Optics and Electronics Seminar

Phonon Light Switches: Leveraging Vibrations to Create Actively Tunable IR Devices

Topic: 
Phonon Light Switches: Leveraging Vibrations to Create Actively Tunable IR Devices
Abstract / Description: 

Light possesses a wave nature. Phonons do too. Within the infrared portion of the spectrum, these waves have comparable energies leading to their interaction. Here, the interaction is leveraged to create tunable infrared filters that control transmission and reflection with no moving parts at the "push of a button" for applications in next generation imaging and on-chip spectroscopy. Practically, waferscale tunable infrared filters are first demonstrated by altering graphene's plasmonic dispersion using the dielectrics surrounding it resulting in gate-tunable variations (V < 10V) of reflectance by over 1 μm. These same filters are then integrated directly atop a broadband infrared detector in a proof-of-principle demonstration of a dynamically tunable pixel. Second, field induced changes in the phonons energies of lead zirconate titante (PZT) ferroelectric bilayers result in a tunable IR filter possessing high speed, latchable operation, and scalable fabrication. Taken together, the case studies highlight the utility of harnessing phonons to sculpt the spectral response of IR elements.

Date and Time: 
Thursday, February 25, 2021 - 1:30pm

AP483 Optics & Electronics Seminar presents "Large Scale Micro-/nano-photonic Materials for Energy and Sustainability"

Topic: 
Large Scale Micro-/nano-photonic Materials for Energy and Sustainability
Abstract / Description: 

Micro/nano-structured materials offer significantly new opportunities for high efficiency devices and systems for energy harvesting, conversion and storage. There is, however, a tremendous gap between the proof-of-principle demonstrations at small scale and the intrinsically large scale real-world energy systems and sustainable applications. In this talk, I will give an overview of our research and, more specifically, present our recent development on how judiciously structured photonic materials address the challenge of the tremendous power hungry for space cooling and promote photosynthesis and crop yield in greenhouses.

Date and Time: 
Monday, March 15, 2021 - 12:00pm to Tuesday, March 16, 2021 - 11:55am

AP483 Optics & Electronics Seminar presents "My Experiences and Science at the ISS"

Topic: 
My Experiences and Science at the ISS
Abstract / Description: 

Ellen Ochoa will describe her career at NASA as the first Hispanic female astronaut, a veteran of four space shuttle missions, and Director of NASA's Johnson Space Center. She will focus on building and operating the International Space Station and show a video that chronicles one of her missions to the station as well as its current configuration.


Ellen Ochoa, American engineer, former astronaut and former director of the Johnson Space Center

Date and Time: 
Monday, March 8, 2021 - 4:15pm

AP483 Optics & Electronics Seminar presents "Grating Based Differential Phase Contrast X-ray Imaging and Recent Applications to Medical Imaging"

Topic: 
Grating Based Differential Phase Contrast X-ray Imaging and Recent Applications to Medical Imaging
Abstract / Description: 

When we think of X-ray imaging, we imagine a photon view as particles are absorbed or scattered in materials. This provides the imaging contrast in many important applications such as dental, chest X-rays, airport scanners. The application of X-ray diffraction gratings enables additional contrast modalities using conventional off-the-shelf X-ray sources. Specifically, the differential phase contrast mode can provide direct access to electron density, and the dark field (fringe visibility) contrast can give texture details well below the resolution limit of the detector – opening the door to exciting imaging possibilities, for example, in lung imaging. The standard Grating Based X-ray Phase Contrast Imaging (GBXPCI) technique uses three gratings G0, G1, G2. The first grating G0 provides the partial coherence needed for X-ray interference; the second grating G1 provides the interference of waves that generates a spatially modulated set of fringes at some distance away; the final grating G2 provides the means to interrogate the fringes before the detector. We will review the basic theory, implementation challenges, and some recent developments in literature.

Date and Time: 
Monday, March 1, 2021 - 4:15pm

AP483 Optics & Electronics Seminar: Continuous measurements of biomolecules in live subjects

Topic: 
Continuous measurements of biomolecules in live subjects
Abstract / Description: 

A biosensor capable of continuously measuring specific molecules in vivo would provide a valuable window into patients' health status and their response to therapeutics. Unfortunately, continuous, real-time molecular measurement is currently limited to a handful of analytes (i.e. glucose and oxygen) and these sensors cannot be generalized to measure other analytes. In this talk, we will present a biosensor technology that can be generalized to measure a wide range of biomolecules in living subjects. To achieve this, we develop synthetic antibodies (aptamers) that change its structure upon binding to its target analyte and produce an electrochemical current or emit light. Our real-time biosensor requires no exogenous reagents and can be readily reconfigured to measure different target analytes by exchanging the aptamer probes in a modular manner. Using our real-time biosensor, we demonstrate the first closed loop feedback control of drug concentration in live animals and discuss potential applications of this technology. Finally, we will discuss methods for generating the aptamer probes which are at the heart of this biosensor technology.


This seminar is sponsored by the Department of Applied Physics and the Ginzton Laboratory

Date and Time: 
Monday, February 22, 2021 - 12:00pm to Tuesday, February 23, 2021 - 11:55am

AP483 Optics & Electronics Seminar presents "A Photonics Perspective on Data Center Interconnects"

Topic: 
A Photonics Perspective on Data Center Interconnects
Abstract / Description: 

The optical networks interconnecting datacenters (DCI) have grown the last decade more than any other transport network and have motivated the evolution of the original Internet architecture and of the global fiber infrastructure [1, 2, 3]. The current growth is also projected to continue strong by at least 2 more orders of magnitude [3, 4], placing DCI at the frontier of optical fiber communications. This presentation offers an industry perspective on DCI-motivated innovations and challenges in optical systems and photonics technology. Notably, photonic integration combined with coherent WDM and advancements in DSP and Moore's law, is enabling current DCI systems to operate ever closer to the fiber Shannon limit by exceeding 6 b/s/Hz spectral-efficiency in transatlantic deployments or reaching 25 Gb/s per Watt power-efficiency in metro DCI 400GE pluggable coherent WDM transceivers [1, 3].

1. L. Paraschis et al "Innovations in Inter Data Center Transport Networks", Chapter 15 (pp. 673 - 718) in Optical Fiber
Telecommunications VII, Edited by Alan E. Willner, Elsevier, ISBN 978-0128165027 (2019).
2. L. Paraschis, "Advancements in Metro Regional and Core Transport Network Architectures for the Next-Generation
Internet", Chapter 18 (pp. 793–817) in Optical Fiber Telecommunications VI Volume B, Systems and Networks, Edited by
Ivan Kaminow, Tingye Li, Alan E. Willner, Elsevier, ISBN 978-0123969606 (2016).
3. U. Holzle, "A Ubiquitous Cloud Requires a Transparent Network", IEEE/OSA Conference on Optical Fiber Communications
(OFC), Plenary (2017), and V. Vusirikala, "SDN Enabled Programmable, Dynamic Optical Layer", European Conference on
Communications (ECOC), Plenary (2017).
4. James Hamilton, "How Many Data Centers Needed World-Wide", https://perspectives.mvdirona.com/2017/04/how- manydata-centers-needed-world-wide (last accessed 2021/01/24).

Date and Time: 
Monday, February 8, 2021 - 12:00pm to Tuesday, February 9, 2021 - 11:55am

AP483 Optics & Electronics Seminar presents "Extreme optics with zero-index and flat-band metamaterials"

Topic: 
Extreme optics with zero-index and flat-band metamaterials
Abstract / Description: 

Nanotechnology has enabled the development of nanostructured composite materials (metamaterials) with exotic optical properties not found in nature. In the most extreme case, we can create materials which support light waves that propagate with infinite phase velocity, corresponding to a refractive index of zero. We have developed a variety of in-plane metamaterial designs that permit obtaining a refractive index of zero in the optical regime. We will report on some of the exotic physics of zero-index metamaterials, including strong enhancement of nonlinear optical phenomena, and on flat-bands generated by twisted bilayer photonic crystals.

Date and Time: 
Monday, February 1, 2021 - 4:15pm

OSA/SPIE present "Observing Ocean Health With A Global Network of Chemical and Biological Sensors on Robotic Platforms: Biogeochemical-Argo"

Topic: 
Observing Ocean Health With A Global Network of Chemical and Biological Sensors on Robotic Platforms: Biogeochemical-Argo
Abstract / Description: 

The ocean is under threat from a variety of processes driven by increasing atmospheric carbon dioxide such as ocean warming, changing winds and currents, decreasing pH and oxygen, and less ice cover at high latitudes. However, vast areas of the open ocean are sampled from research ships for chemical and biological properties only once per decade or less, with sampling occurring mainly in summer. Our ability to detect changes in ocean chemical and biological processes that may be occurring are greatly hindered by this undersampling. Robotic platforms carrying chemical and biological sensors that can monitor ocean metabolism, such as rates of oxygen production, nutrient uptake, accumulation of plankton biomass, and respiration, are required. The platforms and sensors must operate for the 5 to 10 year period between research vessel visits with no direct human intervention and little or no chance for sensor recalibration. Here, I'll describe the BGC-Argo network, which is being implemented to meet this mission. The BGC-Argo array is based on profiling floats that cycle through the upper 2 kilometers of the ocean every 10 days for 4 to 6 years. These floats carry optical sensors for oxygen, nitrate, chlorophyll, and particles, as well as electrochemical sensors for pH and physical sensors for temperature, pressure and salinity. The nitrate and pH sensors used in the array were developed at MBARI. With funding from NSF, NOAA, and NASA, we have deployed 200 floats in the Southern Ocean over the past 6 years. A recent research infrastructure grant from the NSF will extend the Southern Ocean array to the globe with 500 floats additional floats.

Date and Time: 
Tuesday, January 26, 2021 - 1:30pm

OSA/SPIE present "Silicon-based Optical Biosensors"

Topic: 
Silicon-based Optical Biosensors
Abstract / Description: 

Silicon-based optical biosensors hold great promise as low-cost, lab-on-chip sensor array elements due to their compatibility with both standard microelectronics processing and standard surface functionalization techniques. Key metrics of these optical biosensors include sensitivity, which is largely derived from the level of interaction between light and the target molecules to be detected, selectivity, and robustness. This talk will present several approaches to increase detection sensitivity through the use of on-chip resonant cavity geometries and porous substrates. The outlook for translating promising silicon-based benchtop sensing platforms into reliable clinical and point-of-care diagnostic devices will also be discussed.

Date and Time: 
Thursday, December 3, 2020 - 1:30pm
Venue: 
Zoom ID: 97038306925; +password

AP 483 Seminar presents "Organic small molecule integrated photonics"

Topic: 
Organic small molecule integrated photonics
Abstract / Description: 

The initial, landmark integrated photonic devices relied on silicon and III-V materials, and recent advances in material fabrication and deposition methods have enabled a plethora of new technologies based on materials with higher optical nonlinearities, including 2D materials and organic polymers. However, nonlinear optical (NLO) organic small molecules have not experienced similar growth due to a perceived environmental instability and to challenges related to intra and intermolecular interactions. Because NLO small molecules have NLO coefficients that are orders of magnitude larger than conventional optical materials, developing strategies to fabricate optical devices could enable significant performance improvements. In recent work, we combined conventional top-down fabrication methods with bottom-up techniques to develop on-chip devices that incorporated NLO optical small molecules. These hybrid systems provide access to optical behavior and performance not attainable with conventional material systems. In this seminar, I will discuss a couple examples of NLO small molecule integrated resonators, including Raman lasers and all optically-switchable devices.


This seminar is sponsored by the department of Applied Physics and the Ginzton Laboratory.

Date and Time: 
Monday, October 19, 2020 - 4:15pm

Pages

Subscribe to RSS - Optics and Electronics Seminar