summary (Исследование оптического диэлектрического микрорезонатора для детектирования наночастиц)

1NATIONAL RESEARCH UNIVERSITY HIGHER SCHOOL OF ECONOMICSTHE ALL-RUSSIAN RESEARCH INSTITUTE FOR OPTICAL ANDPHYSICAL MEASUREMENTS FEDERAL STATE UNITARY ENTERPRISEMIN’KOV KIRILL NIKOLAEVICHRESEARCH OF OPTICAL DIELECTRICMICROCAVITIES FOR DETECTING NANOPARTICLESSUMMARY OF DISSERTATIONFor the PhD HSEScientific supervisor:PhD, Associate ProfessorYurin Alexander IgorevichMoscow — 20182GENERAL CHARACTERISTICSProblem statementThe issue of monitoring solid particles availability including nanoparticles inclean gas medium is critical in a large number of application areas from providingnon-hazardous atmosphere for breathing of people including breathing duringouter-space flights and to atmosphere control inside lithography machinesmanufacturing large-scale integration microcircuits with nano-sized elements.

Inthe latter case, to exclude rejected material the issue is even about single particles.Under the conditions of digital transformation of economic branch, plants ofthe future engineering and transition to Industrial Internet of Things there is a needto create not just high-sensitivity sensors but inexpensive, compact, needing nosetting and maintenance ones.

And if such a problem is solved for the largeparticles (>0,5 µm) on the ground of diffusion recording, then the solution for thenanosized particle range has not been found yet.Existing devices for monitoring nanoparticles concentration are not sensitiveto single nanoparticles, require difficult sample preparation, they are unhandy andexpensive. A highly qualified operator is needed to work with such device.Using the methods of nanoparticles recording based on the appliance ofdielectric optical microcavities (DOM) allows creating sensors that meet therequirements of digital economy applicable to measuring systems.Status and degree of development of the problemAt the moment a great number of research teams are studying the issue ofnanoparticles detecting by the means of DOM.

The team from the University ofWisconsin-Madison (USA) shows the possibility of detecting nanotubes ofdifferent sizes using facility assembled as a part of an electronic microscope. In itsstudies the team uses lithographic resonators with a Q-factor of 106 as well as themethod of detecting a signal by frequency shift. The team from the Max Planck3Institute for the Science of Light, Germany, is one of the leaders in this field. Intheir research the team investigates biological objects in fluid.

Great attentionshould be paid to their research on comparing sensibility indices of differentdetecting methods of objects of different sizes. Another interesting research teamfrom Center for Photonics Technology, USA, made an attempt to detectnanoparticles in the air medium using cylindrical glass cavities. However the Qfactor is relatively low - 106 and therefore the sensitivity is far from great.Purpose and objectives of researchThe purpose of the study is to improve methods and monitoring facilitiesfor nanoparticles concentration using dielectric optical microcavities.To archive this purpose a number of objectives were set, among these are:1. To study the methods of DOM manufacturing;2. To study factors affecting the DOM metrologicalcharacteristics during manufacturing process;3.

To study the influence of DOM internal inhomogeneities onits metrological characteristics;4. To study and develop optical communications methods whichensure the maximum Q-factor of DOM;5. To study and analyse monitoring methods of nanoparticlenumber concentration in air medium;6. To develop creation methods of nanoparticle numberconcentration for determining the metrological characteristics of thesensor based on DOM in air medium;7. To study and develop methods for improving DOMsensibility in interaction with nanoparticles in a liquid medium.4Relevance of the studyAt the present time DOM is widely used in science and technology. DOMis a high-quality selective element, which is an analog of a high-quality circuitor microwave resonator, having a narrow resonance curve the possibility oftuning in frequency and resistant to interference.

They are used as frequencyfilters in which the tuning can be carried out due to mechanical compression orstretching and also due to a change in temperature. DOM allow to realize highfrequency signal generators with small phase noise. The literature describes thepossibility of combining several microresonators in different configurations offine line filters, the theoretical transmission width of the amplitude-frequencycharacteristic of such a filter is unlimited.

Also multistage filters with a carryingcapacity up to 100 GHz are manufactured on the basis of DOM.In Jet Propulsion Laboratory, Pasadena, the USA uses DOM as part of anintegrated gyroscope in satellites and spacecrafts. Sensors based on DOM areable to measure temperatures from cryogenic to room temperature with aresolution of 10-6 K. DOM can be used as add-on devices for stabilizing lasers.Through the connection with the DOM the laser emission spectrum narrows andit also becomes possible to create tunable in frequency lasers.Resonators allow to create optical combs.

The use of detectors ofnanoparticles based on resonators is of particular interest because they arecapable to increase significantly the sensitivity limit of modern methods formeasuring the concentration of nanoparticles.Nanoparticles of various materials are widely used in manufacturing, inscience, and in medical research. Among them, the most common particles areAl2O3, TiO2, SiO2 and ZnO. Geometric dimensions, surface morphology, massand counting concentration and charge are most often studied parameters ofnanoparticles.One of the important objectives in studying of nanoparticles is detectingultra-small concentration of nanoparticles in different media.

This objective can beachieved with the help of great number of procedures which can be divided into5two groups: deterministic and probabilistic methods.Deterministic methodincludes scanning electron microscope, transmission electron microscopy, atomicforce microscopy, piezobalance dust monitor. Probabilistic methods includes staticlight scattering, dynamic light scattering, differential mobility analyzer andultrasound attenuation spectroscopy.Using the above methods in most cases allows the measurement of one ofthe above nanoparticles parameters. Also on the market there are no devices thatcan work both in air and water media, with the exception of microscopy, where it ispossible to do this through laborious preparation of the sample. Another significantdisadvantage of all the indicated methods is the inability to measure ultra-smallconcentrations of nanoparticles up to 5 nm in size.Another promising method is the use of optical diellectic microresonatorswith whispering gallery modes as detectors for nanoparticles.

The microcavity is abody of revolution with diameters from hundreds of nanometers to tens ofmicrometers.For the creation of DOM intended to nanoparticle detention two parametersare of particular importance: field confinement which determines the volumeactive region and Q-factor, which is directly proportional to the DOM sensitivity tothe minimum concentration of nanoparticles.Author’s personal contributionThe thesis contains the results of the work carried out by the author for 4years.

Personal contribution of the author to the thesis: ¶1) setting of the purpose and objectives of the study;2) analysis of literature and research methods;3) designing, collecting and debugging experimental installations;4) conducting experiments in full volume; ¶5) processing the results and formulating the findings of the study.6The practical value of the work is that on the basis of this study a prototypeDOM suitable for determining the concentration of nanoparticles in the air wascreated.

Acts of implementation and 2 patents were received.The work was supported by the Ministry of Education and Science of theRussian Federation in the framework of the implementation of the agreement No.14.625.21.0041 of September 26, 2017 (unique identifier of applied scientificresearch RFMEFI62517X0041)Research methodologyWe apply development methods of measuring instruments, empirical andstatistical methods of studying metrological characteristics to theoretical research.Processing of measuring signals was carried out in the software packagesMATLAB, WinPython, Origin.We apply method of scanning electron microscopy, method of transmissionelectronic microscopy, method of differential electric mobility, method of dynamiclight scattering, method of optical microscopy, method of confocal microscopy andmethod of interference microscopy to experimentation.Thesis statements for defending1.

The formation of a homogeneous thermal field by circular heating in thepresence of particles with a size of 0.5 μm and 1 μm and concentration to amaximum of 4 × 105 pc. and 8 × 104 pc. respectively ensures the production ofDOM with a deviation of a diameter not worse than 10% in the range from 160 μmto 1800 μm, deviation of the plane of the equator tangent from the axial line of theleg is not more than 2% and a Q-factor of 1 × 109±20%;2.