Sajid Muhaimin Choudhury

• Doctor of Philosophy
• Professor (Associate) at Bangladesh University of Engineering and Technology

Photonic topological insulators provide unidirectional, robust, wavelength-selective transport of light at an interface while keeping it insulated at the bulk of the material. The non-trivial topology results in an immunity to backscattering, sharp turns, and fabrication defects. This work leverages these unique properties to design a 2-channel opt...

The hybrid metal-dielectric nanostructures (HMDN) are promising candidates to address the ohmic loss by conventional nanostructures in photovoltaic applications by strong confinement and high scattering directivity. In this study, we present a c-Si/TiO$_2$ heterojunction thin film solar cell (TFSC) where a pair of triangular HMDN comprised of Ag an...

This study introduces a dual-band plasmonic absorber designed for simultaneous sensing applications in the near-infrared (NIR) and mid-infrared (MIR) regions. The absorber, composed of silver nanostructures on a metal plate with a dielectric spacer, exhibits a combination of localized and gap surface plasmon resonances, resulting in two distinct ab...

The conventional fiber communication band of 1.55 µm is reaching its limit attributable to the escalation in bandwidth requirements for high-speed and bulk data transmission. Researchers are exploring a 2 µm waveband for its higher capacity and low attenuation as a solution for the next generation communication technologies. Accordingly, here we re...

Researchers have shown considerable interest in two-dimensional silicon carbide recently be-cause of its relatively high exciton binding energy and wide bandgap. This article focuses on analyzing and studying first-principles density functional theory to assess the influence of strain on the phonon, mechanical, optical, and electronic characteristi...

In this article, we report, to the best of our knowledge, for the first time, phase change material (PCM)-based reconfigurable metasurfaces for tailoring different degrees of freedom (DoF) of the quantum emitter (QE) emission, namely polarization and directionality, two key controlling factors in applications such as quantum computing, communicatio...

Photonic topological insulators provide unidirectional, robust, wavelength-selective transport of light at an interface while keeping it insulated at the bulk of the material. The non-trivial topology results in an immunity to backscattering, sharp turns, and fabrication defects. This work leverages these unique properties to design a 2-channel opt...

In this article, we report, for the first time, broadband multifunctional metasurfaces with more than four distinct functionalities. The constituent meta-atoms combine two different phase change materials, $\mathrm{VO_2}$ and $\mathrm{Sb_2S_3}$ in a multi-stage configuration. FDTD simulations demonstrate a broadband reflection amplitude switching b...

In this paper, a novel clock has been implemented in hardware, integrating time, weekday, and Bangla and English dates. Time synchronization is based on the concept of the Internet of Things (IoT), enabling automatic synchronization of time and dates with the standard time via the Internet at periodic intervals. We have used two LED matrices f...

In this article, we propose a broadband reconfigurable multifunctional meta-structure for the first time in the visible range. This device can be reconfigured between an achromatic metalens and a broadband absorber by switching the state of the phase change material (VO2). Our designed VO2 based novel multistage meta-atoms helped us overcome the in...

In this article, we propose a broadband reconfigurable multifunctional meta-structure for the first time in the visible range. This device can be reconfigured between an achromatic metalens and a broadband absorber by switching the state of the phase change material (VO₂). Our designed VO₂ based novel multistage meta-atoms helped us overcome the in...

In this article, we propose a broadband reconfigurable multifunctional meta-structure for the first time in the visible range. This device can be reconfigured between an achromatic metalens and a broadband absorber by switching the state of the phase change material (VO₂). Our designed VO₂ based novel multistage meta-atoms helped us overcome the in...

Biomimicry has been utilized in many branches of science and engineering to develop devices for enhanced and better performances. The application of nanotechnology has made life easier in modern times. It has offered a way to manipulate matter and systems at the atomic level. As a result, miniaturization of numerous devices has been possible. Of la...

In this study, we present an all-optical reflection modulator for 2$\mu$m communication band exploiting a nano-gear-array metasurface and a phase-change-material Ge$_2$Sb$_2$Te$_5$ (GST). The reflectance of the structure can be manipulated by altering the phase of GST by employing optical stimuli. The paper shows details on the optical and opto-the...

Biomimicry has been utilized in many branches of science and engineering to develop devices for enhanced and better performance. The application of nanotechnology has made life easier in modern times. It has offered a way to manipulate matter and systems at the atomic level. As a result, the miniaturization of numerous devices has been possible. Of...

In this study, we present an all-optical reflection modulator for the 2 µm communication band exploiting a nanogear-array metasurface and phase-change-material ${{\rm Ge}_2}{{\rm Sb}_2}{{\rm Te}_5}$ (GST). The reflectance of the structure can be manipulated by altering the phase of GST by employing optical stimuli, and this paper provides details o...

In this paper, we have presented a novel plasmonic Refractive Index (RI) sensing scheme based on a rewritable optical disc structure with customized dimer-like nanopatterns. We have performed the finite-difference time-domain (FDTD) simulation for this work to exhibit the optical resonant response and sensing performance of our proposed sensing pla...

We report a refractive index sensor comprising a unique T-grating on top of periodic nano-cavities. The sensor has two resonant modes sensitive to different regions of the structure with low inter-region interference, hence allowing simultaneous detection of two different analytes or more accurate detection of a single analyte. The sensor also prov...

We report a refractive index sensor comprising of unique T grating on top of periodic nano-cavities. The sensor has two resonant modes sensitive to different regions of the structure with low inter-region interference, hence allows simultaneous detection of two different analytes or more accurate detection of a single analyte. The sensor also provi...

Due to changes in our climate and constant loss of habitat for animals, new pathogens for humans are constantly erupting. SARS-CoV-2 virus, become so infectious and deadly that they put new challenge to the whole technological advancement of healthcare. Within this very decade, several other deadly virus outbreaks were witnessed by humans such as Z...

Our atmosphere is constantly changing and new pathogens are erupting now and then and the existing pathogens are mutating continuously. Some pathogens become so deadly that they put the whole technological advancement of humans under question-such as the case of SARS-CoV-2, however, this is not the only time. SARS-CoV-2 has become a pandemic but wi...

We present a gear-shaped plasmonic nano-structure with structural tunability and high RI sensitivity. New tunable geometric parameters of the gear-tooth give further flexibility for design. By using FDTD method, the reflection spectrum of the structure is theoretically analyzed with analyte RI in the range of 1.0 to 1.44. The best achieved sensitiv...

Surface plasmon resonance (SPR) based sensors are state of the art in bio-sensing. Here we numerically inspect a device that can induce SPR on the opposite side of planar metal films. The evanescent field of SPR can detect wide of refractive index with linear sensitivity. This device modeled on bendable PDMS substrate can launch SPR modes with perp...

Since ancient times, plasmonic structural coloring has inspired humanity; glassmakers achieved vibrant colors by doping glass with metal nanoparticles to craft beautiful objects such as the Roman Lycurgus cup and stained glass. These lovely color filtering effects are a consequence of the resonant coupling of light and free electrons in metal nanop...

Refractive index (RI) sensing helps to identify biomolecules and chemicals in the mid-infrared range for drug discovery, bioengineering, and environmental monitoring. In this paper, we numerically demonstrate an electrically tunable RI sensor with ultrahigh sensitivity using a three-layer graphene nanoribbon array separated by hexagonal boron nitri...

Metasurfaces are thin two-dimensional metamaterial layers that allow or inhibit the propagation of electromagnetic waves in desired directions. For example, metasurfaces have been demonstrated to produce unusual scattering properties of incident plane waves or to guide and modulate surface waves to obtain desired radiation properties. These propert...

Active control over the flow of light is highly desirable because of its applicability to information processing, telecommunication, and spectroscopic imaging. In this paper, employing the tunability of carrier density in a 1-nm titanium nitride (TiN) film, we numerically demonstrate a deep phase modulation (PM) in an electrically tunable gold stri...

Optical metasurfaces are judicously engineered electromagnetic interfaces that can control and manipulate many of light’s quintessential properties, such as amplitude, phase, and polarization. These artificial surfaces are composed of subwavelength arrays of optical antennas that experience resonant light-matter interaction with incoming electromag...

Bound hybrid plasmon-polariton modes supported by waveguides, which are formed by gold coating of ridges etched into a silica substrate, are analyzed using numerical simulations and investigated experimentally using near-field microscopy at telecom wavelengths (1425–1625 nm). Drastic modifications of the fundamental mode profile along with changes...

This study demonstrates visible color hologram using a plasmonic metasurface. The metasurface is fabricated by perforating nanoslits in a 50 nm thick monocrystalline silver film that is ultrasmooth and has ultralow loss compared to conventional polycrystalline silver films commonly used in plasmonics. The designed plasmonic hologram is the thinnest...

A hybrid plasmonic waveguide fabrication technique has been developed and waveguides have been demonstrated. The developed technique can create similar hybrid waveguide structures and metasurfaces with transition metal nitrides and epitaxial silver.

Conventional plasmonic materials, namely, noble metals, hamper the realization of practical plasmonic devices due to their intrinsic limitations, such as lack of capabilities to tune in real-time their optical properties, failure to assimilate with CMOS standards, and severe degradation at increased temperatures. Transparent conducting oxide (TCO)...

We design and fabricate a Pancharatnam-Berry phase manipulating metasurface to experimentally demonstrate a three-color RGB pattern. The color pattern is produced by illuminating a nanostructured silver metasurface hologram with a white light source.

We propose a new scheme to generate polychromatic holograms by manipulating the Pancharatnam-Berry phase. Using anisotropic transmission characteristics and tuning the resonant wavelengths of nanoslits, multicolor holograms can be produced for arbitrary RGB images.

A computationally fast visual approach of autonomous robot localization with high degree of accuracy is demonstrated. Relative position and orientation of an autonomous robot with respect to a fixed reference point is determined by minimal processing of a monocular image employing projective geometry resulting in very low computational requirements...

We demonstrate that a multilayered nanodisk metasurface based on semiconductor materials offers the design flexibility for tuning the plasmonic resonance by controlling the ratio between the metal and dielectric layers.

TCOs enable the realization of practical plasmonic and metamaterial devices at the telecommunication frequency due to their low optical loss. We have fabricated GZO plasmonic waveplates, which convert linearly polarized light into circularly polarized light.

Frequency Selective Surface (FSS) can be used as a surface frequency dependant translucency - thereby reflecting a particular frequency while allowing other frequencies to pass. In this paper, FSS is used as the ground plane of a Hexaflake fractal patch antenna structure. FSS selectively forms cavity along with the hexaflake patch structure, which...

A novel dual-band circularly polarised patch feed antenna is presented. It is theoretically analysed and simulated. It is optimised with a genetic algorithm (GA) which is capable of producing an antenna design that has a low voltage standing wave ratio (VSWR), low cross-polarisation and large bandwidths but small dimensions. A hybrid finite-element...

In this paper, a linear phased array is synthesized to produce a desired far field radiation pattern with a constraint on sidelobe level and beamwidth. The amplitude of the excitation current of each individual array element is optimized to give desired sidelobe level and beamwidth. A modified particle swarm optimization (PSO) algorithm with a no...

In this paper, an approximate closed-form expression of the electric field of a conical horn with linear flare is formulated. Copolarization and cross polarization component of the electric field are calculated from the spherical field components using Ludwig’s third definition of copolarization and cross polarization. The calculated field expressi...

In this paper, a Pickett Potter horn antenna is designed and analyzed for Ka band operation. The dimensions of horn are optimized so that the cross polarization level is minimized for the operating frequency range. The design and optimization is done based on theoretical analysis of dual mode horn antennas and computer simulation. The copolarizatio...

In this paper, sensitivity models for centre frequency and maximum radiated power of a rectangular microstrip antenna at φ = 0 plane using Effective Length Theory have been developed. A wide operating bandwidth for a single-layer coaxially fed microstrip antenna is obtained by cutting a U shaped slot on the metal patch. The sensitivity of perturbat...

In this paper, an aperture matched horn antenna is designed for operation in the microwave X band region. A conical horn is designed first, and the effect of additional aperture matching structure is studied to find the optimum dimension of the structure. The study is performed through computer simulation by Finite Element Method. Finally, the perf...

A “PC to Microcontroller-based client” text message transfer system has been designed and developed. The communication protocol in physical layer has been developed. The entire system has been prototyped and the performance has been tested. The developed system operates well in the angular range of the IrDA protocol. In low power environment, faith...

A model of the illumination function of cassegrain reflector for a corrugated horn feed is presented here. A conical corrugated feed horn designed for a Ku band cassegrain reflector is simulated. The simulation data is compared to the illumination function. Comparison between the developed illumination function and the widely used quadratic on a pe...

In this paper, a simulation based design and analysis of a conical corrugated horn is performed. The design concentrated on reduction of cross-polarization. Optimizing the parameters for operation in a frequency band rather than a single frequency required multiple simulations and noting the effects of parameter variations. The optimized design alo...

A low cost single phase power factor improvement (PFI) device was designed and implemented for small signal low power loads. The designed PFI keeps the power factor of a load within a specified but adjustable range (0.85-0.90) if the load is within its capacity. The design involved designing of a small signal model load, selecting appropriate capac...