A tapered fibre optics biosensor for histamine detection

Purpose: This paper aims to estimate the level of histamine in fish and fish products, as it is very important because of their implication in fish poisoning in humans; hence, ascertaining histamine levels in the aforementioned serves as a chemical index for spoilage. Design/methodology/approach: A technique was developed to immobilize an ordered multilayer of diamine oxidase (DAO) by means of chemical cross-linking on the biconical taper surface stepwisely alternating between chitosan, glutaraldehyde and the enzyme. A spectrophotometric signal results from horseradish peroxidase catalyzed reduction of H2O2, a secondary product of the oxidative deamination of histamine monitored at 450 nm. Findings: The biosensor showed a linear response range up to 1.5 mM, a good sensitivity of 0.64 mM-1 with detection and quantification limits towards histamine of 0.086 mM (15.8 ppm) and 0.204 mM (37.7 ppm) and a linear response range of 0-1.5 mM. It showed a response and recovery time of 14 sec and operational stability up to 40 repeated analyses without significant loss of sensitivity. Practical implications: The developed biosensor has a good potential for use in the quantitative determination of histamine in seafood. Originality/value: The paper described an outcome of an experimental work on tapered fibre optics (taper)-based biosensor coated with DAO embedded into a chitosan membrane to measure histamine

Raman fiber laser with highly non-linear fiber

This paper demonstrates the power performance of an asymmetrical distributed feedback Raman fiber laser (DF-RFL) employing 2 km of highly nonlinear fiber (HNLF). The forward-pumped architecture exhibited better threshold condition and higher output power alongside a broader spectral profile compared to a DF-RFL utilizing a standard transmission fiber. This experimental layout could offer better insight on flatter broadband gain compared to conventional DF-RFL

Bidirectionally-pumped remote L-band EDFA module utilizing stimulated Raman scattering

This research was centered on an enhanced bidirectionally-pumped remote L-band erbium-doped fiber amplifier (EDFA) module. The amplifier was backward-pumped using 1455 nm Raman laser while the SRS generated in the delivery line pumped the remote EDFA in the forward direction. Gain values around 12 dB and 9 dB were measured for input signal of 30 and 0 dBm respectively. Excellent gain flatness was observed for both input levels with similar maximum gain variation of only 1.2 dB. 30 dBm input produced high noise figures up to 11.6 at the shorter wavelengths which declined as the signal moved further across the L-band window. The same trend was observed for 0 dBm input where at 1570 nm, 12.1 dB noise figure was acquired and went down to 7.2 dB at 1605 nm. Gain and noise figure behaviors were attributed to the gain competition due to the presence of the SRS, which was inadvertently amplified as well. The use of longer EDF length or careful selection of the pump wavelength can be considered to optimize the amplifier design

High signal-to-noise ratio Q-switching erbium doped fiber laser pulse emission utilizing single layer trivial transfer graphene film saturable absorber

This paper presents the high signal-to-noise ratio (SNR) Q-switched erbium-doped fiber laser pulse emission using a commercial single layer graphene (SLG) film as a saturable absorber (SA). A sandwiched-type structure with transferred single layer SLG film between two fiber ferrules is formed to function as the SA. Q-switched pulse emission with repetition rate from 47.25 kHz to 67.39 kHz and round-trip time per oscillation from 7.42 µs to 10.36 µs are obtained from the laser cavity set-up. The SNR of 62.64 dB shows a good quality of pulse generation using the SLG film as SA. The effortless production of SLG is enabling factor to produce fast fabrication and low cost SA for application in Q-switched pulsed fiber lasers

Tunable ultra-long random distributed feedback fiber laser

A 72 km open-ended symmetrical tunable random distributed feedback fiber laser (RDB-FL) with different pumping schemes is presented in this study. The random distributed feedback was contributed by Rayleigh scattering in the single-mode fiber while distributed gain was provided by the effect of stimulated Raman scattering. The pumping schemes tested with the configuration was outward and inward pumping, where these would be backward and forward pumping in a non-symmetrical configuration of a fiber laser, respectively. The tuning range was also varied in conjunction with the different pumping schemes to determine the optimum performance. Random lasing in the RDB-FL was achieved by utilizing multiple scattering in the disordered gain medium to achieve resonance. With pump power limited to 1.5 W, the best threshold was measured as low as 1.4 W while the highest total output power was at 8 mW. In outward pumping configuration, the wavelengths that are within the maximum Raman gain (1555-1565 nm) show the best peak powers and total output power with a narrow linewidth, as low as 0.25 nm

Half-opened cavity random distributed feedback laser with FBG wavelength variation

The work presented in this paper is on a backward-pumped Raman random distributed feedback laser with half-opened cavity configuration. Rayleigh backscattering effects were realized in a 41 km fiber length that functioned as a virtual mirror at one fiber end while at the other end, a single fiber Bragg grating with different central wavelength is deployed as a reflector. Pump power threshold, output power and efficiency that corresponding to FBG wavelengths of 1546.8 nm, 1550.4 nm and 1557.7 nm are studied. The obtained results show that the peak reflection wavelength of FBG nearest to the first Raman Stokes shift gives better threshold and output power, hence, improves the efficiency of random lasing

L-band erbium-doped fiber amplifier pumped by 1455 nm laser source for repeaterless transmission systems

This experiment was conducted to observe the characteristics of an L-band erbium-doped amplifier (EDFA) to study the gain and noise figure performances under limited pumping power. For this particular experiment, an erbium-doped fiber (EDF) of 12 meters length with an absorption coefficient of 34 dB/m at 1530 nm, an absorption coefficient of 12 dB/m at 1480 nm, a cut-off wavelength at 1400 nm and a numerical aperture of 0.21 was utilized as the amplification medium. An input signal of 1569 nm was supplied by a tunable laser source (TLS) and its power was fixed at -20 dBm and -25 dBm. A 1455 nm laser source was pumped into the erbium-doped fiber through a wavelength selective filter (W1) as shown in figure 1. A second wavelength selective filter (W2) was connected to the end of the erbium-doped fiber to separate the pump light from the sought amplified L-band output. The results obtained from the experiment showed that the gain started to saturate after 52.9 mW pump power for both input signals of -20 dBm and -25 dBm. The gain coefficient was also calculated from the outcome and from our findings; the pump power of 52.9 mW produced the highest gain coefficient values of 0.360 dB/mW for -20 dBm input and 0.364 dB/mW for -25 dBm input

Visual Communication in Sustainability Action: Public understanding through human behavior and attitude

The study aims to explore the essential elements of an idea in designing visual marketing, advertising, or design developments to impose sustainable efforts. The final data is distributed into four categories: Behavior and Attitude in Visual Development, Mechanism in Public Information, Process of Public Understanding, and Public Understanding in Visual Sustainability. The research suggests creators of visual communications consider how their work shapes attitudes and behaviours about sustainability. With awareness around information, public understanding, and connections between visual media and sustainability, designers can promote responsible, eco-conscious messages. This framework proposes the development process should cultivate mindfulness about communicating sustainability effectively

Optimization of hybrid Raman-Brillouin-EDF amplification fiber laser in long distance FBG sensor system

We present a hybrid Raman-Brillouin-Erbium Doped Fiber (EDF) amplification based Fiber Bragg Grating (FBG) sensor system capable of transmitting over long reach Single Mode Fiber (SMF). The performance of output spectra has been optimized and realized by the best effective placement of EDF and Raman pump power. An optimized combination of Raman, Brillouin and Erbium gain brings forth an optical signal-to-noise ratio of 16.34 dB in 100 km long distance FBG sensor system

Scalable heterogeneous nodes deployment algorithm for monitoring of underwater pipeline

Underwater Wireless Linear Sensor Networks (UW-LSNs) possess unique features as compared to the terrestrial sensor networks for pipeline monitoring. Other than long propagation delays for long range underwater pipelines and high error probability, homogeneous node deployment also makes it harder to detect and locate the pipeline leakage efficiently. Determining the exact leakage position with minimum delay stays a major issue where pipelines length is extremely long and expensive to deploy many underwater sensors. In order to tackle the problem of large scale pipeline monitoring and unreliable underwater link quality, many algorithms have been proposed and even some of them provided good solutions for these issues but the scalable nodes deployments still need focus and prime attention. In order to handle the problem of nodes deployment, we therefore propose a dynamic nodes deployment algorithm where every node in the network is assigned location in a quick and efficient way without needing any localization scheme. It provides an option to handle the heterogeneous types of nodes, distribute topology and mechanism in which new nodes are easily added to the network without affecting the existing network performance. The proposed distributed topology algorithm divides the pipeline length into segments and sub-segments in order to manage the higher delay issue. Normally nodes are randomly deployed for the long range underwater pipeline inspection yet it requires some proper dynamic nodes deployment algorithm assigning unique position to each nod