Optical Devices  |  Electron Optics  |  Imaging Systems  |   Fiber Optics

10:10 am Optical Devices

10:10 2nd generation acousto-optic deflector based laser drilling

Jan Kleinert – ESI

As available laser power continues to grow exponentially, laser beam positioning is increasingly becoming the bottleneck in micromachining tool productivity. While splitting the laser into multiple heads or systems mitigates this somewhat, this alone doesn’t necessarily suffice. Acousto-optic deflectors provide a different way to scale processing speeds than polygon scanners due to their non-mechanical nature. The first generation of AOD based tools provided higher bandwidth positioning speeds, the second generation now enables processes that are not quite possible without them.

10:25 Quantum Pulse Gating via Nonlinear Frequency Conversion

Dileep Reddy – University of Oregon

Temporal modes (TM) are a burgeoning basis for storage and manipulation of classical and quantum information in light. Creation of TM selective, high-fidelity devices are essential for characterization and design of systems that can exploit this degree of freedom. A crucial technology on this front is the quantum pulse gate (QPG), a programmable device that can unitarily multiplex/demultiplex specific TM components in a pulsed field. We present the theoretical basis for the selectivity barrier that plague high efficiency QPGs, propose the first, and thus far, only means of overcoming said barrier via cascaded setups and interferometric techniques, and showcase experimental results for our QPG implementation using second-order nonlinear waveguides.

10:40 High-Speed Wide-Angle Optical Transmitter and Receiver for Indoor Hybrid Free-Space Optical and WiFi Networks

Spencer Liverman – Oregon State University

Free-space optical (FSO) networks have recently been explored as an alternative to traditional WiFi due to their large bandwidth potentials and low interference. In this work, we present a FSO transmitter and receiver pair to be used in an indoor WiFO network. The FSO transmitter described in this work uses low-cost, high power near-infrared light emitting diodes and the FSO receiver is built based on an off-the- shelf photodetector and transimpedance amplifier. The FSO system is capable of transmitting and receiving data at a rate of 60Mbit/s and covers a distance of up to three meters with a field-of- view of ±30˚, while still achieving a low bit error rate between 10^-6 and 10^-4.

11:05 am Electron Optics

11:05 Optics from Light to Electrons to Ions

David Tuggle – Thermo Fisher (Formally FEI)

The basic principles of light optics were adapted to particle optics starting in the 1920s. From cathode ray oscilloscopes to transmission electron microscopes, field emission and ion microscopes, scanning electron microscopes and ebeam lithography to focused ion beam (FIB) systems, particle optics has taken several detours from light optics into Coulomb effects (Boersch) and limitations on aberrations due to the nature of electrostatic and magnetic focusing fields (Scherzer). This talk will attempt to cover the history of these detours from light optics, from the author’s perspective of the past 40 years of involvement in point source particle optics.

11:20 Photonic Waveguide Characterization via Photoemission Electron Microscopy

Theodore Stenmark – Portland State University

Multi-photon photoemission electron microscopy (PEEM) has well documented applications for observing plasmonic and photonic phenomena using interferometric approaches. Typically a photonic or plasmonic interference pattern is created from which the dynamic propagation of the electromagnetic field is extracted. Using interference effects at the interface of optically transparent thin film dielectrics allows for characterization of light propagation in thin film optical devices. By varying the frequency of exciting photons the dispersion relation for a waveguide can be experimentally determined. Of particular interest are structures such as photonic crystal waveguides which exhibit strong dispersion in a narrow band of frequencies. This effect can be interpreted as a small group velocity or slow light effect.

11:35 Holographic Beam Shaping

Jordan Pierce – University of Oregon

Many applications utilize holographic beam shaping to encode a desired property onto a wavefront. The ability to arbitrarily control both the phase and amplitude of a scalar field (or unpolarized beam) makes holographic beam shaping very desirable. Here I show how to create off-axis holograms to reproduce any arbitrary beam up to a certain bandwidth cutoff. I show the design and manufacturing process, as well as some applications in electron beam systems. These electron holograms are currently in use in various electron microscopes to probe previously unreachable sample properties.

11:50 Confinement of Noble Metal (111) Surface Electrons by Carbon Nanohoop Quantum Corrals

Ben Taber – University of Oregon

Quantum confinement of two-dimensional surface electronic states is a possible way for controllably modifying the electronic structures of a variety of coinage metal surfaces. We present real-space scanning tunneling microscopy/spectroscopy (STM/STS) investigations of electronic confinement within individual ring-shaped cycloparaphenylene (CPP) molecules forming self-assembled films on Ag(111) and Au(111) surfaces. STM imaging and STS mapping show the presence of electronic states localized in the CPP interiors, inconsistent with the expected localization of molecular electronic orbitals. These observations are explained by the presence of localized states formed due to confinement of surface electrons by the CPP skeletal framework, which thus acts as a molecular electronic “corral”. We used a particle-in- an-elliptical- box (PIAEB) model to describe the confined surface states, correlating molecular eccentricity and confined surface state energy. These results suggest a route for controllable and scalable modification of surface electronic structure.

3:00 pm Imaging Systems

3:00 Characterization of Two-­Photon Absorption Processes

Fredrick DeArmond – Portland State University

As optical microscopy techniques continue to improve, most notably the development of super­resolution optical microscopy which garnered the Nobel Prize in Chemistry in 2014, renewed emphasis has been placed on the development and use of robust non­linear fluorescent markers. We are developing a set of tools that will lead to a systematized approach for identifying and characterizing fluorescent probes suitable for use in advanced optical microscopy techniques as well as identifying trends for their synthesis. The experimental apparatus is comprised primarily of a modified fluorescence microscope and intensity autocorrelator for measurement of the two photon fluorescence and characterization of the ultra­fast pulsed excitation source. Together they allow the us to quantitatively measure two photon absorption cross sections.

3:15 Monitoring the Intercalation of Acridine Orange Molecules into 6-Methyl Isoxanthopterin -Labeled DNA by Circular Dichroism and Single-Molecule FRET

Huiying Ji – University of Oregon

Intercalation occurs when a small molecule ligand binds between adjacent base pairs of duplex DNA, forming a sandwich-like structure. In an attempt to provide more incisive molecular approaches to understanding intercalation mechanisms, we utilize 6-MI/AO FRET pair to gain insight of local conformation change during intercalation at millisecond timescale. 6-MI is a fluorescent guanine analogue that serve as a local reporter of DNA conformational changes, while acridine orange is a well-studied DNA intercalator. Applying single-molecule FRET and linear dichroism methods developed in our group, we are using these approaches to study the roles of intermediate conformational states during the intercalation process.

3:30 Colorimetric Biosensing with Diatom Photonic Crystal Biosilica

Xianming Kong – Oregon State University

Diatoms are a type of algae that create a cell wall made of silica. This biosilica shell, called a frustule, has a porous nature that constitutes a photonic crystal-like structure. We demonstrate a substrate fabricated using diatom frustules to be used in colorimetric biosensing. Using an optical camera and microscope, we can optically detect a colorimetric change from a change in refractive index around our sensor. We use our substrates to detect immunoassay binding events between antibodies and antigens and we observe an enhancement factor of 3x due to the biosilica diatoms.

3:45 Local actuation and transduction of graphene nanomechanical drumhead motion using all-optical techniques

David Miller – University of Oregon

Graphene nanomechanical resonators currently enable room temperature measurements of zeptogram (10^-21 g) masses and attonewton (10^-18 N) forces owing to the inherently low mass of a single layer of carbon atoms. Efficient actuation and transduction of multiple mechanical modes can further enhance the ultimate sensitivity of graphene nanomechanical resonators. I will describe the all-optical techniques we use to locally pump and probe the mechanical motion of graphene drumhead resonators. We observe that the modal response is highly dependent on the location of the drive laser, which allows us to control the relative amplitudes of spectrally separated mechanical modes.

4:10 pm Fiber Optics

4:10 Fiber gratings strain sensor systems for composites and adhesive joints

Ingrid Scheel – Multnomah Falls Research

Fiber Bragg gratings (FBGs) and other fiber optic based sensors have been used to sense environmental parameters in applications including aerospace, oil and gas, civil structure health monitoring, mining, and medical. There are many benefits to using fiber optic based sensors over traditional electrical sensing methods. FBGs are immune to electromagnetic interference, high bandwidth, low loss, small, lightweight, and portable. New developments allow these physical measurements such as strain, temperature, pressure, vibration, and acoustics to be made at extremely fast speeds extending the capability of fiber optic sensors to monitor impacts and other rapid events.

4:25 Transverse-modal-instability-free Yb-doped Chirally Coupled Core fiber MOPA

Jim (Jiamin) Zhang – nLight

Narrowband and high average power fiber amplifiers are indispensable for power-scaling in coherently and spectrally combined high power laser systems. However, TMI has posed a new challenge for achieving single transverse mode in high power from fiber amplifiers. We demonstrate TMI-free, 12.5 GHz linewidth, and single-transverse mode >2 kW output power from Yb-doped dual-clad 3C fiber. Due to an effective higher-order mode suppression this TMI-threshold power in this 3C is higher compared to LMA fiber with the similar core size, geometry and operating conditions.