A5100436419- Phase-change materials and chalcogenides
- Metamaterials and Metasurfaces Applications
- Chalcogenide Semiconductor Thin Films
- Photonic and Optical Devices
- Optical and Acousto-Optic Technologies
- Advanced Antenna and Metasurface Technologies
- Nanowire Synthesis and Applications
- Nonlinear Optical Materials Studies
- Advanced Thermoelectric Materials and Devices
- Semiconductor materials and devices
- Crystallography and molecular interactions
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Optical Polarization and Ellipsometry
- Thermal Radiation and Cooling Technologies
- Transition Metal Oxide Nanomaterials
- solar cell performance optimization
- Optical Coatings and Gratings
- Nonlinear Optical Materials Research
- Advanced Memory and Neural Computing
- Thermography and Photoacoustic Techniques
- Thermal properties of materials
- Liquid Crystal Research Advancements
- Optical Wireless Communication Technologies
- CCD and CMOS Imaging Sensors
Langley Research Center
2012-2025
Korea Advanced Institute of Science and Technology
2004-2025
National Institute of Aerospace
2012-2022
Pusan National University
2022
Dankook University
2007
Tunable narrowband spectral filtering across arbitrary optical wavebands is highly desirable in a plethora of applications, from chemical sensing and hyperspectral imaging to infrared astronomy. Yet, the ability reconfigure properties, with full reversibility, solid-state large-area filter remains elusive. Existing solutions require either moving parts, have slow response times, or provide limited coverage. Here, we demonstrate 1-inch diameter continuously tunable, fully reversible,...
Programmable and reconfigurable optics hold significant potential for transforming a broad spectrum of applications, spanning space explorations to biomedical imaging, gas sensing, optical cloaking. The ability adjust the properties components like filters, lenses, beam steering devices could result in dramatic reductions size, weight, power consumption future optoelectronic devices. Among candidates optics, chalcogenide-based phase change materials (PCMs) offer great promise due their...
Abstract Recent growth in space systems has seen increasing capabilities packed into smaller and lighter Earth observation deep mission spacecraft. Phase-change materials (PCMs) are nonvolatile, reconfigurable, fast-switching, have recently shown a high degree of radiation tolerance, thereby making them an attractive platform for spaceborne photonics applications. They promise robust, lightweight, energy-efficient reconfigurable optical whose functions can be dynamically defined on-demand...
Scientists have predicted that carbon's immediate neighbors on the periodic chart, boron and nitrogen, may also form perfect nanotubes, since advent of carbon nanotubes (CNTs) in 1991. First proposed then synthesized by researchers at UC Berkeley mid 1990's, nitride nanotube (BNNT) has proven very difficult to make until now. Herein we provide an update a catalyst-free method for synthesizing highly crystalline, small diameter BNNTs with high aspect ratio using power laser under pressure...
We demonstrate spectrally-tunable Fabry-Perot bandpass filters operating across the MWIR by utilizing phase-change material GeSbTe (GST) as a tunable cavity medium between two (Ge:Si) distributed Bragg reflectors. The induced refractive index modulation of GST increases cavity’s optical path length, red-shifting passband. Our have spectral-tunability ∼300 nm, transmission efficiencies 60-75% and narrowband FWHMs 50-65 nm (Q-factor ∼70-90). further show multispectral thermal imaging gas...
In this paper, we propose a deep learning approach for forward modeling and inverse design of photonic devices containing embedded active metasurface structures. particular, demonstrate that combining neural network metasurfaces with scattering matrix-based optimization significantly simplifies the computational overhead while facilitating accurate objective-driven design. As an example, apply our to continuously tunable bandpass filter in mid-wave infrared, featuring narrow passband (∼10...
Phase change materials (PCMs) are one of the most promising candidates for reconfigurable optics owing to their two solid-state atomic structures that render distinct optical properties. Recently, there have been growing interests in integrating these into photonic devices achieving In this paper, we focus on examining and thermal properties three essential phase materials: Ge 2 Sb Te 5 , Se 3 S . The latter specifically tailored applications, with minimal absorption losses near-infrared...
Abstract The growing demand for multifunctional nanophotonic devices has led to the exploration, and utilization, of a plethora exotic electro-optical materials. Recently, chalcogenide glass based phase change materials (PCMs) have shown utility as tuning material range devices. Owing their low loss, ultrafast switching speeds wide waveband operation, PCMs are integrated in an increasing number next-generation tunable components, including photonic switches, metasurface optics spectral...
We report on the growth of spinel ZnCo2O4 films using reactive magnetron sputtering and their electrical magnetic properties, with particular emphasis relation Curie–Weiss temperature (TCW) conduction type. The type carrier concentration in these were found to be dependent oxygen partial pressure ratio gas mixture. highest electron hole at 300 K 1.37×1020 2.81×1020 cm−3, respectively. A ferromagnetic coupling (TCW>0) was observable p-type ZnCo2O4, whereas an antiferromagnetic...
Owing to their unique tunable optical properties, chalcogenide phase change materials are increasingly being investigated for optics and photonics applications. However, in situ characterization of transition characteristics is a capability that remains inaccessible many researchers. Herein, multifunctional silicon microheater platform capable measurement structural, kinetic, optical, thermal properties these introduced. The can be fabricated leveraging industry‐standard foundry...
Abstract Reconfigurable or programmable photonic devices are rapidly growing and have become an integral part of many optical systems. The ability to selectively modulate electromagnetic waves through electrical stimuli is crucial in the advancement a variety applications from data communication computing environmental science space explorations. Chalcogenide‐based phase‐change materials (PCMs) one most promising material candidates for reconfigurable photonics due their large contrast...
Electrically tunable optical devices present diverse functionalities for manipulating electromagnetic waves by leveraging elements capable of reversibly switching between different states. This adaptability in adjusting their responses to after fabrication is crucial developing more efficient and compact systems a broad range applications, including sensing, imaging, telecommunications, data storage. Chalcogenide‐based phase‐change materials (PCMs) have shown great promise due stable,...
The photophysical behavior of a series heterometallic arrays made central Sn(IV) porphyrin connected, respectively, to two (SnRu2), four (SnRu4), or six (SnRu6) ruthenium units has been studied in dichloromethane. Two different motifs connect the tin core, axial coordination via ditopic bridging ligands and/or peripheral pyridyl groups ring. A remarkable number electron transfer processes (photoinduced charge separation and recombination processes) have time-resolved using combination...
Abstract The Hinsberg test to recognize the type of amine (1°–3° amines), which has been established for more than 100 years and well documented in textbooks, is not possible without conducting complicated organic reactions. We report first time unique chemosensors that are capable showing selective color changes toward 1°–3° amines as a version test. This simple straightforward qualitative analysis, using synthesized novel compounds herein, can be considered new innovative tool...
The synthesis of graphene nanoribbons on complementary metal–oxide–semiconductor-compatible substrates is a significant challenge hindering their integration into commercial semiconductor electronics. Here, the bottom-up armchair epilayers Ge Si(001) via chemical vapor deposition demonstrated. leverages previous discovery that crystal growth can be driven with an extreme shape anisotropy Ge(001) surfaces to directly form nanoribbons. However, compared nanoribbon Ge(001), Ge/Si(001)...
High-quality strain-relaxed SiGe films with a low twin defect density, high electron mobility, and smooth surface are critical for device fabrication to achieve designed performance. The mobilities of can be few times higher than those silicon due the content carrier germanium (p-type Si: 430 cm 2 /V·s, p-type Ge: 2200 n-type 1300 3000 /V·s at 10 16 per 3 doping density). Therefore, radio frequency devices which made rhombohedral on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Abstract Chalcogenide optical phase change materials (PCMs) have garnered significant interest for their growing applications in programmable photonics, analog computing, active metasurfaces, and beyond. Limited endurance or cycling lifetime is however increasingly becoming a bottleneck toward practical deployment these applications. To address this issue, systematic study elucidating the failure mechanisms of Ge 2 Sb Se 4 Te (GSST) performed, common PCM tailored infrared photonic...
We report the development of a defect-engineered thermoelectric material using Si1−xGex alloys grown on c-plane sapphire substrate via electron beam (E-beam) irradiation. This paper outlines idea growing film at relatively high temperatures to obtain good crystalline properties, then controlling amount twins or dislocations through ex situ electron-beam The current work suggests that structure reconstruction by bond rearrangement E-beam irradiation may be used for tailoring properties.