Персона: Козырев, Антон Андреевич
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Optoacoustic Effect in a Hybrid Multilayered Membrane Deposited on a Hollow-Core Microstructured Optical Waveguide
© Modern imaging technologies, including optoacoustic endoscopy, are based on the optoacoustic effect. Much promise is offered by the all-optical fiber-based approach, because fiber has a miniature cross section, is highly sensitive, and can be used in a variety of imaging and therapeutic techniques. We developed a probe based on a hollow-core microstructured optical waveguide (HC-MOW) with a hybrid nanostructured membrane. The membrane consisted of a free-standing single-walled carbon nanotube film and a Bragg reflector, which can be used as a source and a detector of ultrasound. Membrane vibrations were excited with an IR laser pulse and were read out by recording the intensity of the reflected visible CW laser light. We explained the nature of the intensity modulation of the reflected light and supported our explanation with numerical simulations of the membrane's vibration eigenfrequencies and thermal distribution. The membrane vibrations were also observed with raster-scanning optoacoustic mesoscopy. The transmittance of the HC-MOW between 400 nm and 6.5 μm and that of the hybrid nanostructured membrane in the NIR range enable potential optoacoustic sensing in the IR fingerprint region of biomolecules. This permits the optoacoustic probe to be used for medical endoscopic purposes.
Effect of the amount of argon in an oxygen ion beam on the optical characteristics of titanium dioxide films obtained via ion-assisted electron beam evaporation
© 2019 Optical Society of America.The effect of argon in a mixture with oxygen in an ion beam on the optical characteristics of titanium dioxide (TiO2) obtained via ion-assisted electron beam evaporation in vacuum was studied. It was shown that the addition of an inert gas at a level of 20%–25% resulted in an increase in the refractive index of the resulting TiO2 coating and a decrease in the sensitivity of the spectral characteristic of the coating to the effect of the atmosphere as a result of the decrease in the film porosity. The maximum amount of argon in the mixture was determined, amounting to 26%, at which the TiO2 film had an extinction coefficient not exceeding k = 0.0001.
Application of Upconversion Luminescence of NaYF4:Yb,Er Nanoparticles to Study Protein Coagulation Dynamics
© 2020, Pleiades Publishing, Ltd.Abstract: We present a method for measuring the dynamics of the internal temperature of biological tissues and the thickness of a denatured layer during laser thermolysis. This method is based on measuring the intensities of three luminescence bands of NaYF4:Yb,Er upconversion nanoparticles in the green and red parts of the visible spectrum. Ovalbumin was used as a model biological tissue, the general denaturation patterns of ovalbumin were also studied using plasmonic photothermal therapy.
Co-deposited Si-Al thin films as a base material to decrease the reflectance in the millimeter-band frequencies
© 2022 SPIE.Ongoing active development of modern radiofrequency electronic devices operating in the millimeter (V) band, such as 5th-generation wireless communications demands new materials to control electromagnetic interference, compatibility and reliability of such systems. Here we present a follow-up of studies on antireflective and absorptive micrometer-thick film coatings for operation in V-band using simultaneous magnetron co-deposition of silicon and aluminum. In this system graded segregation was observed under certain regimes, resulting in a depth gradient of aluminum content. Further investigations on the morphology of the obtained films were performed. Inhibition of electromagnetic waves reflection in 50-70 GHz range by up to 27 dB (at least 10 dB throughout the whole range) was achieved through variation of Al content in coatings by the ratio of sputtered atoms fluxes. Surface morphology of films as well as optical properties of those in visible and near IR bands were investigated. It was found that electrophysical properties of resulting samples are severely influenced by the amount and homogeneity of aluminum distribution in the coating. Optical spectroscopy suggests that variation of aluminum content in the film allows for control over resulting film material kind that can be adjusted from dielectric through semiconductive to almost metal-like. Non-homogeneous aluminum distribution in the depth of the film, particularly existence of a two-layered semiconductive optical structure in samples prepared at particular deposition regime was confirmed by measuring optical reflection spectra from the coating side and in reverse. Segregation of aluminum towards the surface of the film in course of silicon recrystallization was confirmed by AFM and surface roughness measurements.
Using the RGB data of bright-field optical microscopy to efficiently monitor the surface cleanliness of the active elements of semiconductor wafers in the planar production cycle
© 2020 Optical Society of AmericaIt is shown that it is promising to use the RGB data of bright-field optical microscopy to efficiently monitor the surface cleanliness of the active elements of semiconductor wafers in the planar production cycle. It is demonstrated that the film thickness on a substrate surface can be determined from RGB data obtained by means of a photosensor based on a Bayer array with known spectral response. An example shows how to use it on a GaAs semiconductor wafer with metallized active gold elements. Software has been developed for channel-by-channel comparison of a discriminated region of two pictures. An algorithm is presented for obtaining micrographs that can subsequently be analyzed and compared.
Improvement of the current - Voltage performance of broadened asymmetric waveguide InGaAs/AlGaAs/GaAs semiconductor lasers ( λ = 940 - 980 nm)
© 2022 Kvantovaya Elektronika and IOP Publishing Limited.The purpose of this work is to improve the current - voltage (I - V) performance of semiconductor lasers based on broadened asymmetric waveguide InGaAs/AlGaAs/GaAs separate-confinement double heterostructures. We analyse the effect of AlGaAs waveguide layer composition on the output characteristics of the lasers and demonstrate that the decrease in the series resistance of the lasers and the threshold voltage of their I - V characteristic as a result of a decrease in the percentage of AlAs in the waveguide layers shifts the drop in the differential quantum efficiency of the lasers to higher pump currents, despite the decrease in the energy depth of the quantum wells in the active region.