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• Nickel-based metal organic framework (MOF) is used as a nonlinear material. • Nickel-based MOF/polydimethylsiloxane composite is spin-coated on a tapered fiber. • Encapsulation of the composite promotes better protection of tapered fiber waist. • The fabricated laser generates a fundamental soliton with good stability. This work demonstrates the fabrication of a saturable absorber with nickel 1,3,5-benzene-tricarboxylic acid (Ni-H 3 BTC)-metal organic framework (MOF) to generate soliton pulses in an erbium-doped fiber laser. The saturable absorber was fabricated by spin-coating Ni-H 3 BTC-MOF/polydimethylsiloxane composite on a tapered fiber as the encapsulation agent for light-matter interactions. The proposed cavity emitted a pulse laser at 1557.72 nm central wavelength with 3-dB bandwidth of 5.90 nm, pulse width of 907 fs, and average output power of 13.02 mW. At maximum pump power of 247.8 mW, the pulse energy was calculated to be 1.3 nJ at 10 MHz repetition rate. These results might assist as a footing to explore different types of available MOFs and their properties for the generation of ultrashort pulses. [ABSTRACT FROM AUTHOR]

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-H 3 BTC) using a spin-coating method. The fabricated Ni-H 3 BTC-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. [ABSTRACT FROM AUTHOR]

[Display omitted] • The modification of SPR chip using graphene oxide for the detection of dopamine is proposed. • Enhanced sensitivity of the developed plasmonic based sensor towards dopamine is demonstrated. • The sensor film showed high affinity to dopamine and real time sensorgrams were obtained in angular mode. • The developed sensor showed excellent reproducibility, repeatability, selectivity, and storage stability. • This sensor showed considerable promise as a reliable technique for fast detection at very low concentrations. The rapid and specific detection of dopamine (DA) is of great importance for diagnosis of neurodegenerative diseases. Surface plasmon resonance (SPR) sensors are promising tools for real time monitoring of biomolecular interactions. However, the sensitivity of such sensors necessitates improvement. For this purpose, graphene oxide (GO) was employed in this work to prepare the sensor chip. Interestingly, the proposed sensor possessed an excellent performance with high sensitivity of 0.2148°/pM and affinity constant of 2.148 TM−1. The precision for nine replicate detections of 100 fM was 0.125% (RSD). Significantly, this plasmonic based sensor has potential to determine DA in real time within 5 min. Moreover, it showed excellent reproducibility, repeatability, and selectivity to common interfering species, as well as outstanding storage stability. Considering its simple fabrication, high sensitivity and other sensing characteristics, it was found that this optical sensor showed considerable promise as a reliable technique for rapid detection and in-field measurement. [ABSTRACT FROM AUTHOR]

Thin films have infinite potential uses in optics and other fields. They must be well suited to meet the requirements of its specific application in terms of thickness, optical properties, morphology and other characteristics. Herein, surface plasmon resonance (SPR) technique was employed to accurately determine the thickness and analyze the optical characteristics of graphene oxide/gold (GO/Au) multilayered structure in contact with the neurotransmitter dopamine (DA). Based on the theoretical fitting of the experimentally recorded SPR dips, n and k values of GO layer were 1.4400 and 0.0250, respectively, prior to DA injection. By increasing DA concentrations, SPR experimental curves were shifted to higher angles continuously. DA Binding to SPR chip which was confirmed by AFM and FTIR analysis has increased both n and thickness of GO film while decreased k. These results proved sensitivity enhancement of the modified chip towards DA and highlighted the technique's appropriate and sufficient potential to measure thickness and refractive index variations in real-time when 100 fM of DA was detected with sensitivity of 12.402°/RIU. [ABSTRACT FROM AUTHOR]

The compositions of 3 wt.% trivalent erbium ions (Er3+) doped zinc silicate (Zn 2 SiO 4) glass-ceramics was fabricated from waste materials via conventional solid-state method. From the XRD and FESEM results designate that the diffraction peaks of 3 wt.%Er3+:Zn 2 SiO 4 glass-ceramics improved with the heat treatment progression and homogeneously distributed in hexagonal and rectangular shapes. From UV–vis measurement, three detected peaks of optical absorption that corresponding to the optical transitions of Er3+ ions are located at 492 nm (4F 7/2), 524 nm (2H 11/2), and 650 nm (4F 9/2). The intensive sharp characteristic emission that correlated with Er3+ luminescence is resolved in photoluminescence spectra at room temperature and gives a yellow-green light colour emission at 559 nm under 385 nm excitation peaks. [ABSTRACT FROM AUTHOR]

In this study, Mn 2+ -doped willemite glass-ceramics were prepared from conventional melt-quenching method derived MnO-ZnO-SLS precursor glass by an isothermal heat-treatment process where waste SLS glass bottle are used as a silicon source. The structure, phase morphology and luminescent properties of the Mn 2+ -doped willemite phosphors were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and photoluminescence (PL) spectroscopy. The XRD pattern revealed the phase transformation of zinc orthosilicate (α-Zn 2 SiO 4 ) with the progression of heat treatment temperature. The FESEM images showed the aggregated and irregularity in shape morphology of the samples. Meanwhile, the emission intensity of the samples exhibit a green emission centered at about 527 nm while the yellow emission centered at 585 nm and red emission centered at 600 nm resulted from 4 T 1 – 6 A 1 energy transition of Mn 2+ ions, respectively. [ABSTRACT FROM AUTHOR]

• A simple and cost-effective technique for mercury ion (Hg2+) detection is proposed. • The technique based on the incorporation of SPR spectroscopy with novel thin film. • The thin film is nanocrystalline cellulose/poly(3,4-ethylenedioxythiophene) (NCC/PEDOT). • This study proved that NCC/PEDOT can enhance the sensitivity of SPR for Hg+. • As low as 2 ppb of Hg2+ can be detected using NCC/PEDOT based SPR spectroscopy. In order to enhance the sensing performance and the sensitivity of surface plasmon resonance (SPR) sensor, a potential sensing layer should be immobilized on a metal thin film. Thus, the immobilization of nanocrystalline cellulose/poly(3,4-ethylenedioxythiophene) (NCC/PEDOT) on gold thin film has been fabricated for mercury ion (Hg2+) detection. Then, the sensing layer thin film has been incorporated with SPR spectroscopy and the SPR reflectivity signal was observed for the interaction between NCC/PEDOT thin film and different concentrations of Hg2+ solution (2–100 ppb). From the obtained SPR signal, important parameters investigated have proven the performance of the sensor. To be highlighted, the sensitivity for NCC/PEDOT-based SPR sensor was 48.5193° ppm−1 for lower concentration of Hg2+. Additionally, the binding affinity constant was calculated by using the Langmuir isotherm model. Therefore, the results displayed the potential sensing of NCC/PEDOT based sensor for mercury ion detection, as the limit of detection was 2 ppb. [ABSTRACT FROM AUTHOR]