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1 – 10 of 41Gurmeet Kaur, M.L. Singh and M.S. Patterh
Fiber nonlinearities are anticipated to impose transmission limitations due to the enhanced total interaction length in long‐haul dense wavelength division multiplexing…
Abstract
Purpose
Fiber nonlinearities are anticipated to impose transmission limitations due to the enhanced total interaction length in long‐haul dense wavelength division multiplexing (DWDM) optical transmission systems. The purpose of this paper is to analytically study the combined effect of stimulated Raman scattering (SRS) and four‐wave mixing (FWM) in the presence of amplified spontaneous emission (ASE) noise generated by erbium‐doped fiber amplifiers (EDFAs).
Design/methodology/approach
The paper presents analytical analysis of DWDM optical transmission systems in the presence of two significant fiber nonlinearities (SRS and FWM).
Findings
Simple expressions are derived to study the dependence of signal‐to‐noise ratio (SNR) on the amplifier spacing between two consecutive amplifiers.
Originality/value
The authors have analytically studied the combined effect of SRS and FWM in the presence of ASE noise generated by EDFAs. The novelty of the work is that it has considered all the three factors simultaneously and the expressions are derived for calculation of SNR.
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Gurmeet Kaur, M.L. Singh and M.S. Patterh
The current generation of light wave systems benefit from increased transmission distance by using optical amplification and increased capacity by using dense wavelength…
Abstract
Purpose
The current generation of light wave systems benefit from increased transmission distance by using optical amplification and increased capacity by using dense wavelength division multiplexing (DWDM) technology. The reach of present systems is limited by the noise contributed by the used amplifiers, combined with nonlinear effects from transmission. This paper aims to address these issues.
Design/methodology/approach
The nature and extent of degradations in the optical DWDM systems due to these limiting factors have been discussed in this paper.
Findings
It has been learnt that stimulated Raman scattering (SRS), four wave mixing (FWM) and amplified spontaneous emission (ASE) are the important factors in optical DWDM systems. These factors limit the system capacity of the transmission systems drastically.
Originality/value
It can be concluded from the discussion that while designing an efficient DWDM system, an optimization of the channel separation and the amplifier separation is required to minimize the nonlinear effects (FWM and SRS) along with the ASE noise introduced by inline optical amplifications.
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Fikri Serdar Gokhan and Gunes Yilmaz
The purpose of this paper is to demonstrate an effective and faster numerical solution for nonlinear‐coupled differential equations describing fiber amplifiers which have…
Abstract
Purpose
The purpose of this paper is to demonstrate an effective and faster numerical solution for nonlinear‐coupled differential equations describing fiber amplifiers which have no explicit solution. MATLAB boundary value problem (BVP) solver of bvp6c function is addressed for the solution.
Design/methodology/approach
Coding method with the bvp6c is introduced, signal evolution, threshold calculation method is introduced, gain and noise figure are plotted and superiority of the bvp6c solver is compared with the Newton‐Raphson method.
Findings
bvp6c function appears to be an effective tool for the solution fiber amplifier equations and can be used for different pump configurations of BFAs and RFAs. The excellent agreement between the proposed and reported results shows the reliability of the proposed threshold power calculation method.
Research limitations/implications
The paper eases the work of the fiber optic research community, who suffer from two point BVPs. Moreover, the stiffness of the signal evolution which is faced with high pump powers and/or long fiber lengths can be solved with continuation. This superiority of the solver can be used to overcome any stiff changes of the signals for the future studies.
Practical implications
The main outcome of this paper is the numerically calculation of the threshold values of fiber amplifiers without the necessity of the experiment. The robustness improvement of the solution is that the solver is able to solve the equations even with the poor guess values and the solution can be obtained without the necessity of analytical Jacobian matrix.
Originality/value
MATLAB bvp6c solver has proven to be effective for the numerical solution of nonlinear‐coupled intensity differential equations describing fiber amplifiers with two‐point boundary values. Beside the signal evolution, thresholds of Brillouin and Raman fiber amplifiers can also be calculated by using the proposed solver. This is a notable and promising improvement of the paper, at least from a fiber optic amplifier designer point of view.
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This paper aims to provide technical details of the techniques used for the remote detection of chemical compounds in a number of applications and also to highlight key…
Abstract
Purpose
This paper aims to provide technical details of the techniques used for the remote detection of chemical compounds in a number of applications and also to highlight key research themes.
Design/methodology/approach
Following a short introduction, this first considers remote gas detection using the DIAL technique. Remote gas cloud imaging is then discussed, and this is followed by a review of chemical warfare agent detection technologies. A selection of research activities and product developments aimed at remotely detecting explosives are considered and, finally, brief concluding comments are drawn.
Findings
Remote gas sensing is now a practical reality, and products are available which can remotely detect, identify, quantify and in some cases visualise a wide range of toxic and environmentally threatening gases. These satisfy numerous industrial, environmental and military applications. Remotely detecting explosives poses a significant technological challenge, and despite some commercialisation, it remains the topic of an extensive research effort, much involving LIBS and Raman techniques. Importantly, much of this work also has potential in non-military applications, with several developments being shown to detect various industrially important compounds.
Originality/value
This provides a technical insight into the techniques and products used in a range of remote chemical sensing applications.
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Sahar Feili, H.R. Sabouhi, Hassan Sobhani and M. Traz
This study aims to propose a new scheme for designing a high-sensitivity optical biosensor. For this, two agents have been considered: reflection-type micro-resonators…
Abstract
Purpose
This study aims to propose a new scheme for designing a high-sensitivity optical biosensor. For this, two agents have been considered: reflection-type micro-resonators, which filter the noise of the pump, and coupled-ring reflectors (CRRs), which are coupled to partial reflecting elements in the bus waveguide to create Fano-resonance. These two agents improve the sensor sensitivity and have low-power optical switching/modulation.
Design/methodology/approach
The proposed model is based on the coupling of the CRRs with the Fabry–Pérot cavity. The slope of the Fano-resonance line shape and consequently the sensitivity of the proposed CRRs are higher than those of conventional microring resonators.
Findings
The proposed scheme has many characteristics: CRRs have been used to create a higher slope of the Fano-resonance line shape; the sensitivity of the sensor shows improvement on the basis of reflection-type micro-resonators and by the removal of the pump noise; the designed sensor has low-power optical switching/modulation; and the modeling and designing of a novel high-sensitivity resonator is based on coupling the CRRs with the Fabry–Pérot cavity.
Originality/value
This study has proposed a new scheme for designing a high-sensitivity optical biosensor. This method is based on the improvement of the sensitivity by two agents: reflection-type micro-resonators, which filter the noise of the pump, and coupled-ring reflectors, which are coupled to partial reflecting elements in the bus waveguide to create Fano-resonance.
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M. McSherry, C. Fitzpatrick and E. Lewis
There are various temperature measuring systems presented in the literature and on the market today. Over the past number of years a range of luminescent‐based optical…
Abstract
Purpose
There are various temperature measuring systems presented in the literature and on the market today. Over the past number of years a range of luminescent‐based optical fibre sensors have been reported and developed which include fluorescence and optical scattering. These temperature sensors incorporate materials that emit wavelength shifted light when excited by an optical source. The majority of commercially available systems are based on fluorescent properties.Design/methodology/approach – Many published journal articles and conference papers were investigated and existing temperature sensors in the market were examined.Findings – In optical thermometry, the light is used to carry temperature information. In many cases optical fibres are used to transmit and receive this light. Optical fibres are immune to electromagnetic interference and are small in size, which allows them to make very localized measurements. A temperature sensitive material forms a sensor and the subsequent optical data are transmitted via optical fibres to electronic detection systems. Two keys areas were investigated namely fluorescence based temperature sensors and temperature sensors involving optical scattering.Originality/value – An overview of optical fibre temperature sensors based on luminescence is presented. This review provides a summary of optical temperature sensors, old and new which exist in today's world of sensing.
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Xiao Fang, Yajie Zeng, Feng Xiong, Jiang Chen and Fei Cheng
Seepage of the dam is an important safety problem, which may cause internal erosion of the structure. In the field of seepage monitoring in civil engineering, the…
Abstract
Purpose
Seepage of the dam is an important safety problem, which may cause internal erosion of the structure. In the field of seepage monitoring in civil engineering, the distributed optical fiber sensing technology based on the temperature tracing method has been paid more attention due to its unique advantages of high sensitivity, good stability and high resolution. The purpose of this paper is to make a review of the existing related research, so as to facilitate the later scholars to understand and further study more systematically.
Design/methodology/approach
In this paper, three kinds of commonly used distributed fiber temperature measurement technologies are introduced. Based on the working principle, monitoring system, theoretical analysis, experimental research and engineering application of the fiber seepage monitoring technology, the present situation of dam seepage monitoring based on distributed fiber is reviewed in detail and their advantages and disadvantages are compared.
Findings
The thermal monitoring technology of seepage measurement depends on the accuracy of optical fiber temperature measurement (including the accuracy of the system and the rationality of the discrimination method), the correct installation of optical fiber and the quantitative analysis of temperature data. The accuracy of the current monitoring system can basically meet the existing measurement requirements, but the correct installation of optical fiber and the calibration of temperature data need to be further studied for different discrimination methods, and this field has great research value.
Originality/value
At present, there are many applications and research studies of optical fiber sensing in the field of structural health monitoring, and there are also reviews of related aspects. However, there is little or no review only in the field of seepage monitoring. This paper summarizes the research and application of optical fiber sensing in the field of seepage monitoring. The possibility of the gradient method to find its new prospect with the development of monitoring systems and the improvement of temperature resolution is discussed. The idea of extending the seepage monitoring method based on distributed optical fiber thermal monitoring technology to other monitoring fields is also given in the paper.
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Zhang Lei, Yingshan Chen, Zhiwen Liu, Wenjin Ji and Suqing Zhao
In this study, a highly sensitive and quantitative analysis method using surface-enhanced Raman scattering (SERS)-labeled immunoassay is adopted for bisphenol A bisphenol…
Abstract
Purpose
In this study, a highly sensitive and quantitative analysis method using surface-enhanced Raman scattering (SERS)-labeled immunoassay is adopted for bisphenol A bisphenol A (BPA) detection in water samples.
Design/methodology/approach
Primarily, an excellent SERS immuno-nanoprobe is prepared, which relays on Au/Ag core-shell nanoparticles tagged 4-mercaptobenzoic acid (4MBA) and labeled with specific antibody against BPA. Second, the coating antigen of 4,4-Bis(4-hydroxyphenol) valeric acid (BVA) coupling poly-L-lysine (PLL) conjugate (BVA-PLL) is fastened on the substrate. Based on competitive immunoassay, the antibody labeled on SERS immuno-nanoprobe will bind with the free BPA and BVA-PLL competitively.
Findings
A calibration curve was obtained by plotting the intensity of SERS signal of 4MBA at 1007 cm−1 versus the concentration of BPA. The results indicated that the limit of detection (LOD) for BPA is 1 ng/mL and present a great capacity for higher sensitivity. Furthermore, the method was able to quantitatively detect BPA in water samples, which was validated by high performance liquid chromatography (HPLC).
Originality/value
The method was developed based on competitive immunoassay, and the conjugate (BVA-PLL) was chosen as the coating antigen. Au/Ag core-shell nanoparticles played as the SERS active substrate and were labeled with Raman reporter. The value of this paper is supplying a wide potential for analysis of target analytes in the environmental monitoring and food safety.
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