Optical-Fiber Microsphere-Based Temperature Sensors with ZnO ALD Coating—Comparative Study

This study presents the microsphere-based fiber-optic sensor with the ZnO Atomic Layer Deposition coating thickness of 100 nm and 200 nm for temperature measurements. Metrological properties of the sensor were investigated over the temperature range from 100 °C to 300 °C, with a 10 °C step. The interferometric signal was used to monitor the integrity of the microsphere and its attachment to the connecting fiber. For the sensor with a 100 nm coating, a spectrum shift of the reflected signal and the optical power of the reflected signal were used to measure temperature, while only the optical power of the reflected signal was used in the sensor with a 200 nm coating. The R2 coefficient of the discussed sensors indicates a linear fit of over 0.99 to the obtained data. The sensitivity of the sensors, investigated in this study, equals 103.5 nW/°C and 19 pm/°C or 11.4 nW/°C for ZnO thickness of 200 nm and 100 nm, respectively.

Excitation of Multi-Beam Interference and Whispering-Gallery Mode in Silica Taper-Assisted Polymer Microspheres for Refractometric Sensing

We propose and numerically analyze a fiber-optic sensor based on a silica taper-assisted multiple polymer microspheres to realize high-sensitivity refractometric sensing due to the excitation of multi-beam interference and whispering-gallery modes (WGMs) in each microsphere. Up to 5 UV-cured adhesive microspheres are dripped in sequence on the 2 µm-diameter silica taper with the certain distances in between. Scattering and reflection of light in each microsphere enhance the multi-beam interference because of the emergence of high-order modes. Moreover, WGMs with certain resonant wavelengths are excited in the microspheres, further enhancing the transmission spectrum with high contrast and quality factor. Furthermore, irregular transmission spectrum corresponds to the large wavelength tuning range. Propagating light between the microspheres could be strongly affected by the environmental factor with the large transmission spectrum shift, therefore realizing the refractometric sensing with high sensitivity of 846 nm/RIU based on the taper-assisted 2-spheres sensor. Furthermore, another two microspheres are placed on both sides of 2-spheres sensor to form 4-spheres-loop sensor, re-collecting those large-angle scattering light with the enhancement of multi-beam interference and WGMs. Therefore, the sensitivity of 4-shperes-loop sensor is further improved to the maximum of 1296.3 nm/RIU.

Temperature Fiber-Optic Sensor with ZnO ALD Coating

This study presents a microsphere-based fiber-optic sensor with a ZnO Atomic Layer Deposition (ALD) coating thickness of 100 nm for temperature measurements. Metrological properties of the sensor were investigated over the temperature range of 100 °C to 300 °C, with a 10 °C step. An interferometric signal is used to control whether the microstructure is whole. Spectrum shift of a reflected signal is used to ascertain changes in the measured parameter. With changing temperature, the peak position of a reflected signal also changes. The R2 coefficient of the presented sensor indicates a good linear fit of over 0.99 to the obtained data. The sensitivity of the sensor investigated in this study equals 0.019 nm/°C.

Optimization of the ZnO ALD Coating of a Photonic Microsphere-Based Temperature Sensor

This study presents of the microsphere-based fiber-optic sensor with the ZnO ALD coating thickness of 100 nm and 200 nm for temperature measurements. Metrological properties of the sensor were investigated over the temperature range of 100°C to 300°C, with a 10°C step. The interferometric signal is used to control whether the microstructure is intact. Spectrum shift of a reflected signal is used to conclude changes in measured parameter for the sensor with a 100 nm coating, while the reflected signal intensity is an indicator during measurements executed by a sensor with a 200 nm coating. With changing temperature, the peak position or intensity of a reflected signal also changes. The R2 coefficient of the presented sensors indicates a linear fit of over 0.99 to the obtained data. The sensitivity of the sensors, investigated in this study, equals 103.5 nW/°C and 0.019 nm/°C for ZnO thickness of 200 nm and 100 nm, respectively.

Synthesis and Characterization of Silica-Lead Sulfide Core Shell Nanospheres For Applications in Optoelectronic Devices

Nanoscale miniaturization of chalcogenides semiconductors, such as lead sulfide (galena), can generate interesting quantum confinement effects in the field of optoelectronic applications. At this work, a process in order to obtain SiO2 nanospheres coated with Galena, as the denominated core-shell system, is developed, this process it is based in Stöber’s method, where only the magnetic stirring was replaced by an ultrasonic bath, to achieve well rounded, and highly stable silica nanoparticles with diameters average of 70 nm. The PbS shell cover presents a thickness of 10 nm around. Nanostructures chemical composition, morphology and optical properties were determined by Transmission Electron Microscopy and UV-Vis spectroscopy, respectively. As a result, the nano shells correspond to cubic PbS, presenting some interplanar distances of 2.95 Å and 3.41 Å; this nano shell also shown a toward blue optical spectrum shift and a remarkable increase in its band gap, 3.75 eV, was obtained, compared with the PbS bulk value. The chemical composition it is studied by energy scattering spectroscopy, and X-ray photoelectron spectroscopy analyzes.

PEMANFAATAN GESERAN POLA SPEKTRUM UV SENYAWA GOLONGAN BARBITURAT DALAM UJI KONFIRMASI DENGAN METODE TLC-SPEKTROFOTODENSITOMETRI

A Research of the utilization of spectrum shift in confirmation test for barbiturate using TLC-Spectrophotodensitometry has been done. Analyte was analyzed using two mobile phases, that are TD (chloroform: acetone = 80 : 20) and TE (ethyl acetate: methanol: ammonia = 85 : 15 : 5) with Al-TLC Silica 60 GF254 plate as the stationary phase. Afterwards, plate was sprayed with HCl or KOH. The analyzed parameters were hRfc, normal UV-spectrum pattern and its shift. The correlation of spectrum or the shift of UV-spectrum for barbiturate compounds was determined with Wincats program. The analysis of barbiturates which based on hRfc in error window (±7) for TD system and in error window (±11) for TE, still produced hit factor 8-25 compounds. The confirmation test for barbiturates based on hRfc and r ? 0,95, produced hit factor 1-2 compounds. Barbiturate compounds showed spectrum shift in alkali solution, while in acid solution did not happen. However, all four analytes contained identical spectrum shift, therefore the data of these spectrum shift can not be utilized for confirmation test of barbiturate compounds.