A5016710908- Semiconductor Lasers and Optical Devices
- Photonic and Optical Devices
- Semiconductor Quantum Structures and Devices
- GaN-based semiconductor devices and materials
- Perovskite Materials and Applications
- Ga2O3 and related materials
- ZnO doping and properties
- Optical Network Technologies
- Photonic Crystals and Applications
- Molecular Junctions and Nanostructures
- Organic Light-Emitting Diodes Research
- Nanowire Synthesis and Applications
- Near-Field Optical Microscopy
- Optical Coatings and Gratings
- Advanced Fiber Optic Sensors
- Advanced Semiconductor Detectors and Materials
- 2D Materials and Applications
- Chalcogenide Semiconductor Thin Films
- Semiconductor materials and devices
- Orbital Angular Momentum in Optics
- Solid-state spectroscopy and crystallography
- Advanced Machining and Optimization Techniques
- Advanced machining processes and optimization
- Conducting polymers and applications
- Quantum Dots Synthesis And Properties
TATI University College
2021-2022
Higher Colleges of Technology
2020
King Abdullah University of Science and Technology
2015-2019
University of Oxford
2019
Telekom Malaysia Berhad (Malaysia)
2004-2013
University of Cyberjaya
2009
Universiti Putra Malaysia
2005-2008
Serdang Hospital
2007
University of Kuala Lumpur
2004
Visible light communication (VLC) is an emerging technology that uses light-emitting diodes (LEDs) or laser for simultaneous illumination and data communication. This envisioned to be a major part of the solution current bottlenecks in wireless However, conventional lighting phosphors are typically integrated with LEDs have limited modulation bandwidth thus cannot provide required realize potential VLC. In this work, we present promising converter VLC by designing solution-processed CsPbBr3...
Hybrid perovskite crystals have emerged as an important class of semiconductors because their remarkable performance in optoelectronics devices. The interface structure and chemistry these are key determinants the device’s performance. Unfortunately, little is known about intrinsic properties surfaces materials extrinsic effects, such complex microstructures, processing conditions, hydration under ambient thought to cause resistive losses high leakage current solar cells. We reveal...
We investigated the mechanisms of radiative recombination in a CH3NH3PbBr3 hybrid perovskite material using low-temperature, power-dependent (77 K), and temperature-dependent photoluminescence (PL) measurements. Two bound-excitonic transitions related to grain size inhomogeneity were identified. Both led PL spectra broadening as result concurrent blue red shifts these excitonic peaks. The red-shifted peak dominated at high excitation true-green wavelength 553 nm for powders that are...
The lack of optical constants information for hybrid perovskite CH3NH3PbBr3 in thin films form can delay the progress efficient LED or laser demonstration. Here, we report on (complex refractive index and dielectric function) using spectroscopic ellipsometry. Due to existence voids, is around 8% less than single crystals counterpart. energy bandgap 2.309 eV as obtained from photoluminescence spectrophotometry spectra, calculated SE analysis. precise measurement will be useful designing devices films.
Group-III nitrides and their alloys feature direct bandgaps covering a broad range of the electromagnetic spectrum, making them promising material system for various applications, such as solid state lighting, chemical/biological sensing, water splitting, medical diagnostics, communications. In recent years, growth strain defect-free group-III nitride vertical nanowires has exploded an area research. These nanowires, grown on unconventional substrates, silicon different metals, demonstrate...
High-quality nitride materials grown on scalable and low-cost metallic substrates are considerably attractive for high-power light-emitters. We demonstrate here, the first time, red (705 nm) InGaN/GaN quantum-disks (Qdisks)-in-nanowire light-emitting diodes (LEDs) self-assembled directly metal-substrates. The LEDs exhibited a low turn-on voltage of ∼2 V without efficiency droop up to injection current 500 mA (1.6 kA/cm(2)) at ∼5 V. This is achieved through direct growth optimization...
To date, solid-state lighting (SSL), visible light communication (VLC), and optical clock generation functionalities in the blue-green color regime have been demonstrated based on discrete devices, including light-emitting diodes, laser transverse-transmission modulators. This work presents first integrated waveguide modulator–laser diode (IWM-LD) at 448 nm, offering advantages of small footprint, high speed, low power consumption. A modulation efficiency 2.68 dB/V, deriving from a large...
The high optical gain and absorption of organic–inorganic hybrid perovskites have attracted attention for photonic device applications. However, owing to the sensitivity organic moieties solvents temperature, processing is challenging, particularly patterning. Here, we report direct patterning using chemically gas-assisted focused-ion beam (GAFIB) etching with XeF2 I2 precursors. We demonstrate enhancement in addition controllability marginal surface damage compared (FIB) without Utilizing...
We report the band alignment parameters of GaN/single-layer (SL) MoS2 heterostructure where GaN thin layer is grown by molecular beam epitaxy on CVD deposited SL-MoS2/c-sapphire. confirm that an SL measuring separation and position room temperature micro-Raman E12g A1g modes, absorbance, micro-photoluminescence bandgap studies. This in good agreement with HRTEM cross-sectional analysis. The determination offset at GaN/SL-MoS2 heterojunction carried out high-resolution X-ray photoelectron...
We study the band discontinuity at GaN/single-layer (SL) WSe2 heterointerface. The GaN thin layer is epitaxially grown by molecular beam epitaxy on chemically vapor deposited SL-WSe2/c-sapphire. confirm that was formed as an SL from structural and optical analyses using atomic force microscopy, scanning transmission electron micro-Raman, absorbance, microphotoluminescence spectra. determination of offset parameters GaN/SL-WSe2 heterojunction obtained high-resolution X-ray photoelectron...
Understanding defect chemistry, particularly ion migration, and its significant effect on the surface's optical electronic properties is one of major challenges impeding development hybrid perovskite-based devices. Here, using both experimental theoretical approaches, we demonstrated that surface layers perovskite crystals may acquire a high concentration positively charged vacancies with complementary negatively halide ions pushed to surface. This charge separation near generates an...
The coherent amplified spontaneous emission and high photoluminescence quantum efficiency of organolead trihalide perovskite have led to research interest in this material for use photonic devices. In paper, the authors present a focused-ion beam patterning strategy methylammonium lead tribromide (MAPbBr3) crystal subwavelength grating nanophotonic applications. essential parameters milling, such as number scan passes, dwell time, ion dose, current, incident angle, gas-assisted etching, were...
Group III-nitride semiconductor materials especially AlGaN are key-emerging candidates for the advancement of ultraviolet (UV) photonic devices. Numerous nanophotonics approaches using nanostructures (e.g., nanowires, nanorods, and quantum dots/disks) nanofabrication substrate patterning, crystals, nanogratings, surface-plasmons) have been demonstrated to address material growth challenges enhance device efficiencies devices operating at UV wavelengths. Here, we review progress...
We experimentally introduce a normalized differential method to enhance the time domain signal-to-noise ratio (SNR) of an optical fiber distributed acoustic sensor (DAS). The reported is calibrated against typical in noisy DAS systems, including those utilizing relatively wide linewidth laser or few-mode fiber. In these two respectively identifies position information various vibration events with 1.7 dB and 0.53 SNR improvement. further demonstrate ability locate positions along that are...
Hybrid organic–inorganic perovskite crystals have recently become one of the most important classes photoactive materials in solar cell and optoelectronic communities. Albeit improvements focused on state-of-the-art technology including various fabrication methods, device architectures, surface passivation, progress is yet to be made understanding actual operational temperature electronic properties performances. Therefore, substantial effect properties, charge separation, recombination...
Recent interest in two-dimensional materials has resulted ultra-thin devices based on the transfer of transition metal dichalcogenides (TMDs) onto other TMDs or III-nitride materials. In this investigation, we realized p-type monolayer (ML) MoS2, and intrinsic GaN/p-type MoS2 heterojunction by GaN overgrowth ML-MoS2/c-sapphire using plasma-assisted molecular beam epitaxy. A systematic nitrogen plasma (N2*) gallium (Ga) irradiation studies are employed to understand individual effect doping...
A nanowire (NW) structure provides an alternative scheme for deep ultraviolet light emitting diodes (DUV-LEDs) that promises high material quality and better extraction efficiency (LEE).In this report, we investigate the influence of tapering angle closely packed AlGaN NWs, which is found to exist naturally in molecular beam epitaxy (MBE) grown NW structures, on LEE DUV-LEDs.It observed that, by having a small angle, vertical greatly enhanced both transverse magnetic (TM) electric (TE)...
We report the use of 3D-printed microscale spiral phase plates to generate orbital angular momentum (OAM) carrying beams. confirm that generated beams have high purity, and we successfully tested them convey data signals with low bit error rates at wavelength 980 nm. This method will open new opportunities for generating OAM many applications in optical communications, including free-space optics, as well underwater, chip-tochip, quantum communications.
We report an optically pumped green perovskite verticalcavity surface-emitter operating in continuous-wave (CW) with a power density threshold of ∼89 kW∕cm 2 .The device has active region CH 3 NH PbBr embedded dielectric microcavity; this feat was achieved combination optimal spectral alignment the optical cavity modes gain, adequate Q-factor microcavity, thermal stability, and improved material quality smooth, passivated, annealed thin layer.Our results signify way towards efficient CW...
We experimentally investigated the performance of a distributed acoustic sensor (DAS) designed using few-mode fiber (FMF), when launching different spatial modes under intentional index perturbation within fiber. Our demonstration showed that quasi-single mode (QSM) operated FMF offers higher signal-to-noise ratio (SNR) for DAS, compared with case other degenerate order modes. Additionally, we behavior single-mode (SMF)- and FMF-based DAS optical pulses varying power levels. The enables...
Group-III-nitride laser diode (LD)-based solid-state lighting device has been demonstrated to be droop-free compared light-emitting diodes (LEDs), and highly energy-efficient that of the traditional incandescent fluorescent white light systems. The YAG:Ce3+ phosphor used in LD-based lighting, however, is associated with rapid degradation issue. An alternate phosphor/LD architecture, which capable sustaining high temperature, power density, while still intensity- bandwidth-tunable for...
The fabrication of orange‐emitting semiconductor laser on interdiffused InGaP/InAlGaP structure is reported. lasers lased at 22°C a wavelength as short 608 nm with threshold current density 3.4 KAcm −2 and maximum output power ∼46 mW. This the shortest electrically pumped emission from structure.
High-speed implant-confined photonic crystal vertical-cavity surface-emitting laser (VCSEL) diodes are fabricated and characterized. The maximum achievable 3-dB bandwidth is a function of both the index confinement provided by etched pattern (which serves to reduce diffraction loss provide for stabilized fundamental mode operation) increased parasitic resistance caused removal doped material. In optimized designs, reduction in net can more than offset parasitics, resulting higher possible an...