Optics Commons^™

Rapid-Prototyping Nanofabrication: Lcd-Based Projection Lithography And Physical Vapor Deposition, Sabeel Saleem Mohammmed

University Honors Theses

The semiconductor industry's continued growth, driven in large part by demand for artificial intelligence hardware, has highlighted the need for greater workforce development in regions adjacent to major fabrication centers like Oregon's Silicon Forest. This capstone project lays the groundwork for a small scale and student led semiconductor fabrication lab at Portland State University by demonstrating two of the core steps in chip manufacturing: photolithography and thin film deposition. Rather than relying on conventional fixed reticles, this work explores a unique, low cost approach to patterning that uses an ultraviolet-compatible liquid crystal display (LCD) as a programmable reticle, allowing arbitrary …

Sensing Negative-Cone Rotational Diffusion Of Dipole-Like Emitters, Yuanxin Qiu, Kaizhi A. Nie, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

Fluorescence anisotropy and single-molecule orientation-localization microscopy (SMOLM) are powerful techniques that quantify the rotational diffusion of dipole-like emitters, which is important for sensing molecular interactions and chemical environments at the nanoscale. Numerous theoretical and experimental studies have thoroughly characterized single-molecule rotations even when those rotations are much faster than the detector integration time. Here, we extend the theory of measuring rotational diffusion to situations where a single dipole rotates uniformly everywhere outside of an isotropic cone of a certain size, termed a negative cone. This scenario corresponds to negative fluorescence anisotropy 𝑟 and has been observed in emitters exhibiting strong …

Impact Of Ethanol On The Evolution Of One-Step Synthesized Gold Nanoplates And Nanostars And Their Effects On Raman Signal Enhancement, Ananda Fania, Nonni Soraya Sambudi, Kirana Yuniati Putri, Yuliati Herbani, Affi Nur Hidayah

Makara Journal of Science

Gold nanoplates and nanostars were synthesized from a gold metal salt solution (HAuCl₄) using a one-step synthesis method of ultraviolet C (UVC) light irradiation. The gold salt solution was mixed with ethanol in 6 mL with the following ratios: (1.5:4.5, 3:3, and 4.5:1.5), and subsequently irradiated with UVC light. Changes in localized surface plasmon resonance (LSPR) shifts were observed in real time at 30-min intervals for 2 h. The synthesis process produces gold nanoplates. While gold nanostars were synthesized from a solution of gold salt combined with ethanol, ascorbic acid, and AgNO₃, maintaining a consistent ratio …

Plasmonic Nanoparticle Integration On Fiber Optic: Role Of Organic Linker And Functionalization Length In Refractive Index Sensing, Shela Ilmiyah, Mohamad Syahadi, Muflikhah Muflikhah, Yuwana Pradana, Zainul Arifin Iman Supardi, Iwan Darmadi, Lia Aprilia

Makara Journal of Science

Nanoplasmonic fiber optic sensors leverage the optical fiber’s inherent compactness and surface sensitivity via evanescent-field interactions with the localized surface plasmon resonance of the metallic nanoparticles. One of the popular approaches is self-assembly owing to its relatively low cost. Despite its low cost, the self-assembly technique has low reproducibility and exhibits low sensitivity because of low nanoplasmonic coverage on the fiber optic surface. In this study, several fabrication techniques were explored to assess the refractive index sensitivity by comparing three common organosilanes, i.e., (3-Aminopropyl)triethoxysilane (APTES), (3-Aminopropyl)trimethoxysilane, and (3-Mercaptopropyl)trimethoxysilane. Comparative analyses assessed the anchoring efficiency of the three silanes, sensor reproducibility, …

Single-Molecule Orientation And Localization Microscopy, Sophie Brasselet, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

Single-molecule localization microscopy (SMLM) offers enhanced spatial resolution in optical microscopy, providing detailed insights into the spatial organization of proteins in cells at the nanoscale. Over the past decade, SMLM has progressively incorporated the capability to retrieve the orientations of single molecules using their polarized dipolar emission pattern. Here we explore recent advancements in single-molecule orientation and localization microscopy (SMOLM), which yields super-resolved images of molecular three-dimensional (3D) orientations, wobble and 3D positions. This advancement opens possibilities to explore the nanoscale organization and conformation of biological molecules as well as to monitor and design local 3D optical fields in nanophotonics. …

Single-Molecule Orientation Imaging Reveals The Nano-Architecture Of Amyloid Fibrils Undergoing Growth And Decay, Brian Sun, Tianben Ding, Weiyan Zhou, Tara S. Porter, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

Amyloid-beta (Aβ42) aggregates are characteristic Alzheimer’s disease signatures, but probing how their nanoscale architectures influence their growth and decay remains challenging using current technologies. Here, we apply time-lapse single-molecule orientation-localization microscopy (SMOLM) to measure the orientations and rotational “wobble” of Nile blue (NB) molecules transiently binding to Aβ42 fibrils. We correlate fibril architectures measured by SMOLM with their growth and decay over the course of 5 to 20 min visualized by single-molecule localization microscopy (SMLM). We discover that stable Aβ42 fibrils tend to be well-ordered and signified by well-aligned NB orientations and small wobble. SMOLM also shows that increasing order …

Crystalline Colloidal Arrays: Exploring Light-Matter Interactions, Haley W. Jones

All Dissertations

Understanding and manipulating quantum light-matter interactions, especially in the context of nanostructured environments, is highly critical for technological progress and inventive solutions in the fields of telecommunications, energy-efficient lighting, and cutting-edge quantum computing technologies. The fundamental interactions of photons with a surrounding environment directly impact the performance and efficiency of devices such as lasers, light-emitting diodes (LEDs), and quantum computing elements, which leverage the unique properties of confined structured environments. Since the late 1980s, the connection between a structured environment and the decay kinetics of an embedded fluorophore has been a highly debated and unresolved topic in the literature. More …

6d Single-Fluorogen Orientation-Localization Microscopy For Elucidating The Architecture Of Beta-Sheet Assemblies And Biomolecular Condensates, Tingting Wu, Weiyan Zhou, Jai S. Rudra, Rohit V. Pappu, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

We develop six-dimensional single-molecule orientation-localization microscopy (SMOLM) to measure the 3D positions and 3D orientations simultaneously of single fluorophores. We show how careful optimization of phase and polarization modulation components can encode phase, polarization, and angular spectrum information from each fluorescence photon into a microscope’s dipole-spread function. We used the transient binding and blinking of Nile red (NR) to characterize the helical structure of fibrils formed by designed amphipathic peptides, KFE8^L and KFE8^D, and the pathological amyloid-beta peptide Aβ42. We also deployed merocyanine 540 to uncover the interfacial architectures of biomolecular condensates.

Tunable Linear And Nonlinear Metasurfaces Based On Hybrid Gold-Graphene Plasmons, Matthew Feinstein

Dissertations, Theses, and Capstone Projects

Optical Metasurfaces are planar structures that are patterned with subwavelength structures and are very thin compared to the wavelength of light. Despite their thinness, these structured materials can strongly interact with incident light to effect the functionalities of conventional optical components, such as rotation of the polarization state, beam steering, lensing, spectral filtering, and holography, to name a few. Metasurfaces can also facilitate nonlinear optical effects, such as the mixing of beams at different frequencies to generate a beam at a new frequency.

The ability to alter the behavior of a metasurface during operation is highly desired for applications such …

Six-Dimensional Single-Molecule Imaging With Isotropic Resolution Using A Multi-View Reflector Microscope, Oumeng Zhang, Zijian Guo, Yuanyuan He, Tingting Wu, Michael D. Vahey, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

Imaging of both the positions and orientations of single fluorophores, termed single-molecule orientation-localization microscopy, is a powerful tool for the study of biochemical processes. However, the limited photon budget associated with single-molecule fluorescence makes high-dimensional imaging with isotropic, nanoscale spatial resolution a formidable challenge. Here we realize a radially and azimuthally polarized multi-view reflector (raMVR) microscope for the imaging of the three-dimensional (3D) positions and 3D orientations of single molecules, with precisions of 10.9 nm and 2.0° over a 1.5-μm depth range. The raMVR microscope achieves 6D super-resolution imaging of Nile red molecules transiently bound to lipid-coated spheres, accurately resolving …

Subwavelength Engineering Of Silicon Photonic Waveguides, Farhan Bin Tarik

All Dissertations

The dissertation demonstrates subwavelength engineering of silicon photonic waveguides in the form of two different structures or avenues: (i) a novel ultra-low mode area v-groove waveguide to enhance light-matter interaction; and (ii) a nanoscale sidewall crystalline grating performed as physical unclonable function to achieve hardware and information security. With the advancement of modern technology and modern supply chain throughout the globe, silicon photonics is set to lead the global semiconductor foundries, thanks to its abundance in nature and a mature and well-established industry. Since, the silicon waveguide is the heart of silicon photonics, it can be considered as the core …

Observation And Control Of Photoemission And Electric Field Enhancement Of Plasmonic Antennas Through Photoemission Electron Microscopy, Christopher M. Scheffler

Dissertations and Theses

Photoemission electron microscopy (PEEM) is an imaging method which uses electrons excited through the photoelectric effect to characterize a sample surface with nanometer-level resolution. In PEEM, a high intensity laser excites electrons from the surface of the material and electron optics are used to form an image from the intensity and spatial distribution of the photoemission from the sample. The goal of this research was to study and maximize light confinement, which was accomplished using plasmonic nanostructures. Surface plasmons represent oscillations in the electron density of a material and can occur along the transition interface between a metal and a …

Monolithically Integrated Microscale Pressure Sensor On An Optical Fiber Tip, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) pressure sensor includes an optical fiber and a three-dimensional microscopic optical enclosure. The three-dimensional microscopic optical enclosure includes tubular side walls having lateral pleated corrugations and attached to a cleaved tip of the optical fiber to receive a light signal. An optically reflecting end wall is distally engaged to the tubular side walls to enclose a trapped quantity of gas that longitudinally positions the optically reflecting end wall in relation to ambient air pressure, changing a distance traveled by a light signal reflected back through the optical fiber.

Hinged Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor includes a three-dimensional microscopic optical structure formed on a cleaved tip of the optical fighter using a two-photon polymerization process on a photosensitive polymer by a three-dimensional micromachining device. The three-dimensional microscopic optical structure having a hinged optical layer pivotally connected to a distal portion of a suspended structure. A reflective layer is deposited on a mirror surface of the hinged optical layer while in an open position. The hinged optical layer is subsequently positioned in the closed position to align the mirror surface to at least partially reflect a light signal back …

Method Of Making Hinged Self-Referencing Fabry–Pérot Cavity Sensors, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A method is provided for fabricating a passive optical sensor on a tip of an optical fiber. The method includes perpendicularly cleaving a tip of an optical fiber and mounting the tip of the optical fiber in a specimen holder of a photosensitive polymer three-dimensional micromachining machine. The method includes forming a three-dimensional microscopic optical structure within the photosensitive polymer that comprises a two cavity Fabry-Perot Interferometer (FPI) having a hinged optical layer that is pivotally coupled to a suspended structure. The method includes removing an uncured portion of the photosensitive polymer using a solvent. The method includes depositing a …

Exploring Magneto-Excitons In Bulk And Mono-Layer Semiconductors Using Non-Linear Spectroscopy Techniques, Varun Mapara

USF Tampa Graduate Theses and Dissertations

The research in two-dimensional (2D) materials has evolved from ``traditional" quantum wells based on group III-V and II-VI semiconductors to atomically thin sheets of van der Waals materials such as 2D semiconducting Transition Metal Dichalcogenides (TMDs). These 2D materials remain a stimulating field that continues to introduce new challenges. From both a fundamental physics and technological perspective, magneto-optical spectroscopy has been an essential tool in this research field. TMDs, for example, pose the challenge of characterizing their spin-valley-resolved physics and deriving implications in quantum computation and information research. With the discovery of valley Zeeman effects, the spin-valley physics of TMDs …

Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor an optical fiber a three-dimensional microscopic optical structure formed on a cleaved tip of an optical fighter that reflects a light signal back through the optical fiber. The reflected light is altered by refractive index changes in the three-dimensional structure that is subject to at least one of: (i) thermal radiation; and (ii) volatile organic compounds.

Interferometric Lithography- An Approach To Large Area And Cost Effective Nanopatterning, Vineeth Sasidharan

Optical Science and Engineering ETDs

In this dissertation interferometric lithography is approached in two different ways to address two important constraints of nanopatterning. One approach solves the problem of scaling up interferometric lithography to wafer scale (4 inch or larger) area. Through the second approach we have developed a nanopatterning technique based on interferometric lithography by using an inexpensive (~$100) diode laser as source, making interferometric lithography a very cost-effective technique.

Wafer-scale large-area nanopatterning was developed using an amplitude grating mask as a grating beam splitter along with spatial averaging of laser intensity by wobbling. The longitudinal and transverse coherence issues both are eased by …

Method Of Making Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith

AFIT Patents

A method of making passive microscopic Fabry-Pérot Interferometer (FPI) sensor includes forming a three-dimensional microscopic optical structure on a cleaved tip of an optical fiber that reflects a light signal back through the optical fiber. The reflected light is altered by refractive index changes in the three-dimensional structure that is subject to at least one of: (i) thermal radiation; and (ii) volatile organic compounds.

Simulation Of Light Propagation Captured By Photoemission Electron Microscopy (Peem), Nabila Islam

Dissertations and Theses

The Photoemission electron microscopes (PEEM) is a powerful tool capable of synchronously imaging wave nature of light manifested by interference patterns as well as its particle nature through the energy exchange between the incident photons and the photoemitted imaging electrons. PEEM offers a non-invasive high-resolution approach for studying light propagation and interaction phenomena within a nanophotonic waveguide [7,8]. The electric field intensity variation of the interference pattern yielded by the interaction between the incident light and the guided mode coupled into the waveguide produces varying photoemission yields creating contrast in PEEM image. The guided modes cannot be excited simply by …

Fabrication And Characterization Of Photodetector Devices Based On Nanostructured Materials: Graphene And Colloidal Nanocrystals, Wafaa Gebril

Graduate Theses and Dissertations

Photodetectors are devices that capture light signals and convert them into electrical signals. High performance photodetectors are in demand in a variety of applications, such as optical communication, security, and environmental monitoring. Among many appealing nanomaterials for novel photodetection devices, graphene and semiconductor colloidal nanocrystals are promising candidates because of their desirable and unique properties compared to conventional materials.

Photodetector devices based on different types of nanostructured materials including graphene and colloidal nanocrystals were investigated. First, graphene layers were mechanically exfoliated and characterized for device fabrication. Self-powered few layers graphene phototransistors were studied. At zero drain voltage bias and room …

Optical Properties Of Ultrathin In(Ga)As/Gaas And In(Ga)N/Gan Quantum Wells, Yurii Maidaniuk

Graduate Theses and Dissertations

Recently, structures based on ultrathin quantum wells (QWs) began to play a critical role in modern devices, such as lasers, solar cells, infrared photodetectors, and light-emitting diodes. However, due to the lack of understanding of the formation mechanism of ultrathin QWs during the capping process, scientists and engineers cannot fully explore the potential of such structures. This study aims to investigate how structural parameters of ultrathin QWs affect their emission properties by conducting a systematic analysis of the optical properties of In(Ga)As/GaAs and In(Ga)N/GaN ultrathin QWs. Specifically, the analysis involved photoluminescence measurements combined with effective bandgap simulation, x-ray diffraction, and …

Designing A Reactor Chamber For Hot Electron Chemistry On Bimetallic Plasmonic Nanoparticles, Bryn Merrill, Bingjie Zhang, Jerry Larue

SURF Posters and Papers

Catalysis provides pathways for efficient and selective chemical reactions by lowering the energy barriers for desired products. Gold nanoparticles (AuNPs) show excellent promise as plasmonic catalysts. Plasmonic materials have localized surface plasmon resonances, oscillations of the electron bath at the surface of a nanoparticle, that generate energetically intense electric fields which rapidly decay into energetically excited electrons. The excited electrons have the potential to destabilize atoms strongly bound to the catalysts through occupation of antibonding orbitals. Tuning the antibonding orbitals to make them accessible for occupancy by electrons is achieved by coating the AuNP in a thin layer of another …

Investigation Of Complex Refractive Index Of Grad Phene Oxide Using Polarisation Response Of Graphene Oxide-Coated Planarizeoptical Waveguide, Soon Xin Gan

Student Works (2020-2029)

Since a single atomic layer of carbon, also as known as graphene is being successfully exfoliated from 3D graphite, intense research on graphene and its derivative begins. Among them, graphene oxide (GO) is considered one of the most prominent candidates in the category of graphene derivatives for the application of electronic, optoelectronic and photonics. However, although GO has been applied in many applications like saturable absorbers of Q-switch laser and optical limiters for eye protection, its intrinsic optical properties especially complex refractive index reported so far still has a large deviation. Also, most of the optical characterization research on GO …

In-Situ Gold-Ceria Nanoparticles: Superior Optical Fluorescence Quenching Sensor For Dissolved Oxygen, Nader Shehata, Ishac Kandas, Effat Samir

Electrical & Computer Engineering Faculty Publications

Cerium oxide (ceria) nanoparticles (NPs) have been proved to be an efficient optical fluorescent material through generating visible emission (~530 nm) under violet excitation. This feature allowed ceria NPs to be used as an optical sensor via the fluorescence quenching Technique. In this paper, the impact of in-situ embedded gold nanoparticles (Au NPs) inside ceria nanoparticles was studied. Then, gold–ceria NPs were used for sensing dissolved oxygen (DO) in aqueous media. It was observed that both fluorescence intensity and lifetime were changed due to increased concentration of DO. Added gold was found to enhance the sensitivity of ceria to DO …

Nanoscale Colocalization Of Fluorogenic Probes Reveals The Role Of Oxygen Vacancies In The Photocatalytic Activity Of Tungsten Oxide Nanowires, Meikun Shen, Tianben Ding, Steven T. Hartman, Fudong Wang, Christina Krucylak, Zheyu Wang, Che Tan, Bo Yin, Rohan Mishra, Matthew D. Lew, Bryce Sadtler

Electrical & Systems Engineering Publications and Presentations

Defect engineering is a strategy that has been widely used to design active semiconductor photocatalysts. However, understanding the role of defects, such as oxygen vacancies, in controlling photocatalytic activity remains a challenge. Here, we report the use of chemically triggered fluorogenic probes to study the spatial distribution of active regions in individual tungsten oxide nanowires using super-resolution fluorescence microscopy. The nanowires show significant heterogeneity along their lengths for the photocatalytic generation of hydroxyl radicals. Through quantitative, coordinate-based colocalization of multiple probe molecules activated by the same nanowires, we demonstrate that the nanoscale regions most active for the photocatalytic generation of …

Tunable-Focus Liquid Lens Through Charge Injection, Shizhi Qian, Wenxiang Shi, Huai Zheng, Zhaohui Liu

Mechanical & Aerospace Engineering Faculty Publications

Liquid lenses are the simplest and cheapest optical lenses, and various studies have been conducted to develop tunable-focus liquid lenses. In this study, a simple and easily implemented method for achieving tunable-focus liquid lenses was proposed and experimentally validated. In this method, charges induced by a corona discharge in the air were injected into dielectric liquid, resulting in “electropressure” at the interface between the air and the liquid. Through a 3D-printed U-tube structure, a tunable-focus liquid lens was fabricated and tested. Depending on the voltage, the focus of the liquid lens can be adjusted in large ranges (−∞ to −9 …

Sequence-Coded Coherent Laser Ranging With High Detection Sensitivity, Keren Shemer, Gil Bashan, H Hagai Diamandi, Yosef London, Tzur Raanan, Yochai Israelashvili, Alon Charny, Itzik Cohen, Arik Bergman, Nadav Levanon, Avi Zadok

Advanced Science Research Center

The compression of extended, coded sequences allows for laser ranging measurements with low peak power levels. Previous realizations of this approach were restricted by additive noise of direct, incoherent detection. In this work we bring together pulse sequence coding and optical coherent detection to achieve very high sensitivity. Collected sequences with an overall energy equivalent to only 800 photons are successfully compressed. The observed sensitivity agrees with analytic predictions. Compared with incoherent detection, measurement durations are reduced by four orders of magnitude. The protocol is suitable for laser ranging over tens of kilometers, depending on atmospheric conditions.

Modification Of The Optical Response Of Alpha Quartz Via The Deposition Of Gold Nanoparticles In Etched Ion Tracks, Maria C. Garcia Toro

Doctoral Dissertations

”This study addresses the experimental methods used to develop and characterize plasmonic devices capable of modifying the optical response of alpha quartz via the deposition of gold nanoparticles in etched ion tracks. In the first part of the research, the microstructural characterization of latent and etched ion tracks produced in alpha quartz (α-SiO₂) is presented. Single crystals of α-SiO₂ were irradiated with two highly energetic ions to different nominal fluences. As expected, the morphology of the resulting ion tracks depends on the energy of the incident ion and their stopping powers within the target material. Subsequent chemical …

Near-Field And Far-Field Microscopic And Spectroscopic Characterizations Of Coupled Plasmonic, Excitonic And Polymeric Materials, Chih-Feng Wang

Optical Science and Engineering ETDs

The properties of localized surface plasmons (LSP) have been broadly utilized for chemical sensing, surface enhanced Raman spectroscopy, biomedical imaging and photothermal treatments. By exploiting well-established plasmonic effects, the spectroscopic investigation of intriguing quantum phenomena, such as excitonic interband and intersubband (ISB) transitions in semiconductor heterostructures, was examined and extended in both far- and near-field optical measurements. For far-field characterization, we used colloidal plasmonic Au nanorods (AuNRs) to increase the quantum efficiency of InGaAs/GaAs single quantum well. By analyzing the temperature-dependent photoluminescence enhancement as a function of GaAs capping layer thickness, we attributed the mechanism of the LSP enhancement to …