Temperature Sensing Using Colloidal-Core Photonic Crystal Fiber

We report on a temperature sensor based on the monitoring of the luminescence spectrum of CdSe/ZnS nanocrystals, dispersed in mineral oil and inserted into the core of a photonic crystal fiber. The high overlap between the pump light and the nanocrystals as well as the luminescence guiding provided by the fiber geometry resulted in relatively high luminescence powers and improved optical signal-to-noise ratio (OSNR). Also, both core end interfaces were sealed so as to generate a more stable and robust waveguide structure. Temperature sensitivity experiments indicated a 70 pm/degrees C spectral shift over the 5 degrees C to 90 degrees C range

Optical Fiber Sensors Based on Nanoparticle-Embedded Coatings

The use of nanoparticles (NPs) in scientific applications has attracted the attention of many researchers in the last few years. The use of NPs can help researchers to tune the physical characteristics of the sensing coating (thickness, roughness, specific area, refractive index, etc.) leading to enhanced sensors with response time or sensitivity better than traditional sensing coatings. Additionally, NPs also offer other special properties that depend on their nanometric size, and this is also a source of new sensing applications. This review focuses on the current status of research in the use of NPs within coatings in optical fiber sensing. Most used sensing principles in fiber optics are briefly described and classified into several groups: absorbance-based sensors, interferometric sensors, fluorescence-based sensors, fiber grating sensors, and resonance-based sensors, among others. For each sensor group, specific examples of the utilization of NP-embedded coatings in their sensing structure are reported

Fluorescence of CdSe/ZnS Quantum Dots in Toluene: Effect of Cyclic Temperature

Quantum dots (QDs) are the potential material for the application in optical thermometry, and have been successfully applied to solar cells, LEDs, bio-labeling, structural health monitoring, etc. In this paper, we study the fluorescence properties of CdSe/ZnS QDs in toluene under the action of heating-cooling cycles. The experimental results show that, in a heating-cooling cycle, increasing temperature causes red-shift of the emission peak and the decrease of the PL intensity, and decreasing temperature causes blue-shift of the emission peak and the increase of the PL intensity. The surface structures of the QDs likely are dependent on the cycle numbers, which cause the change of the excited energy state of the QDs in toluene. The results presented in this paper reveals the strong effects of cyclic temperature on the photoluminescence characteristics of QDs

Photonic crystal fibers for sensing applications

Photonic crystal fibers are a kind of fiber optics that present a diversity of new and improved features beyond what conventional optical fibers can offer. Due to their unique geometric structure, photonic crystal fibers present special properties and capabilities that lead to an outstanding potential forsensing applications. A review of photonic crystal fiber sensors is presented. Two different groups of sensors are detailed separately: physical and biochemical sensors, based on the sensor measured parameter. Several sensors have been reported until the date, and more are expected to be developed due to the remarkable characteristics such fibers can offer.The authors are grateful to the Spanish Government project TEC2010-20224-C02-01

Estudio de fibras de cristal fotónico para biosensado haciendo uso de interrogación transversal

[ES] Las fibras de cristal fotónico (es decir, perforadas longitudinalmente por un array periódico de micro-agujeros) han cobrado un gran interés recientemente, ya que sus propiedades son muy prometedoras para aplicaciones que van desde fenómenos no lineales hasta sensado de líquidos y gases. En ese último caso, el hecho de que los agujeros de la fibra puedan ser infiltrados con ciertas sustancias es lo que le confiere la relevancia para aplicación en bio-sensado. En general, el sensado se produce inyectando y detectando luz en la dirección longitudinal, lo que hace que los dispositivos aunque eficientes sean de mucha longitud. Sin embargo, las propiedades de periodicidad de la fibra permiten también que esta pueda interaccionar fuertemente con la luz inyectada en la dirección transversal. De hecho, la periodicidad debe producir bandas de propagación prohibidas cuyas frecuencias variarán enormemente con la infiltración de gases o líquidos, por lo que se podría realizar bio-sensado en una distancia mucho menor que en el caso de la inyección de luz en la dirección longitudinal. En este TFG se propone explorar esta alternativa como una nueva vía de bio-sensado fotónico.Collantes Pablo, G. (2017). Estudio de fibras de cristal fotónico para biosensado haciendo uso de interrogación transversal. http://hdl.handle.net/10251/87009.TFG

Ionizing Radiation Detection Using Microstructured Optical Fiber

Ionizing radiation detecting microstructured optical fibers are fabricated, modeled and experimentally measured for X-ray detection in the 10-40 keV energy range. These fibers operate by containing a scintillator material which emits visible light when exposed to ionizing radiation. An X-ray source characterized with a CdTe spectrometer is used to quantify the X-ray detection efficiency of the fibers. The solid state CdTe detector is considered 100% efficient in this energy range. A liquid filled microstructured optical fiber (MOF) is presented where numerical analysis and experimental observation leads to a geometric theory of photon transmission using total internal reflection. The model relates the quantity and energy of absorbed X-rays to transmitted and measured visible light photons. Experimental measurement of MOF photon counts show good quantitative agreement with calculated theoretical values. This work is extended to a solid organic scintillator, anthracene, which shows improved light output due to its material properties. A detailed description of the experimental approach used to fabricate anthracene MOF is presented. The fabrication technique uses a modified Bridgman-Stockbarger crystal growth technique to grow anthracene single crystals inside MOF. The anthracene grown in the MOF is characterized using spectrophotometry, Raman spectroscopy, and X-ray diffraction. These results show the anthracene grown is a high purity crystal with a structure similar to anthracene grown from the liquid, vapor and melt techniques. The X-ray measurement technique uses the same approach as that for liquid filled MOF for efficiency comparison. A specific fiber configuration associated with the crystal growth allows an order of magnitude improvement in X-ray detection efficiency. The effect of thin film external coatings on the measured efficiency is presented and related to the fiber optics. Lastly, inorganic alkali halide scintillator materials of CsI(Tl), CsI(Na), and NaI(Tl) are grown as single crystals inside the MOF. These alkali halide fibers show an improvement in X-ray detection efficiency comparable with the CdTe detector and can be more efficient, dependent upon the photon counter efficiency and fiber configuration. The fiber configuration for this improved efficiency is described as the same for the higher efficiency anthracene MOF

Нанорозмірні гранульовані системи як елементи мікроелектроніки і сенсоріки

Мета кваліфікаційної роботи бакалавра полягає в огляді сучасних нанорозмірних гранульованих систем як елементів мікроелектроніки і сенсоріки. Під час виконання роботи використовували аналіз сучасних літературних джерел та інтернет ресурсів, присвячених новим методам та технологіям конструювання елементів електроніки та сенсоріки на основі нанорозмірних гранульованих систем. У результаті проведеного літературного аналізу визначено методи одержання нанорозмірних гранульованих систем та їх основні властивості. Ця інформація наводиться в першому розділі. Другий розділ присвячений огляду елементів електроніки: резисторів, перемикачів, транзисторів, а в третьому розглянуто характеристики та будову сенсорів на основі нанорозмірних гранульованих систем