Bakhtiyar Orazbayev
@nu.edu.kz
Physics
Nazarbayev University
RESEARCH, TEACHING, or OTHER INTERESTS
Physics and Astronomy, Acoustics and Ultrasonics, Electrical and Electronic Engineering
Scopus Publications
Scopus Publications
Korlan Ziyatkhan, Bakhtiyar Orazbayev, and Constantinos Valagiannopoulos
Springer Science and Business Media LLC
Bakhtiyar Orazbayev, Matthieu Malléjac, Nicolas Bachelard, Stefan Rotter, and Romain Fleury
Springer Science and Business Media LLC
AbstractLight and sound waves can move objects through the transfer of linear or angular momentum, which has led to the development of optical and acoustic tweezers, with applications ranging from biomedical engineering to quantum optics. Although impressive manipulation results have been achieved, the stringent requirement for a highly controlled, low-reverberant and static environment still hinders the applicability of these techniques in many scenarios. Here we overcome this challenge and demonstrate the manipulation of objects in disordered and dynamic media by optimally tailoring the momentum of sound waves iteratively in the far field. The method does not require information about the object’s physical properties or the spatial structure of the surrounding medium but relies only on a real-time scattering matrix measurement and a positional guide-star. Our experiment demonstrates the possibility of optimally moving and rotating objects to extend the reach of wave-based object manipulation to complex and dynamic scattering media. We envision new opportunities for biomedical applications, sensing and manufacturing.
Abay Koshkimbay, Ildar Yusupov, Bakhtiyar Orazbayev, Alexey Slobozhanyuk, and Constantinos Valagiannopoulos
Institute of Electrical and Electronics Engineers (IEEE)
Thin tubes can trap the electromagnetic (EM) energy, emitted wirelessly from a near-field source. The optimal dimensions of these hollow cylinders are determined for an extensive range of complex permittivities characterizing their material and the reported power enhancement is found practically independent of the antenna location. The spatial distribution of the signal reveals the reshaping in the paths of incoming rays and unveils the nature of the developed resonances in the vicinity of the photonic tubes, for both wave polarizations. The concept is experimentally demonstrated at the UHF band with the use of dense dielectric claddings; enhancement up to two orders of magnitude is recorded. The presented results constitute limits in terms of the EM energy accumulation for a simple configuration and, thus, can be utilized in various wireless power transfer (WPT) applications.
Rustam Chibar, Valeriya Kostyukova, Soibkhon Khajikhanov, Daryn Kenzhebek, Altay Zhakatayev, Bakhtiyar Orazbayev, and Zhanat Kappassov
Institute of Electrical and Electronics Engineers (IEEE)
B. Orazbayev, M. Malléjac, N. Bachelard, S. Rotter, and R. Fleury
IEEE
In this paper, we experimentally demonstrate the ability to move an object in disordered and dynamic media by using acoustic waves for transferring linear or angular momentum to the object. In contrast to the remarkable results that have been achieved in optical or acoustical tweezers, our approach overcomes the strict requirements for the environment, such as a tightly controlled environment with minimal reverberation and static conditions. Furthermore, we demonstrate that knowledge of the physical attributes of objects or the composition of the surrounding medium is not needed. Instead, we acquire scattering information and the position of the object to adjust the incident wavefronts iteratively as it moves, and operate only from the far field. Finally, we demonstrate the method’s robustness to substantial alterations in the scattering medium.
Dinmukhammed Mukashev, Nurdaulet Zhuzbay, Ainur Koshkinbayeva, Bakhtiyar Orazbayev, and Zhanat Kappassov
MDPI AG
The sense of touch is fundamental for a one-to-one mapping between the environment and a robot that physically interacts with the environment. Herein, we describe a tactile fingertip design that can robustly detect interaction forces given data collected from a camera. This design is based on the photoelastic effect observed in silicone matter. Under the force applied to the silicone rubber, owing to the stress-induced birefringence, the light propagating within the silicone rubber is subjected to the angular phase shift, where the latter is proportional to the increase in the image brightness in the camera frames. We present the calibration and test results of the photoelastic sensor design on a bench using a robot arm and with a certified industrial force torque sensor. We also discuss the applications of this sensor design and its potential relationship with human mechano-transduction receptors. We achieved a force sensing range of up to 8 N with a force resolution of around 0.5 N. The photoelastic tactile fingertip is suitable for robot grasping and might lead to further progress in robust tactile sensing.
Danissa Sandykbayeva, Zhanat Kappassov, and Bakhtiyar Orazbayev
MDPI AG
Accurate and fast contact detection between a robot manipulator and objects is crucial for safe robot–object and human–robot interactions. Traditional collision detection techniques relied on force–torque sensors and Columb friction cone estimation. However, the strain gauges used in the conventional force sensors require low-noise and high-precision electronics to deliver the signal to the final user. The Signal-to-Noise Ratio (SNR) in these devices is still an issue in light contact detection. On the other hand, the Eccentric Rotating Mass (ERM) motors are very sensitive to subtle touch as their vibrating resonant state loses immediately. The vibration, in this case, plays a core role in triggering the tactile event. This project’s primary goal is to use generated and received vibrations to establish the scope of object properties that can be obtained through low-frequency generation on one end and Fourier analysis of the accelerometer data on the other end. The main idea behind the system is the phenomenon of change in vibration propagation patterns depending on the grip properties. Moreover, the project’s original aim is to gather enough information on vibration feedback on objects of various properties and compare them. These data sets are further analyzed in terms of frequency and applied grip force correlations in order to prepare the ground for pattern extraction and recognition based on the physical properties of an object.
Rayehe Karimi Mahabadi, Taha Goudarzi, Romain Fleury, Bakhtiyar Orazbayev, and Reza Naghdabadi
IOP Publishing
Abstract Tunable metamaterials functionalities change in response to external stimuli. Mechanical deformation is known to be an efficient approach to tune the electromagnetic response of a deformable metamaterial. However, in the case of large mechanical deformations, which are usually required to fully exploit the potential of the tunable metamaterials, the linear elastic mechanical analysis is no longer suitable. Nevertheless, nonlinear mechanical analysis is missing in the studies of mechanically tunable metamaterials. In this paper, we study the importance of considering nonlinearity in mechanical behavior when analyzing the response of a deformable metamaterial and its effects on electromagnetic behavior. We consider a microwave metamaterial formed by copper four-cut split ring resonators on a Polydimethylsiloxane (PDMS) substrate. Applying both displacement and force stimuli, we show that when the deformation is large, more than 10 percent strain, the use of nonlinear analysis considering the geometrical and material nonlinearities is imperative. We further show that the discrepancies between the linear and nonlinear analyses appear in overestimating the stress, underestimating the tunability of the metamaterial responses, and mispredicting the negative permeability regions.
I. Jauregui-Lopez, B. Orazbayev, V. Pacheco-Pena, and M. Beruete
IEEE
In this work, we propose, design, and evaluate three types of: three types of metasurfaces using tripod-shaped unit cells when working as thin-film sensing devices. The three meta-atoms of the proposed metasensors are a simple solid tripod, a hollow tripod, and a hollow tripod structure with arms. The best design showed a mean numerical sensitivity of 1.42 × 10-4 nm for extremely thin samples, meaning an improvement of 381% with respect to the initial designs. These results highlight the importance of using metastructures with complex geometries that enable high-intensity electric field distributions over the whole metasurface.
B. Orazbayev and R. Fleury
IEEE
In this work, we demonstrate theoretically and experimentally the ability to classify and reconstruct subwavelength acoustic images from far field measurements using a machine learning approach, combined with a locally resonant metamaterial lens placed in the near field. In contrast to other near and far field microscopy techniques that also overcomes the diffraction limit but often uses invasive markers or complicated image post-processing, the proposed deep learning approach, once trained, represents a rapid, noninvasive method. Importantly, we show that the relatively large amount of absorption losses present in the resonant metamaterial largely favors the learning and imaging process. With a learning experiment using airborne sound, we recover the fine details of images in the far field, with features at least thirty times smaller than the acoustic wavelength.
Alexia Moreno-Peñarrubia, Jorge Teniente, Sergei Kuznetsov, Bakhtiyar Orazbayev, and Miguel Beruete
AIP Publishing
Applying the Pancharatnam–Berry (PB) principle to half-wave plate (HWP) metasurfaces allows the manipulation of wavefronts along with the conversion of the handedness of circularly polarized incident waves by simply rotating the meta-atoms that compose the metasurface. PB metasurfaces (PBM) working in transmission mode with four or more layers have been demonstrated to reach levels of transmission efficiency near 100% but also have resulted in bulky structures. On the other hand, compact tri-layer ultrathin (λ/8) designs have reached levels near 90% but are more challenging than single- or bi-layer structures from a manufacturing viewpoint. Here, we propose a compact ultrathin (<λ/13) transmissive PBM with only two layers (which significantly simplifies the fabrication process) achieving a transmission efficiency level of around 90%, focusing the wavefront of a circularly polarized incident wave and converting its handedness. The metasurface is composed of identical bi-layered H-shaped unit cells (meta-atoms) whose transmission phases are chosen by introducing different rotation angles to each unit cell according to a lens spatial phase profile. The structure is analytically and numerically studied and experimentally measured, verifying an excellent behavior as an HWP PB metalens at 87 GHz.
Bakhtiyar Orazbayev and Romain Fleury
American Physical Society (APS)
Seeing and recognizing an object whose size is much smaller than the illumination wavelength is a challenging task for an observer placed in the far field, due to the diffraction limit. Recent advances in near and far field microscopy have offered several ways to overcome this limitation; however, they often use invasive markers and require intricate equipment with complicated image post-processing. On the other hand, a simple marker-free solution for high-resolution imaging may be found by exploiting resonant metamaterial lenses that can convert the subwavelength image information contained in the near-field of the object to propagating field components that can reach the far field. Unfortunately, resonant metalenses are inevitably sensitive to absorption losses, which has so far largely hindered their practical applications. Here, we solve this vexing problem and show that this limitation can be turned into an advantage when metalenses are combined with deep learning techniques. We demonstrate that combining deep learning with lossy metalenses allows recognizing and imaging largely subwavelength features directly from the far field. Our acoustic learning experiment shows that, despite being thirty times smaller than the wavelength of sound, the fine details of images can be successfully reconstructed and recognized in the far field, which is crucially enabled by the presence of absorption. We envision applications in acoustic image analysis, feature detection, object classification, or as a novel noninvasive acoustic sensing tool in biomedical applications.
Irati Jáuregui-López, Bakhtiyar Orazbayev, Victor Pacheco-Peña, and Miguel Beruete
MDPI AG
The high electric field intensity achieved on the surface of sensors based on metasurfaces (metasensors) makes them an excellent alternative for sensing applications where the volume of the sample to be identified is tiny (for instance, thin-film sensing devices). Various shapes and geometries have been proposed recently for the design of these metasensors unit-cells (meta-atoms) such as split ring resonators or hole arrays, among others. In this paper, we propose, design, and evaluate two types of tripod metasurfaces with different complexity in their geometry. An in-depth comparison of their performance is presented when using them as thin-film sensor devices. The meta-atoms of the proposed metasensors consist of a simple tripod and a hollow tripod structure. From numerical calculations, it is shown that the best geometry to perform thin-film sensing is the compact hollow tripod (due to the highest electric field on its surface) with a mean sensitivity of 3.72 × 10−5 nm−1. Different modifications are made to this structure to improve this value, such as introducing arms in the design and rotating the metallic pattern 30 degrees. The best sensitivity achieved for extremely thin film analytes (5–25 nm thick) has an average value of 1.42 × 10−4 nm, which translates into an extremely high improvement of 381% with respect to the initial hollow tripod structure. Finally, a comparison with other designs found in the literature shows that our design is at the top of the ranking, improving the overall performance by more than one order of magnitude. These results highlight the importance of using metastructures with more complex geometries so that a higher electric field intensity distribution and, therefore, designs with better performance can be obtained.
Bakhtiyar Orazbayev, Nadege Kaina, and Romain Fleury
IEEE
Guiding electromagnetic energy at a subwavelength scale is one of the most highly demanded functionalities in a variety of applications, including compact, lightweight satellite communications, signal and data processing, and power systems. The existing schemes for subwavelength waveguiding, including topological designs, are usually based on the use of locally resonant metamaterials and generally sensitive to the lattice imperfections and disorder-induced backscattering. We quantitatively assess here the robustness of subwavelength edge modes in different waveguide designs, including designs based on C6 symmetry or valley-Hall (VH) topological insulators (TI) and non-topological designs based on chirality or a frequency defect line. The statistical results demonstrate that all waveguiding schemes provide a different level of robustness of the edge modes for different types of disorder and superior robustness of VH and chiral metamaterial waveguides to all three types of disorder.
Bakhtiyar Orazbayev, Nadege Kaina, and Romain Fleury
IEEE
Rapid progress in all types of communication systems imposes each time more strict requirements on the communication devices, requiring having the overall device's size as small as possible, but also increasing the demands on the robustness of the transmission channels to the disorders with an aim of achieving most efficient signal transmission. The existing schemes for transferring signals, based on the conventional materials, are tied to the operation wavelength of the propagating signal and therefore fundamentally limited by it. Moreover, in such schemes the absence of any sort of protection renders them vulnerable to possible defects in the channel, forcing the use of additional elements (for instance filters, amplifiers, etc.) and increasing the overall size and cost of the devices. However, recent developments in the field of artificial media, known as metamaterials [1], showed a great potential for achieving more control over the wave propagation and providing viable solutions for an efficient signal transmission. Unfortunately, since these artificial media consist of resonant inclusions - meta-atoms, they are inherently susceptible to geometrical imperfections and disorder-induced backscattering, which significantly reduces their performance and limits their real applications.
Bakhtiyar Orazbayev, Nadege Kaina, and Romain Fleury
IEEE
In this work, we design and experimentally demonstrate in the microwave range a robust metamaterial waveguide, which is formed at the boundary between two locally resonant chiral metamaterials with opposite chirality. We show that the interface states at such boundary are inherently robust to disorder in both the position and resonance frequency of subwavelength resonators. Moreover, we quantitatively demonstrate the superiority of the proposed subwavelength waveguiding over previously proposed designs, including frequency-defect lines, symmetry-based topological edge modes, and Valley-Hall interface states.
Bakhtiyar Orazbayev and Romain Fleury
Walter de Gruyter GmbH
Abstract Recent advances in designing time-reversal-invariant photonic topological insulators have been extended down to the deep subwavelength scale, by employing synthetic photonic matter made of dense periodic arrangements of subwavelength resonant scatterers. Interestingly, such topological metamaterial crystals support edge states that are localized in subwavelength volumes at topological boundaries, providing a unique way to design subwavelength waveguides based on engineering the topology of bulk metamaterial insulators. While the existence of these edge modes is guaranteed by topology, their robustness to backscattering is often incomplete, as time-reversed photonic modes can always be coupled to each other by virtue of reciprocity. Unlike electronic spins which are protected by Kramers theorem, photonic spins are mostly protected by weaker symmetries like crystal symmetries or valley conservation. In this paper, we quantitatively studied the robustness of subwavelength edge modes originating from two frequently used topological designs, namely metamaterial spin-Hall (SP) effect based on C6 symmetry, and metamaterial valley-Hall (VH) insulators based on valley preservation. For the first time, robustness is evaluated for position and frequency disorder and for all possible interface types, by performing ensemble average of the edge mode transmission through many random realizations of disorder. In contrast to our results in the previous study on the chiral metamaterial waveguide, the statistical study presented here demonstrates the importance of the specific interface on the robustness of these edge modes and the superior robustness of the VH edge stated in both position and frequency disorder, provided one works with a zigzag interface.
B. Orazbayev, N. Kaina, and R. Fleury
American Physical Society (APS)
Routing electromagnetic energy at a scale smaller than the wavelength is a highly sought functionality in a variety of applications, including compact lightweight satellite communications, slow-waves sensors, all-optical information processing, and energy harvesting. Unfortunately, strong field confinement at this scale requires the use of coupled subwavelength resonators, implying a large sensitivity to geometrical imperfections and disorder-induced backscattering. We propose a very unconventional solution to this problem by exploiting the interface modes occurring at the boundary between two chiral metamaterials composed of resonant metamolecules with opposite chirality. Our numerical and experimental results demonstrate the inherent robustness of these interface states to disorder in both the position and resonance frequency of the metamaterial’s meta-atoms. By computing transmission averages over many realizations of disorder, we quantitatively demonstrate the superiority of this form of subwavelength routing over previously proposed designs, including frequency-defect lines, symmetry-based topological edge modes, and Valley-Hall interface states.
B. Orazbayev, P. Rodríguez-Ulibarri, and M. Beruete
Institution of Engineering and Technology
B. Orazbayev, M. Beruete, A. Martinez, and C. Garcia-Meca
IEEE
In this work we design an unidirectional invisibility cloak for a diffusive-light medium based on transformation optics, which provides a broadband, passive and polarization-independent performance and can conceal macroscopic objects. Unlike the other cloaking designs based on scattering cancellation or transformation optics, our design can work under transient illumination, which is crucial in many applications, like time-of-flight imaging or high-speed communication systems. We demonstrate that this technique can also be applied to achieve a multidirectional performance with a polygonal cloak. Moreover, we propose and analyze a simpler design of unidirectional cloak based on a layered stack of two isotropic materials. The performance of the designed cloaks is numerically analyzed in transient regime and the successful concealment of the object is confirmed.
Bakhtiyar Orazbayev, Pablo Rodríguez-Ulibarri, and Miguel Beruete
Optica Publishing Group
Backscattering reduction is usually achieved by using either absorbers or diffractions gratings at the expense of a narrow bandwidth. In this paper, we propose a different strategy based on a metallic compound reflection grating (CRG). We demonstrate that this structure allows a strong and broadband (fractional bandwidth, FBW ≈57%) backscattering reduction in the terahertz (THz) range by efficiently transferring the incident energy to the diffracted modes. The design is analyzed in terms of equivalent circuit and numerical simulations and the results are corroborated by a manufactured prototype operating at 0.35 THz.
Alicia E. Torres-Garcia, Bakhtiyar Orazbayev, Inigo Ederra, and Ramon Gonzalo
IEEE
A Fresnel Zone Plate Lens designed for the Mid-IR is modified for acting as a THz Antenna. This proposal is the base for a dual band detector consisting of a Silicon (Si) substrate with a quasi-spiral antenna detector working at THz frequencies which acts also as a modified Fresnel Zone Plate Lens for an IR detector. The focal properties of the proposed lens have been studied numerically, and its behavior as a submillimeter wave receiver has been demonstrated by a 3D full-wave simulator.
Bakhtiyar Orazbayev, Miguel Beruete, and Irina Khromova
IEEE
In this work we demonstrate three different designs of tunable mid-infrared (MIR) beam steering devices based on multilayer graphene-dielectric metamaterials. In all designs the tunable beam steering is achieved by controlling the effective refractive index of the graphene metamaterial, which is done by changing the chemical potential of each graphene layer. The proposed beam steerer concepts allow a wide range of output angles (up to approximately 70 deg) and low reflection losses. The graphene-based tunable beam steering can be used in tunable transmitter/receiver modules for infrared imaging and sensing.
Bakhtiyar Orazbayev, Nasim Mohammadi Estakhri, Andrea Alù, and Miguel Beruete
Wiley
This is the peer reviewed version of the following article: B. Orazbayev, N. Mohammadi Estakhri, A. Alu, M. Beruete, Advanced Optical Materials 2017, 5, 1600606, which has been published in final form at http://dx.doi.org/10.1002/adom.201600606. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.