Nikolay Petrov

ITMO University | SPbNRU ITMO · Department of Photonics and Optical Information Technology

Terahertz pulse time-domain holography (THz PTDH) is the powerful technique for high-resolution amplitude and phase THz imaging that allows mapping spectroscopic information across the imaged object. In this paper, we consider most sought after applications of phase imaging provided by this technique and experimentally demonstrate the ability of th...

Recent works demonstrated that digital time-resolved holography is the prospective approach to study nonlinear light–matter interaction processes. In this Letter, we present a straightforward inline holographic approach for studying degenerate phase modulation induced by an inclined collimated pump beam in the isotropic sample. The method is based...

A comprehensive characterization of the diffraction properties of terahertz (THz) pulsed broadband vortex beams consisting of several electromagnetic field oscillations requires state-of-the-art techniques for studying the evolution of a wavefront as it propagates. For this purpose, we have applied the capabilities offered by THz pulse time domain...

Terahertz phase retrieval is a promising technique able to assess the complex diffracted wave properties through an iterative processing algorithm. In this Letter, we demonstrate the implementation of this technique in reflection geometry with a continuous wave acquisition system working at 0.287 THz. To ensure a high signal-to-noise ratio in the m...

In this paper, we review the existing approaches for vortex and vector beam shaping and generation in the terahertz frequency range. The particular focus of this review is on the possibility of homogeneous topological charge formation in the ultra-wide spectral interval inherent to ultrashort terahertz pulses. We review the available materials and...

In this paper, we demonstrate the capabilities of the terahertz pulse time-domain holography in visualisation, simulation, and assessment of broadband THz vortex beam formation dynamics upon its shaping by elements of beam converter, and further propagation and manipulation. By adding Jones matrix formalism to describe broadband optical elements, w...

The aim of this article is to demonstrate the possibility of using photogrammetry as a method for documenting and digitizing data reconstructed from a display hologram. We discuss the importance of the task of digitizing information from holograms and the search for its solution, which will allow display holography to gain new distribution. Texture...

The paper presents the results of a comprehensive study on the optimization of independent amplitude and phase wavefront manipulation which is implemented using a binary digital micromirror device. The study aims to investigate the spatial resolution and quantization achievable using this approach and its optimization based on the parameters of the...

In this paper, we detail a phase-shift implementation in a rotated plane-parallel plate (PPP). Considering the phase-shifting digital holography application, we provide a more precise phase-shift estimation based on PPP thickness, rotation, and mutual inclination of reference and object wavefronts. We show that phase retardation uncertainty impleme...

We report on the application of time-resolved inline digital holography in the study of the nonlinear optical properties of quantum dots deposited onto sample glass. The Fresnel diffraction patterns of the probe pulse due to noncollinear degenerate phase modulation induced by a femtosecond pump pulse were extracted from the set of inline digital ho...

“My main goal was to point out new phenomena and spread the ideas, which will become the starting points for new research” (Nikola Tesla) [...]

Terahertz phase retrieval from a set of axially separated diffractive intensity distributions is a promising single-beam computational imaging technique that ensures the obtention of high spatial resolutions and phase wavefronts, but remains restricted by time-consuming data acquisition processes. In this work, we have adopted an approach, relying...

Recently, intelligent data analysis and neural networks are increasingly used to detect the wavefront by interferograms and digital holograms. In this case, there is significant freedom to choose the structure of the reference beam. In this paper, a comparative study of the effectiveness of the neural network was performed to solve the problem of t...

We report on the application of time-resolved inline digital holography to study the nonlinear optical properties of quantum dots deposited onto the sample glass. Fresnel diffraction patterns of the probe pulse due to noncollinear degenerate phase modulation induced by the femtosecond pump pulse were extracted from the set of inline digital hologra...

We present a holographic detection module to measure the spatially resolved distribution of pulsed terahertz field in a single scan by a motorized translation stage, responsible for the time delay. All mounts of the optical elements of the module are easily reproduced by 3D printing and attached to the optical cage system. The latter greatly simpli...

In this contribution, we discuss the features of design and polarimetric inspection of terahertz achromatic waveplates. The design of the crystalline quartz half-wave plate was performed taking into account the ellipticity and the introduced phase difference between the orthogonal components of the output radiation polarization vector. The designed...

In this paper, we present the result of our study on the development of the digital holographic microscope with a geometric phase lens and the parallel phase-shifting polarization camera. In numerical simulation and the experiment, it was shown that in this configuration, the geometric phase lens leads to a shear interference pattern formation, thu...

Speckle patterns can be very promising for many applications due to their unique properties. This paper presents the possibility of numerically and experimentally formation of speckle patterns using broadband THz radiation. Strong dependence of the statistical parameters of speckles, such as size and sharpness on the parameters of the diffuser are...

Speckle patterns can be very promising for some applications due to their unique properties. This paper presents the possibility of numerically and experimentally formation of speckle patterns using broadband THz radiation. Strong dependence of the statistical parameters of speckles, such as size and sharpness on the parameters of the diffuser are...

We propose a new ptychographic algorithm where the object scanning is performed by the complex-valued probe function, formed in the setup of independent amplitude-phase modulation. The results of numerical experiments demonstrate the effectiveness of the proposed approach.

The paper deals with the edge diffraction of the single charged Laguerre-Gaussian beam outside the waist. Based on the Kirchhoff-Fresnel integral, the behavior of the optical vortex (OV) migration during sequential beam blocking by the straight edge of the screen is performed analytically. Universal combination of the diffracting-beam parameters de...

Digital inline pump-probe holography can be applied to estimate parameters of samples' optical nonlinear properties. Here we propose a mathematical model to describe noncollinear degenerate phase modulation in samples with inhomogeneities of nonlinear refractive index over all three dimensions, namely, two-layered samples and samples with local imp...

An approach to determining the fraction of local inhomogeneities nonlinear refractive index n2 in a transparent medium is considered. Data recording was performed using inline digital holography with femtosecond time resolution, where a set of probe beam inline digital holograms in the Fresnel diffraction zone to be recorded at various time delays...

Time-resolved inline digital holography was validated during study of nonlinear optical properties of graphene microparticles on the sample glass. A set of probe pulse inline digital holograms were recorded and compared with numerically simulated data.

We investigate an optical scheme and possibilities of digital holographic microscope with a geometrical phase lens. The phase imaging capability for micro-objects is verified.

This work demonstrates the encoding principle for wave trains consisting of interfering uniformly charged Laguerre-Gaussian terahertz beams carrying unitary and zero topological charges. Optimization of the receiving aperture and threshold for a binary encoding outcome is presented.

We proposed a simple and cost-effective method to manipulate the temporal and spectral properties of pulsed terahertz waves. A deep modulation of a pulse spectrum was both numerically and experimentally verified using Fresnel apertures with a radius ranging from several to several tens of the central wavelength of the broadband terahertz radiation....

The paper deals with the edge diffraction of the single charged Laguerre-Gaussian beam outside the waist. Based on the Kirchhoff-Fresnel integral, the behavior of the optical vortex (OV) migration during sequential beam blocking by the straight edge of the screen is performed analytically. Universal combination of the diffracting-beam parameters de...

This work describes the promising approach for the diagnostic of diseases, such as diabetes, by using the THz spectroscopy and THz holography method. In this paper, dry pellets consisting of human blood plasma (normal and diabetic) were designed; these objects were analyzed in various THz Russian laboratories, PCA-analysis of THz spectra was applie...

This paper presents the results of a comprehensive study on the optimization of the optical system for independent amplitude and phase wavefront manipulation, which is based on a digital micromirror device implementation. The parameters of generated binary fringe patterns to reach the optimal quality of target complex-valued wavefront have been fou...

Time-resolved inline digital holography is a promising technique for the measurement of optical nonlinear properties of materials. Here we adapt it for the study samples with inhomogeneities in the spatial distribution of the nonlinear refractive index.

In this contribution, we investigate the features of the two-beam interference of a set of wave trains, in which one of the beams contains an orbital angular momentum caused by the presence of inline topologically charged vortices in each spectral component. The infrared pump beam that generates terahertz radiation is first doubled in Mach-Zehnder...

Differences in correlation measurements of the parameters of pulsed hyperspectral optical fields using symmetric and asymmetric interferometers are considered. It is shown analytically that the resulting cross-correlation function is sensitive to phase perturbations in the original wave field. The considered setup, which contains a telescopic refle...

A new method for diagnosis of diabetes mellitus is proposed, which uses for measurement a lyophilized blood plasma sample prepared in the form of a pellet. The paper develops a methodology for fast spectroscopic measurements of such pellets with terahertz pulse time-domain holography. For that reason, blood plasma pellets were experimentally measur...

A novel algorithm for reconstruction of hyperspectral 3D complex domain images (phase/amplitude) from noisy complex domain observations has been developed and studied. This algorithm starts from the SVD (singular value decomposition) analysis of the observed complex-valued data and looks for the optimal low dimension eigenspace. These eigenspace im...

Complex wavefront manipulation is a promising technique for many applications of optics and photonics. In this report we will present our results on development of DMD wavefront correction experimental setup and discussion of its performance for various parameters of binary fringe pattern and 1st diffraction order filtration aperture. It was shown...

In this paper, we present the results of a holographic assessment of the propagational dynamics of broadband pulsed terahertz vortex beams in the scope of their possible applications for near- and medium- field data transfer.

Phase Retrieval at the frequency 0.287 THz is demonstrated through the simulations and the experiments. Single Beam Multiple Intensity Reconstruction algorithm was applied to obtain phase and amplitude images from the set of diffraction patterns.

The report discusses hyperspectral interferometric measurement systems for the tasks of wavefront sensing and amplitude-phase objects reconstruction. The influence of spatial and spectral phase in the interferometer arms are analyzed in numerical simulation.

We investigated the peculiarities of the terahertz pulse time-domain holography principle in the case of raster scanning with the balance detection system. The noise in this system represents a Skellam distribution model, which differentiates it from systems based on a photoconductive antenna. We analyzed this Skellam model and provided both numeri...

Here, we present a comprehensive study of the reconstruction quality in terahertz (THz) pulse time-domain holography. We look into single wavelength reconstructions, as well as broadband recovery enabled by the ultrabroadband nature of radiation and coherent detection enabled by electro-optic or photoconductive sensing. We demonstrate the transvers...

When calculated in the spectral domain, the propagation of an ultrashort optical pulse may suffer from inaccuracy due to the finite thickness of the object it diffracts on. Unlike monochromatic radiation, ultrashort pulse interaction with an object in the time domain depends on the pulse longitudinal coordinate. Here, we propose an algorithm to stu...

In this paper, we consider a Huygens filter for a specified frequency lying within a broad spectrum of a pulsed THz radiation which represents simplest two-zone plate. The condition of the infinite plane wave and the Gaussian beam are separately used as the initial source has been discussed. A property method of terahertz spectral filter has been e...