the model Eigen values equation. From these Eigen value equations dispersion curve are obtained and plotted for modified optical waveguide for particular values of the pitch angle of the winding and the result has been compared.
H Pakarzadeh, K Nielsen, A. C Brunetti, K Rottwitt, A Zakery,
Volume 6, Issue 2 (10-2012)
Abstract
A polymethylmethacrylate (PMMA) microstructured polymer
optical fiber (mPOF) is fabricated and characterized. Using the cut-back
technique the fiber loss is measured which is higher than the step-index silica
fibers. Through a novel experimental scheme, the backward Stokes spectrum of
the fabricated mPOF is recorded over a range exceeding 3000 cm‑1
during the cut-back method and compared with that of step-index silica fiber.
Especially, the gain coefficient of the Raman peak at 2950 cm‑1
is directly measured, that is without comparing with other known material. The
results show a very good agreement with those obtained through other
experimental schemes.
Mr Hamed Nikbakht, Prof Hamid Latifi, Ms Tahereh Amini, Dr Mohammad Ismail Zibaii,
Volume 8, Issue 2 (7-2014)
Abstract
In this paper, a tapered tip optical fiber probe sensor for localized refractive index (RI) measurements is presented. This sensor’s interaction with analytes is confined to a few micro-meters which makes it a promising candidate for in-vivo or even intra-cellular RI monitoring. This tapered tip was simply fabricated by etching optical fiber with hydrofluoric acid to a conic shape with a sub-micrometer aperture. The sensor was calibrated for RI measurement using different concentrations of NaCl in water. Limit of detection of 6.7×10-5 RIU was achieved for this low-cost sensor.
Dr. Hassan Pakarzadeh, Dr. Gholamreza Honarasa,
Volume 8, Issue 2 (7-2014)
Abstract
In this article, the impact of input pump profile on the gain spectrum as well as the saturation behavior of one-pump fiber optical parametric amplifiers (FOPAs) is investigated. Since in practical circumstances, pump sources used for FOPAs have Lorentz-Gaussian profile instead of Gaussian, a more realistic case is considered for simulating FOPAs in this article. The results of simulations for the Gaussian and the Lorentz-Gaussian profiles show that a higher gain and a faster saturation are obtained for a pump with a Lorentz-Gaussian profile than a Gaussian pump. The results of this article provide a more realistic model for FOPAs.
Dr. Hassan Pakarzadeh, Ms. Masoume Bagheri,
Volume 9, Issue 2 (11-2015)
Abstract
In this paper, the gain spectrum and the saturation behavior of one-pump fiber optical parametric amplifiers (1-P FOPAs) are investigated by taking into account the fourth-order dispersion coefficient b4 in the analysis. The results show that it is necessary to consider b4 in the analysis when the wavelength difference between the signal and pump waves is large enough and/or whenever the pump wavelength approaches to the zero-dispersion wavelength (ZDW) of the fiber. Also, it is shown that by increasing the value of b4, the gain value is increased and the saturation power is decreased. Finally, the simulation results are compared with the available experimental data and a very good agreement is obtained.
M. Sc. Jalil Jafari, Dr. Rahman Nouroozi,
Volume 11, Issue 1 (1-2017)
Abstract
For a fiber optical surface plasmon resonance (SPR) sensor a short part of its cladding should be removed to coat a thin layer of a metal. Usually this is problematic when an optical fiber with small core diameter is used. In this paper, a new method using µliter droplet of the HF acid for short fiber optical taper fabrication is reported. Using this method in a multi-mode optical fiber with the core/cladding size of 50/125 µm a 2 mm long taper with 40 µm diameter is fabricated. Roughness of its surface is investigated using an atomic force microscopy. The measured mean value of the roughness is about 8 nm. A 60 nm thin layer of pure silver is coated on the taper surface in order to investigate its performance using a fiber optical SPR sensor. Using this SPR fiber sensor measurement of the lead concentrations in water ranging from 0.1 to 10 part per million (ppm) is reported.
Saeed Azad, Roghaieh Parvizi, Ebrahim Sadeghi,
Volume 12, Issue 2 (12-2018)
Abstract
This work presents ZnO nanorods coated multimode optical fiber sensing behavior in response to ethanol solution. The sensor operates based on modulation of light intensity which arises from manipulation of light interaction with the ambient environment in sensing region. For this purpose, two steps are experimentally applied here; etching and then coating fiber with ZnO nanorods to provide stronger evanescent waves causing an enhanced interaction. Long length of fiber (15 mm) was etched uniformly and then well-ordered ZnO nanorods were grown hydrothermally on the core of optical fiber. Fiber coated with ZnO demonstrated an enhanced sensing performances such that response time decreased to 0.6s, linearity increased to 97% and sensitivity improved. Applicable features of the proposed device such as fast response time and high linearity make it favorable candidate for fiber optic sensing applications.
Zahra Saghi,
Volume 15, Issue 2 (7-2021)
Abstract
Square-core optical fiber is one of the modern optical fibers used in many fields such as astronomical spectroscopy, laser cutting and thermal applications of lasers and beam shaping optics. In this paper, an optical fiber that has a square core with a side of 55 µm is designed for propagating laser light at a wavelength of 1060 nm. Then, using numerical analysis by finite element method (FEM), the distribution of electric and magnetic fields with different polarizations and magnetizations is analyzed for the first three propagating modes of the optical fiber. In the following, the changes of total energy density and power flow are investigated. Finally, the results of the figures and plots are discussed completely.
Ehsan Adibnia, Majid Ghadrdan, Mohammad Ali Mansouri-Birjandi,
Volume 17, Issue 2 (6-2023)
Abstract
This research addresses the complexities and inefficiencies encountered in fabricating fiber Bragg gratings (FBGs), which are crucial for applications in optical communications, lasers, and sensors. The core challenge lies in the intricate relationship between fabrication parameters and the FBG's physical properties, making optimization time-consuming. To circumvent these obstacles, the study introduces an artificial intelligence-based approach, utilizing a neural network to predict FBG physical parameters from transmission spectra, thereby streamlining the fabrication process. The neural network demonstrated exceptional predictive accuracy, significantly reducing the parameter prediction time from days to seconds. This advancement offers a promising avenue for enhancing the efficiency and precision of FBG sensor design and fabrication. The research not only showcases the potential of artificial intelligence in revolutionizing FBG production but also contributes to the broader field of optical technology by facilitating more rapid and informed design decisions, ultimately paving the way for developing more sophisticated and sensitive FBG-based applications.
Morteza Janfaza, Hamed Moradi, Arsalan Jalil,
Volume 17, Issue 2 (6-2023)
Abstract
In this study, we present the findings derived from our simulation and experimental investigation of a distributed optical fiber acoustic sensor. The proposed sensor operates by utilizing the self-interference of Rayleigh backscattering. When the optical pulse propagates through the optical fiber, the phase of the Rayleigh backscattered light changes at the location where the acoustic signal is present. This phase change is then amplified through the self-interference of two Rayleigh backscattered beams in the Michelson interferometer scheme. This study aims to present the Phase Generated Carrier (PGC) demodulation method along with the arctangent function (ATAN) and the Coordinate Rotation Digital Computer (CORDIC) algorithm. This method offers a simple and efficient algorithm for computing hyperbolic and trigonometric functions. The system allows for the detection of acoustic waves caused by sinusoidal disturbances with a spatial resolution of approximately 20 m.
