This work demonstrates a simple and economical route of preparing molybdenum trioxide/polydimethylsiloxane composite saturable absorber (MoO3-SA) for ultrashort pulse generation. The average size of MoO3 used in this work was about 10 μm and conveniently prepared using standard bath sonication. The MoO3-SA was fabricated by depositing MoO3 composite on tapered microfiber structure of 10 μm waist diameter via spin coating technique. The modulation depth, saturation fluence and non-saturable loss of the fabricated MoO3-SA were measured to be 4.02%, 28.3 μJ/cm2 and 33.02%, respectively. The employment of the MoO3-SA in erbium-doped fiber laser was able to generate mode-locked pulses at a threshold pump power of 64.1 mW with a central wavelength of 1559.87 nm and an ultrashort pulse duration of 748 fs. Micrometer-sized materials are far simpler in preparation which relaxes tight requirements for SA fabrication compared to advanced nanomaterials.

We experimentally demonstrate the generation of noise-like pulse (NLP) in an erbium-doped fiber laser using a metal-organic framework (MOF)-based saturable absorber. To fabricate the device, a tapered fiber was coated with MOF material, nickel 1,3,5-benzene-tricarboxylic acid (Ni-H3BTC) using a spin-coating method. The fabricated Ni-H3BTC-MOF saturable absorber exhibited 4.5% modulation depth and 30.3 MW/cm2 saturation intensity. A mode-locked erbium-doped fiber laser operated in the NLP regime was successfully achieved at 1564.90 nm central wavelength having 3-dB bandwidth of 19.96 nm, repetition rate of 9.02 MHz, and signal-to-noise ratio of 57.17 dB at 248 mW pump power. The characteristics of the NLP was confirmed by the spike width of 148 fs riding on a pedestal pulse duration of 26.67 ps. The estimated value of its damage threshold was experimented to be beyond 4.69 GW/cm2. These results infer that MOF-based saturable absorber can be an alternative material for the generation of ultrashort pulses.

A tapered microfiber decorated with titanium dioxide-silicon dioxide nanocomposite saturable absorber (TiO2-SiO2-SA) is demonstrated via alkali fusion method and spin-coating technique. The TiO2-SiO2-SA exhibited 17.1% modulation depth, 31.7 µJ/cm2 saturation fluence and 35.4% non-saturable loss. The TiO2-SiO2-SA was able to generate a pulse duration of 797 fs at a repetition rate of 10.39 MHz and an average output power of 16.57 mW at 1.56 μm. This work presents an enhanced pulse duration within titanium-based saturable absorbers. The high damage threshold of beyond 24.82 GW/cm2 and excellent stability are believed to have opened a new route of using nanomaterials derived from waste product for next generation ultrafast photonic applications.

In this work, we have demonstrated the generation of dissipative soliton from single to multi-pulsing phenomenon. The generation of ultrashort pulses was achieved with nickel-based metal organic framework (Ni-MOF) as saturable absorber in a ring cavity erbium-doped fiber laser. The SA was fabricated by spin-coating Ni-MOF/polydimethylsiloxane composite on a tapered fiber substrate, which had an insertion loss of 2.82 dB, a modulation depth of 4.61 %, and saturation intensity of 30.12 MW/cm2. A self-started DS mode-locked pulse was observed at 1559.89 nm central wavelength with 3-dB bandwidth of 19.72 nm at threshold pump power of 33.5 mW. Its pulse width of 7.89 ps was recorded at 7.94 MHz repetition rate. The nature of pulse splitting was observed up to three pulses which were separated with 2.62 ns time spacing with the increment of pump power until 134.2 mW. The generated multiple dissipative soliton pulses realized in the laser cavity through Ni-MOF saturable absorber were stable and invariant for 1-hour stability measurement.

This investigation demonstrates the nonlinear saturable absorption of cerium oxide (CeO2) nanoparticles; a lanthanide allotrope oxide material and its employment as a saturable absorber (SA) for the generation of stable mode-locked pulsed fiber laser. The CeO2 nanoparticles were simply prepared by sonicating its bulk solution and incorporating a polydimethylsiloxane (PDMS) polymer to form a thin film nanocomposite on tapered optical fiber for the fabrication of CeO2/PDMS-SA. The nonlinear intensity-dependent transmission characteristic of this material was confirmed with a modulation depth of 0.66% and saturation intensity of 77 MW/cm2. The SA was integrated into an erbium-doped fiber laser cavity, where mode-locking operation self-started at 35 mW pump power with stable soliton operation up to 250 mW in net anomalous dispersion regime. The pulse laser centered at 1561 nm

The envelope glycoprotein domain III (EDIII) of dengue virus (DENV) has been recognised as the antigenic region responsible for receptor binding. In the present work, we have proposed a novel immunosensor constructed on a graphene-coated screen-printed carbon electrode (SPCE) using plant-derived EDIII as the probe antigen to target DENV IgG antibodies. The developed immunosensor demonstrated high sensitivity towards DENV IgG within a wide linear working range (125–2000 ng mL−1) under the optimised sensing conditions. The limit of detection was determined to be 22.5 ng mL−1. The immunosensor also showed high specificity towards DENV IgG, capable of differentiating DENV IgG from the antibodies of other infectious diseases including the similarly structured Zika virus (ZIKV). The ability of the immunosensor to detect dengue antibodies in serum samples was also verified by conducting tests on mouse serum samples. The proposed immunosensor was able to provide a binary (positive/negative) response towards the serum samples comparable to the conventional enzyme-linked immunosorbent assay (ELISA), indicating promising potential for realistic applications.

This paper presents a finite volume-based simulation study on the effect of the fin valley's number on the thermal performance of a bus duct conductor. A numerical model that closely mimics the experimental setup was developed using ANSYS FLUENT. The experimental data were used as a benchmark and followed the IEC 61439-1/2 standards. Five fin valley numbers were considered: s1=2, s2=3, s3=4, s4=5 and s5=6. It was determined that the average surface temperature decreased as the number of fin valleys increased. From the analysis, it was observed that as the number of fin valleys increased, convection heat transfer improved as a consequence of enhanced surface Nusselt number. The best number of fin valleys was s5=6, exhibiting superior thermal performance over a lower number of fin valleys. This study is expected to provide a better understanding of the fin valley’s effects on the thermal performance of a bus duct conductor’s casing.

This paper studies the fin thickness variation effect on a bus duct conductor’s thermal performance and the nanocomposite coating method selection for the bus duct conductor’s heat sink. ANSYS FLUENT was used to create a numerical model resembling the experimental setup. The IEC 60439-1 and IEC 60439-2 standards were used to benchmark the experimental data. The results revealed that the “chimney effect” induces an increment of the hot air adjacent to the heat sink. A conspicuous increase in the total heat transfer rate and fin effectiveness was observed as the fin thickness was reduced. This study revealed that s1 = 1 mm was the best fin thickness with 1.254 fin effectiveness, 1.862 W of total heat transfer rate, and 17.5 Nusselt number. Additionally, various coating methods were examined experimentally to select the best nanocomposite coating for the bus duct conductor’s heat sink. The ultrasonic agitation was the best coating method, which resulted in the lowest average resistance (8.8 μΩ) and a better percentage of Ag (0.6%–2.5%) on the substrate surface. Thus, the current outcomes are expected to better comprehend the impact of fin thickness on thermal performance, as well as the selection of coating method for the bus duct conductor.