Integrated fiber-based transverse mode converter

A transverse mode converter based on a binary microrelief implemented directly on the end-face of a few-mode fiber was numerically investigated. The results of numerical simulation demonstrated the converter to form LP-11 and LP-21 modes with high efficiency, providing a more-than 92 % mode purity. Transformations of modes excited by a fiber microbending were also numerically investigated. The excited beams were shown to save their mode purity even in a strong bending as the arising parasitical modes were mostly unguided by the fiber. The resulting beam power and mode content were also demonstrated to depend on the beam and bending mutual orientation for beams with strong rotational symmetry.This work was partly supported by the Ministry of Education and Science of the Russian Federation (project 16.7894.2017/6.7)

Synthesis of silicon nanowires using plasma chemical etching process for solar cell applications

Recently, research on silicon nanowire solar cells has been developed rapidly and is one of the very young research field. The production of highly oriented long silicon nanowires is an challenging problem. Here, in this article we report the optimization of successful synthesis of highly oriented, long silicon nanowires on silicon substrates by plasma chemical etching process. The produced silicon structures were first examined using scanning electron microscopy (SEM). The SEM results clearly shows the highly oriented nanowires on the silicon substrate. The flowing carrier gas, temperature, pressure and voltage are main parameters responsible for the formation of the silicon nanowires. The successful synthesis of silicon nanowires shows bright perspectives for further research on silicon nanostructure properties

Theoretical study of the photoconductivity mechanism of the structure “carbon nanotubes – silicon substrate”

The types of optical radiation photodetectors have been considered according to the operating principle. The photoconductivity mechanism of carbon nanotubes (CNTs) deposited on a silicon substrate has been investigated theoretically. A comparison of the CNTs band gap with illuminating beam the quantum energy has been conducted. The heating and cooling cycles under the influence of a distributed surface energy source have been simulated. It has been established that CNTs on a silicon substrate have thermal-type photoconductivity. The sensitive element of the IR sensor based on this structure can be classified as a bolometric type

Sensitive element of CNT-based IR-sensor

A literature review of the works presenting the results of CNT studies as optical range radiation sensors has been provided. In principle, the possibility of using a CNT sample as a sensitive element for detecting IR radiation has been shown. The dependence of the CNT sample resistance on the CO2-laser radiation intensity has been determined.This work was supported by the Federal Agency of Scientific Organizations (agreement No 007-GЗ/Ch3363/26) and has been carried out within the framework of the strategic academic unit ‘Nanophotonics, emerging technologies of remote sensing and intellectual geoinformation systems’ of the Samara National Research University’s competitiveness improving program.The sensor investigation was partly supported by the Ministry of Education and Science project No. 16.7894.2017.6.7

Design and simulation of a SOI based mems differential accelerometer

In this paper, the design and analysis of a differential MEMS capacitive accelerometer is presented. The device is designed to be compatible for SOI based fabrication process. The outstanding mechanical and electrical properties of silicon on insulator (SOI) wafers make it popular for high-performance MEMS sensors such as accelerometers. The operating range of the designed device is 0-10g with its sense axis in the in-plane direction. The movable comb fingers attached to the proof mass form capacitors with the fixed electrode fingers. The movable and fixed fingers are spaced with unequal gaps to form the differential capacitive sensing configuration. The base capacitance of this configuration is about 0.77pF and the sensitivity in response to acceleration input is about 0.776 fF/g. The resonance frequency of the structure in the sensing mode is found to be 7.138 kHz.The work was partially funded by the Russian Federation Ministry of Education and Science

Design, simulation and fabrication process of a SOI based 2-DOF vibratory gyroscope

This paper reports the design, simulation and fabrication process for a 2-DOF decoupled vibratory gyroscope. The structure is deliberately designed to have decoupled drive and sense mode oscillation to prevent unstable operation due to mechanical coupling, resulting in low zero rate out-put drift. At the same time, the closer the drive and sense resonances are, the higher is the angular rate resolution of the gyroscope. This can be achieved by using symmetric suspensions, but it results in reduced bandwidth. The proposed design has been configured to achieve about 150 Hz bandwidth, while ensuring decoupled operation of the drive and sense modes. Fem analysis has been carried out in CoventorWare® MEMS DESIGN software and simulation results show that the drive resonance occurs at 21.48 kHz and sense resonance at 21.63 kHz. The structure is designed for 15 µm this device layer. Fabrication of the design is proposed using DRIE and sacrificial release etching on SOI wafer. DRIE etching with high aspect ratio has been successfully carried out as desired and the results have been presented

Optimization of parameters of binary phase axicons for the generation of terahertz vortex surface plasmon polaritons on cylindrical conductors

Рассмотрена возможность генерации поверхностных плазмон-поляритонов с орбитальным угловым моментом («закрученных плазмонов») на цилиндрических проводниках дифракционным методом ("end-fire coupling technique") в спектральном диапазоне от 8,5 до 141 мкм (~2 – 40 ТГц). Торец цилиндра освещается Бесселевыми пучками, сформированными с помощью бинарных спиральных фазовых аксиконов, или кольцевыми закрученными пучками, сформированными в фокальной плоскости дополнительной линзы. Построены графики, определяющие связь между параметрами волновода (диаметр проводника, равный диаметру освещающего пучка, и угол «закрутки» плазмона) и параметрами аксикона (отношение периода аксикона к длине волны излучения) для указанных выше длин волн и топологических зарядов пучков от 1 до 9. Полученные результаты свидетельствуют о возможности проведения в длинноволновом диапазоне экспериментов по моделированию плазмонного мультиплексного канала связи. The feasibility of generating surface plasmon polaritons carrying orbital angular momentum ("vortex plasmons") on cylindrical conductors by an end-fire coupling technique in the spectral range from 8.5 to 141 μm (~ 2-40 THz) is considered. The front face of the cylinder is illuminated by Bessel beams formed using binary spiral phase axicons, or annual vortex beams formed in the focal plane of an additional lens. Graphs are constructed that reveal the relationship between the waveguide parameters (conductor diameter, which is equal to the diameter of the illuminating beam, and the “twist” angle of the plasmon) and the axicon parameters (the ratio of the axicon period to the radiation wavelength) for the above wavelengths and topological charges of the beams ranging from 1 to 9. The results obtained indicate the possibility of conducting experiments in the long-wavelength range for modeling a plasmon multiplex communication channel.Работа выполнена при поддержке гранта РНФ 19-12-00103. При выборе расчётных параметров использованы результаты экспериментов, выполненных в ИЯФ СО РАН с использованием оборудования ЦКП «СЦСТИ» на базе УНУ «Новосибирский ЛСЭ»