Physical Sciences and Mathematics Commons^™

Theoretical Investigation On Optical Properties Of 2d Materials And Mechanical Properties Of Polymer Composites At Molecular Level, Geeta Sachdeva

Dissertations, Master's Theses and Master's Reports

The field of two-dimensional (2D) layered materials provides a new platform for studying diverse physical phenomena that are scientifically interesting and relevant for technological applications. Theoretical predictions from atomically resolved computational simulations of 2D materials play a pivotal role in designing and advancing these developments. The focus of this thesis is 2D materials especially graphene and BN studied using density functional theory (DFT) and molecular dynamics (MD) simulations. In the first half of the thesis, the electronic structure and optical properties are discussed for graphene, antimonene, and borophene. It is found that the absorbance in (atomically flat) multilayer antimonene (group …

Computational Study Of Quorum Quenching Of N-Acyl Homoserine Lactones By Ion Pairing To Cations, Ashen Anuradha Suduweli Kondage

Dissertations and Theses

Biofilms are the default state of microbial life and their formation on surfaces influences many processes. The coordinated behavior of microorganisms including their growth into biofilms occurs through a process termed quorum sensing during which they excrete specific signaling molecules called autoinducers. Recently it has been observed that Ag+ and Cu2+ ions interact with N-hexanoyl-L-homoserine autoinducers thereby inhibiting quorum sensing. Such inhibitors are called quorum quenchers. In this study, we have used density functional theory (DFT) calculations to study the ion pairing between select cations and short chained N-acyl-homoserine lactone (AHL) type autoinducers that are used by gram negative bacteria. …

Applications Of Remote Sensing And Geographic Information System On Salinity Assessment: A Case Study On Bang Pakong River, Thailand, Min Thura Mon

Chulalongkorn University Theses and Dissertations (Chula ETD)

The Bang Pakong River (BPK) has an annual salinity issue. The river is an important source of freshwater supply in the Eastern Economic Corridor (EEC) of Thailand, which has major agricultural and industrial activities. This research aims to understand and assess the past and future salinity distribution in the BPK River by using remote sensing and time series forecasting through water quality and Landsat image time series data. Regarding to remote sensing, this research employs four machine learning algorithms—multilinear regression, decision trees, random forest, and artificial neural networks—by applying reflectance bands of satellite images and measured salinity values. Random forest …

Persistence Of Height Fluctuation In Molecular-Beam Epitaxy Model, Pipitton Sanseeha

Chulalongkorn University Theses and Dissertations (Chula ETD)

Persistence probability is an interesting quantity in stochastic process which is the dynamics of surface growth in this study. Persistence probability of height f luctuation is the probability that the height fluctuation does not return to its initial value throughout a time interval. In this work, we use a numerical simulation approach to investigate the persistence probability in Molecular-Beam Epitaxy (MBE) model which is associated with Molecular-Beam Epitaxy technique. First half, we study the effects of temperature and deposition rate on the growth exponent () and persistence exponent (). For the temperature corresponds to 1 diffusion length, we get 017 …

Random Walks On Quasi-1d Infinite Structures, Srawut Sasom

Chulalongkorn University Theses and Dissertations (Chula ETD)

In the present thesis a random walk on quasi-1d lattices as a model for transport processes on quasi-1d materials is analytically investigated. The scope of the present work is to shed light on the asymptotic behavior of basic statistical properties of the random walk on such structures including the first and the second moments of the walker location along the structure axis, the probability of return to the starting site, the probability of ever reach a given site, the conditional mean first-passage time to a given site and the expected number of distinct sites visited. The first part of the …

การผลิตวานิลลินจากเคอร์คูมินอยด์ในขมิ้นชันโดยโอโซโนไลซิส, ภัทรวดี รุ่งศรีทอง

Chulalongkorn University Theses and Dissertations (Chula ETD)

ในปัจจุบันการสังเคราะห์วานิลลินใช้วัตถุดิบตั้งต้นจากอุตสาหกรรมปิโตรเลียม ซึ่งวานิลลินสังเคราะห์นี้ ใช้สำหรับเป็นสารแต่งกลิ่นวานิลลากันอย่างแพร่หลายในอุตสาหกรรมอาหาร อย่างไรก็ตาม การใช้วัตถุดิบตั้งต้นที่สามารถเกิดขึ้นใหม่ได้ตามธรรมชาตินั้น เป็นแนวทางที่มีความยั่งยืนมากกว่า ตามหลักการไบโอรีไฟเนอรี ในงานวิจัยนี้ ผู้วิจัยสนใจศึกษาการผลิตวานิลลินด้วยปฏิกิริยาโอโซโนไลซิส โดยใช้เคอร์คูมินอยด์ที่อยู่ในขมิ้นชันเป็นวัตถุดิบตั้งต้น ขมิ้นชันเป็นพืชสมุนไพรที่ปลูกมากในประเทศไทยและประเทศในแถบเอเชียตะวันออกเฉียงใต้ ซึ่งเคอร์คูมินอยด์นั้นจะประกอบไปด้วย เคอร์คูมิน (curcumin), ดีเมทอกซีเคอร์คูมิน (demethoxycurcumin), และบิสดีเมทอกซีเคอร์คูมิน (bisdemethoxycurcumin) ผู้วิจัยเริ่มจากการสกัดเคอร์คูมินอยด์จากขมิ้นชันผงน้ำหนักประมาณ 45 กรัม ด้วยเทคนิคซอกเลท (Soxhlet extraction) โดยใช้เฮกเซนในการกำจัดน้ำมันหอมระเหยในขมิ้นชัน จากนั้นใช้เมทานอลสำหรับสกัดเคอร์คูมินอยด์ และได้ของผสมเคอร์คูมินอยด์ปริมาณ 9.2% (โดยน้ำหนัก) จากการวิเคราะห์เคอร์คูมินอยด์ที่สกัดได้ด้วยเทคนิคโครมาโทกราฟีของเหลวสมรรถนะสูง (high-perfomance liquid chromatography) พบว่าประกอบไปด้วย เคอร์คูมิน ดีเมทอกซีเคอร์คูมิน และบิสดีเมทอกซีเคอร์คูมิน ในปริมาณ 46%, 22%, และ 32% ตามลำดับ นำของผสมเคอร์คูมินอยด์ดังกล่าวมาทำปฏิกิริยาโอโซโนไลซิสในตัวทำละลายเมทานอลที่อุณหภูมิ 0 องศาเซลเซียสและรีดิวซ์ด้วยไดเมทิลซัลไฟด์ (dimethyl sulfide) ได้ผลิตภัณฑ์เป็นของผสมระหว่างวานิลลินและ 4-ไฮดรอกซีเบนซาลดีไฮด์ (4-hydroxybenzaldehyde) ทำบริสุทธิ์ของผสมที่ได้ด้วยเทคนิคคอลัมน์โครมาโทกราฟี โดยใช้ซิลิกาเจลเป็นวัฏภาคนิ่งและใช้ตัวทำละลายผสมไดคลอโรเมเทน/เมทานอล/กรดแอซีติก (98.5:1.0:0.5 โดยปริมาตร) เป็นวัฏภาคเคลื่อนที่ สามารถแยกสารบริสุทธิ์วานิลลิน 63% และ 4-ไฮดรอกซีเบนซาลดีไฮด์ 97% ผู้วิจัยยังได้ศึกษาการตกผลึกเพื่อเป็นทางเลือกสำหรับการทำบริสุทธิ์ต้นทุนต่ำสำหรับของผสมหลังผ่านปฏิกิริยาโอโซโนไลซิส พบว่าสามารถตกผลึก 4-ไฮดรอกซีเบนซาลดีไฮด์ให้บริสุทธิ์ในปริมาณ 62% ด้วยตัวทำละลายผสมคลอโรฟอร์ม/เฮกเซน (1:1 โดยปริมาตร) อย่างไรก็ตาม ยังมีวานิลลินและ 4-ไฮดรอกซีเบนซาลดีไฮด์ เหลืออยู่ในสารละลายหลังตกผลึก (mother liquor) ในปริมาณ 58% และ 32% ตามลำดับ โดยสรุปผู้วิจัยประสบความสำเร็จในการผลิตวานิลลินและ 4-ไฮดรอกซีเบนซาลดีไฮด์จากขมิ้นชันซึ่งเป็นวัตถุดิบตั้งต้นที่สามารถเกิดขึ้นใหม่ได้ ผ่านปฏิกิริยาโอโซโนไลซิส นับเป็นแนวทางเพิ่มมูลค่าพืชสมุนไพรราคาถูกให้เป็นสารเคมีที่มีมูลค่าสูงขึ้นตามหลักการไบโอรีไฟเนอรี

Addressing Rice Waste In University Cafeterias Using Material Flow Analysis And System Dynamics Modeling, Abigail Marie T. Favis, Charlotte Kendra Z. Gotangco-Gonzales, Ana Erika Lareza

Environmental Science Faculty Publications

Food waste has emerged as one of the focus areas in sustainability research. At the Ateneo de Manila University, previous studies have found that food waste is composed mainly of rice. This study, therefore, analyzed cafeteria rice systems in the university through a material flow analysis (MFA) to identify key factors for formulating effective rice waste reduction techniques and then applied the results toward developing system dynamics (SD) models as tools for decision-making. The MFA found that the total mass of produced known rice waste was 49.48 kg/d. The largest sources of rice wastes were the upstream processes of the …

How Can Microgrids Help The Philippines’ Energy Transition? Adapting The Institutional Analysis And Development (Iad) Framework For Microgrid Development, John Charles A. Altomonte, Hannah Sofia Guinto

Environmental Science Faculty Publications

The Philippine energy sector remains plagued with issues of energy security, high electricity costs, and vulnerable grid infrastructure. This paper argues for the increased uptake of microgrids as a solution for these issues, using the Institutional Analysis and Development (IAD) Framework as a guide for microgrid policy. We begin this paper with an analysis of existing energy policies in the Philippines, highlighting a lacking integrated approach for energy security. The main discussion explores the IAD framework for microgrid development in the Philippines, identifying key barriers and dynamics among institutions and actors in the local energy sector. We then conclude with …

Determinants Of Sustainability: A Case Of Piloting Isard Models In Oriental Mindoro And Leyte, Philippines, Pedcris M. Orencio, Anna Gale Vallez, Ruth Jazrel M. Bandong

Environmental Science Faculty Publications

SEARCA, in its 10th five-year plan (10th FYP), implemented the program, Inclusive and Sustainable Agricultural and Rural Development (ISARD). A pilot project was undertaken in a specific rural community following a well-defined scheme for an agroecosystem and through the integration of four inter-related components, technical assistance, capacity building, knowledge management, and linkage and networking. After the completion in 2020, evidences of well-developed agricultural system capable of contributing to the goals of food security and poverty alleviation emerged. In its 11th FYP, SEARCA endeavors to scale out the ARD model project in the Southeast Asian region. But, how will this benefit …

Phosphorus Use And Management Based On Fertilizer Placement, Rate Of Application, And Soil Biota In No-Till Situations, Brennan Alexander Bingham Lewis

Electronic Theses and Dissertations

Phosphorus (P) pollution has become a concern among multiple scientific organizations as it leads to eutrophication, an algal bloom that depletes lacustrine and marine ecosystems of native species. Multiple strategies can be implemented to reduce phosphorus loss from agriculture fields, which is often implicated as a cause of eutrophication. Soil phosphorus chemistry results in phosphate fertilizers absorbing to clay minerals over time. Soil phosphorus is lost from agricultural fields primarily through wind and water erosion. No-till practices prevent soil erosion, which reduces the phosphorus from loading into waterways. Fertilizer placement affects phosphorus loss. Surface application of phosphorus fertilizers increases the …

Targeted Browsing With Goats For Eastern Redcedar (Juniperus Virginiana L.) Control, Alanna M. Hartsfield

Electronic Theses and Dissertations

As eastern redcedar (ERC) (Juniperus virginiana L.) grassland encroachment progresses, all potential control methods should be explored in the interest of Great Plains grassland health and longevity. Targeted browsing with goats has been proven as an effective control method on some juniper species; however, little is known about its ability to control ERC. These studies intend to mend knowledge gaps of how targeted browsing with goats control ERC by causing tree death without chemicals or machinery. The first study is two 3x3 Latin squares comparing protein-supplemented diets. The second study is a randomized complete block design of five 0.224 ha …

The Potential Of Bison Restoration As An Ecological Approach To Future Tribal Food Sovereignty On The Northern Great Plains, Hila Shamon, Olivia G. Cosby, Chamois L. Andersen, Helen Augare, Jony Bearcub Stiffarm, Claire E. Bresnan, Jeff M. Martin, Et Al.

Natural Resource Management Faculty Publications

Future climate projections of warming, drying, and increased weather variability indicate that conventional agricultural and production practices within the Northern Great Plains (NGP) will become less sustainable, both ecologically and economically. As a result, the livelihoods of people that rely on these lands will be adversely impacted. This is especially true for Native American communities, who were relegated to reservations where the land is often vast but marginal and non-tribal operators have an outsized role in food production. In addition, NGP lands are expected to warm and dry disproportionately relative to the rest of the United States. It is therefore …

Essays On Conservation Outcomes On Rented Farmland: Role Of Gender, Diya Ganguly

Department of Agricultural Economics: Dissertations, Theses, and Student Research

The essays in this dissertation explore why female landowners may be less likely than male landowners to achieve long term conservation on their land. In Chapter 1 we develop theory to model the strategic interaction between a landowner and a tenant with a focus on their gender and implementation of conservation practices on land. Within the context of a sequential-move game, we use the principal-agent framework and identity theory to model land-use choice and equilibrium payoffs between landowner and tenant. We consider cash rent lease and discounted lease whereby the tenant pays a reduced rent if they implement conservation practices …

Collected Papers (On Neutrosophics Theory And Applications), Volume Xii, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

This twelfth volume of Collected Papers includes 86 papers comprising 976 pages on Neutrosophic Theory and Applications, published between 2013-2021 in the international journal and book series NSS by the author alone or in collaboration with the following 112 co-authors (alphabetically ordered) from 21 countries.

Studies Of Electromagnetic Counterparts To Gravitational-Wave Sources And The Nonlinear Gravitational-Wave Memory Effect, Ashok Choudhary

Graduate Theses, Dissertations, and Problem Reports (ETD)

In this dissertation, theoretical/computational results are presented from the investigations of three different topics within the general research areas of gravitational wave astrophysics and electromagnetic counterparts. First, general relativistic force-free electromagnetic theory and its application to black hole magnetospheres are discussed. In this connection, simulations of a binary black hole merger are examined using the open-source software, GiRaFFE, which is used to model black holes’ magnetospheres and to study supermassive black-hole binary mergers in an external magnetic field. In the simulations, a helical magnetic field structure around each black hole is observed. Electromagnetic energy flux is observed during the inspiral …

Polychromatic Colorings Of Certain Subgraphs Of Complete Graphs And Maximum Densities Of Substructures Of A Hypercube, Ryan Tyler Hansen

Graduate Theses, Dissertations, and Problem Reports (ETD)

If G is a graph and H is a set of subgraphs of G, an edge-coloring of G is H-polychromatic if every graph from H gets all colors present in G on its edges. The H-polychromatic number of G, poly_HG, is the largest number of colors in an H-polychromatic coloring. We determine poly_HG exactly when G is a complete graph on n vertices, q a fixed nonnegative integer, and H is the family of one of: all matchings spanning n-q vertices, all 2-regular graphs spanning at least n-q vertices, or all cycles of length precisely n-q. …

Pathfinding Fast Radio Bursts Localizations Using Very Long Baseline Interferometry, Pranav Rohit Sanghavi

Graduate Theses, Dissertations, and Problem Reports (ETD)

Fast radio bursts (FRBs) are millisecond-duration, bright radio transients of extragalactic origin. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope’s CHIME/FRB instrument and other radio telescopes across the globe have detected hundreds of FRBs. Their origins are a mystery. Precise localization within the host is critical to distinguish between progenitor models. This can be achieved through Very Long Baseline Interferometry (VLBI). Until now, VLBI localizations have only been carried out in targeted follow-up observations of some repeating sources which comprise a small fraction of the FRBs.

For this work, an interferometric array of 6m dishes was constructed at the Green …

A Workflow For Unconventional Reservoirs Optimization Using Supervised Machine Learning In Conjunction With Orthorhombic Elasticity Modeling, Aymen Ab Ali Alhemdi

Graduate Theses, Dissertations, and Problem Reports (ETD)

Due to the anisotropy and heterogeneous nature of unconventional reservoirs like shale, a comprehensive parametric study to optimize hydraulic fracture treatment for such reservoirs is a tough challenge, especially when natural fractures are present. Most of the current frac simulators do not consider the anisotropy of rock elasticity in the shales. Besides, using the fracture simulation linked with reservoir simulation for the parametric study to understand the impact of multiple different design parameters on fracture propagation and production is time expensive and low efficient. The study proposes a workflow including a new orthorhombic (OB) rock algorithm to interpret geomechanical properties …

Identifying And Minimizing Sources Of Variability Within Modern Spectroscopic Techniques For The Forensic Analysis Of Glass, Oriana Christy Ovide

Graduate Theses, Dissertations, and Problem Reports (ETD)

Broken glass is a trace material frequently found at crime scenes such as hit-and-runs, burglaries, assaults, and homicides. Existing research encompassing the forensic analysis of glass evidence is vast. Published studies cover the analysis and interpretation of various types of glass. However, organizations such as the National Institute of Justice (NIJ), National Institute of Standards and Technology Organization of Scientific Area Committees (NIST-OSAC), and American Society of Trace Evidence Examiners (ASTEE) continue to identify glass-specific research needs to strengthen the scientific foundations of the field. Current gaps within the forensic glass community involve understanding modern glass formulations, re-evaluating the performance …

Synthesis And Cyclotrimerization Of Sulfonyl Enynes, Alexa C. Martin

Graduate Theses, Dissertations, and Problem Reports (ETD)

The synthesis of complex, polysubstituted aromatic rings from simple, non-aromatic building blocks is a consistent challenge to the synthetic community. Neopentylene ring fusions are found in several natural products but are largely absent from synthetic compound libraries. This discrepancy reflects the limitations in modern chemical synthesis. Utilizing, in part, a thoroughly developed fragmentation/olefination methodology from the Dudley Lab, a library of novel 1-sulfonyl-1,6-enynes have been developed. In this methodology, they are prepared in three steps from dimedone (5,5-dimethyl-1,3-cyclohexanedione), an inexpensive starting material. A total of 14 novel 1-sulfonyl-1,6-enynes were synthesized. These substrates were subjected to a novel benzannulation reaction based …

Discussing Changes In Historical Human–Environmental Dynamics Through Ecosystem Services Interactions And Future Scenarios In A Rural-Mining Region Of Central Appalachians, Vincenzo Cribari

Graduate Theses, Dissertations, and Problem Reports (ETD)

The aim of this dissertation was to investigate how recent processes of land-change induced by humans contributed to the shaping and alteration of the current landscape in a headwater system of Central Appalachians in West Virginia (US), to understand the interactions and tradeoffs among ecosystems services and address potential solutions for targeting more sustainable human-environment interactions in a region that is deeply grounded on extractive economies. The multitiered objective was addressed through different research phases in order to unfold and disentangle a series of complex problems that the study area presents. Three main phases were used; they corresponded to distinct …

Colonial Markets, Consumers, And Trade: A Comparative Analysis Of Historic Ceramics From The Bluefields Bay Area, Westmoreland, Jamaica, Lacy Risner

Murray State Theses and Dissertations

The ceramic assemblages from a British colonial settlement in Bluefields Bay, Jamaica, provide a unique window into the market availability, exchange routes, and consumption patterns of the eighteenth century. This study compares the historic ceramics collected from two sites in Bluefields Bay to one another and to other intra-island (Jamaica), intraregional (Lesser Antilles), and international (North America) colonial and postcolonial sites to reveal patterns of individual and global ceramic consumption and distribution in the emergent capitalist networks and markets of the colonial era. Integrating small British colonial sites into the networks of other more extensive studies focusing primarily on plantations …

Heterogeneous Oxidation Of Multi-Component Aqueous Organic Aerosols: The Effect Of Transport Phenomena And Reaction Compartment On Reaction Kinetics., Tadini Wenyika Masaya

Graduate Theses, Dissertations, and Problem Reports (ETD)

The surface-bulk partitioning of small organic molecules in aqueous droplets was investigated using molecular dynamics. The air-particle interface was modeled using a 80-Å cubic water box containing series of organic molecules and surrounded by gaseous OH radicals. The properties of the organic solutes within the interface and the water-bulk were examined at a molecular-level using density profiles and radial pair distribution functions. Molecules containing only polar functional groups such as urea and glucose are found predominantly in the water bulk, forming an exclusion layer near the water surface. Substitution of a single polar group by an alkyl group in sugars …

Microwave Enhanced Electron Energy Distribution Functions, John Samuel Mckee

Graduate Theses, Dissertations, and Problem Reports (ETD)

The use of two (or more) radio frequency (RF) sources at different frequencies is a common technique in the plasma processing industry to control ion energy characteristics separately from plasma generation. A similar approach is presented here with the focus on modifying the electron population in argon and helium plasmas. The plasma is generated by a helicon source at a frequency f0 = 13.56 MHz. Microwaves of frequency f1 = 2.45 GHz are then injected into the helicon source chamber perpendicular to the background magnetic field. The microwaves damp on the electrons via R-mode (anti-parallel to the background magnetic field …

Structure-Dependent Characterizations Of Multistationarity In Mass-Action Reaction Networks, Galyna Voitiuk

Graduate Theses, Dissertations, and Problem Reports (ETD)

This project explores a topic in Chemical Reaction Network Theory. We analyze networks with one dimensional stoichiometric subspace using mass-action kinetics. For these types of networks, we study how the capacity for multiple positive equilibria and multiple positive nondegenerate equilibria can be determined using Euclidian embedded graphs. Our work adds to the catalog of the class of reaction networks with one-dimensional stoichiometric subspace answering in the affirmative a conjecture posed by Joshi and Shiu: Conjecture 0.1 (Question 6.1 [26]). A reaction network with one-dimensional stoichiometric subspace and more than one source complex has the capacity for multistationarity if and only …

Scaling Theory Of 3d Magnetic Reconnection X-Line Spreading, Milton Arencibia

Graduate Theses, Dissertations, and Problem Reports (ETD)

Magnetic reconnection is fundamental process in plasmas that converts magnetic energy into kinetic and thermal energy via a change in magnetic topology. Magnetic reconnection is known to mediate eruptive solar flares, geomagnetic substorms that create the Northern lights, heating and particle acceleration in controlled fusion devices, and is thought to be an important process in numerous settings in high-energy astrophysics. Classical models of reconnection are two-dimensional (2D), but naturally occurring reconnection is three-dimensional (3D), and a manifestation of the 3D nature is that the x-line where the magnetic field topology changes has a finite extent in the direction normal to …

Planar Chiral Metasurfaces With Maximal And Tunable Chiroptical Response Driven By Bound States In The Continuum, Tan Shi, Zi-Lan Deng, Guangzhou Geng, Xianzhi Zeng, Yixuan Zeng, Guangwei Hu, Adam Overvig, Junjie Li, Cheng-Wei Qiu, Andrea Alù, Yuri S. Kivshar, Xiangping Li

Advanced Science Research Center

Optical metasurfaces with high quality factors (Q-factors) of chiral resonances can boost substantially light-matter interaction for various applications of chiral response in ultrathin, active, and nonlinear metadevices. However, current approaches lack the flexibility to enhance and tune the chirality and Q-factor simultaneously. Here, we suggest a design of chiral metasurface supporting bound state in the continuum (BIC) and demonstrate experimentally chiroptical responses with ultra-high Q-factors and near-perfect circular dichroism (CD = 0.93) at optical frequencies. We employ the symmetry-reduced metaatoms with high birefringence supporting winding elliptical eigenstate polarizations with opposite helicity. It provides a convenient way for achieving the maximal …

Reciprocity Of Thermal Diffusion In Time-Modulated Systems, Jiaxin Li, Ying Li, Pei-Chao Cao, Minghong Qi, Xu Zheng, Yu-Gui Peng, Baowen Li, Xue-Feng Zhu, Andrea Alù, Hongsheng Chen, Cheng-Wei Qiu

Advanced Science Research Center

The reciprocity principle governs the symmetry in transmission of electromagnetic and acoustic waves, as well as the diffusion of heat between two points in space, with important consequences for thermal management and energy harvesting. There has been significant recent interest in materials with time-modulated properties, which have been shown to efficiently break reciprocity for light, sound, and even charge diffusion. However, time modulation may not be a plausible approach to break thermal reciprocity, in contrast to the usual perception. We establish a theoretical framework to accurately describe the behavior of diffusive processes under time modulation, and prove that thermal reciprocity …

Coherent Full Polarization Control Based On Bound States In The Continuum, Ming Kang, Ziying Zhang, Tong Wu, Xueqian Zhang, Quan Xu, Alex Krasnok, Jiaguang Han, Andrea Alù

Advanced Science Research Center

Bound states in the continuum (BICs) are resonant modes of open structures that do not suffer damping, despite being compatible with radiation in terms of their momentum. They have been raising significant attention for their intriguing topological features, and their opportunities in photonics to enhance light-matter interactions. In parallel, the coherent excitation of optical devices through the tailored interference of multiple beams has been explored as a way to enhance the degree of real-time control over their response. Here, we leverage the combination of these phenomena, and exploit the topological features of BICs in the presence of multiple input beams …

Fast Encirclement Of An Exceptional Point For Highly Efficient And Compact Chiral Mode Converters, Xiaoqian Shu, Aodong Li, Guangwei Hu, Jian Wang, Andrea Alù, Lin Chen

Advanced Science Research Center

Exceptional points (EPs) are degeneracies at which two or more eigenvalues and eigenstates of a physical system coalesce. Dynamically encircling EPs by varying the parameters of a non- Hermitian system enables chiral mode switching, that is, the final state of the system upon a closed loop in parameter space depends on the encircling handedness. In conventional schemes, the parametric evolution during the encircling process has to be sufficiently slow to ensure adiabaticity. Here, we show that fast parametric evolution along the parameter space boundary of the system Hamiltonian can relax this constraint. The proposed scheme enables highly efficient transmission and …