Optics and Electronics Seminar

SCIEN Colloquium and EE 292E present "Snapshot multispectral imaging from a different angle"

Topic: 
Snapshot multispectral imaging from a different angle
Abstract / Description: 

Combining photography and spectroscopy, spectral imaging enables us to see what no traditional color camera has seen before. The current trend is to miniaturize the technology and bring it towards industry. In this talk, I will first give a general introduction to the most common pitfalls of spectral imaging and the challenges that come with miniaturization. Major pitfalls include balancing cross-talk, quantum efficiency, illumination and the optics. Miniaturization has become possible thanks to the monolithic per-pixel integration of thin-film Fabry-Pérot filters on CMOS imaging sensors. I will explain the difficulty of using these cameras with non- telecentric lenses. This is a major concern because of the angular dependency of the thin-film filters. I will demonstrate how this important issue can be solved using a model-based approach.

Date and Time: 
Wednesday, June 12, 2019 - 4:30pm
Venue: 
Packard 101

OSA/SPIE, SPRC and Ginzton Lab present "Effective medium approach towards topological photonics"

Topic: 
Pandora and Prometheus: Science, Scientists, and Society
Abstract / Description: 

As researchers in photonics we have both opportunities to positively impact people's lives and responsibilities to assist in ethical integration of these important new and disruptive technologies into modern society. While photonics provides solutions to critical global issues, such as key technology for measuring the environment and mitigating the impact of climate change, we are also developing new capabilities, which test society's legal and moral frameworks. Photonics enables the internet and social networking, high throughput sequencing of the human genome, pre-implantation testing of human embryos, measurement and control of neural networks in vivo—advances which present significant ethical challenges.

In addition, as scientists we are part of a global research community with the common goal of openly sharing our knowledge world-wide. Knowledge gives competitive and strategic advantages to those having access to it, leading to government pressure to limit free access to and unrestricted dissemination of scientific research. How do we reconcile our national responsibilities and loyalties with our responsibilities as members of the global scientific community to openly share our knowledge? These pressures become particularly acute when most of our research funding comes from federal/national sources.

Both students and faculty are welcome and encouraged to participate in an open discussion of these topics over lunch.

Date and Time: 
Thursday, June 6, 2019 - 12:00pm
Venue: 
Spilker 232

OSA/SPIE, SPRC and Ginzton Lab present "Ultrafast Multidimensional Coherent Spectroscopy of Color Centers in Diamond"

Topic: 
Ultrafast Multidimensional Coherent Spectroscopy of Color Centers in Diamond
Abstract / Description: 

Color centers in diamond are point defects within the diamond host lattice that absorb and emit light at optical frequencies. Besides contributing to the striking visual characteristics of "fancy colored diamond" gemstones, the centers—particularly the negatively charged nitrogen-vacancy (NV) center and silicon-vacancy (SiV-) center—offer a number of possibilities for quantum computation and quantum information processing. In this talk, I will summarize recent work investigating the properties of negatively charged silicon-vacancy centers in diamond using the optical multidimensional coherent spectroscopy (MDCS). Finding suggest a strong influence of strain in determining the presence or absence of radiative coupling in the centers. By extension, the results reveal a new knob for tuning color-center-based photonic devices.

Date and Time: 
Thursday, May 30, 2019 - 4:15pm
Venue: 
Spilker 232

OSA/SPIE, SPRC and Ginzton Lab present "Recent Advances in Submarine Fiber Optical Systems"

Topic: 
Recent Advances in Submarine Fiber Optical Systems
Abstract / Description: 

Undersea fiber optical systems have shown tremendous advances over the past one or two decades. Capacities have increased by 20x while the cost per bit of submarine transmission has decreased by 250 times. These advances have been primarily a result of coherent transmission and I will highlight all of the main points regarding these advances. This has led to the recent deployment of 16-QAM transmission on a trans-Atlantic link! Future directions in submarine fiber optic transmission systems, such as SDM, will also be discussed.

Date and Time: 
Thursday, May 23, 2019 - 4:15pm
Venue: 
Spilker 232

OSA/SPIE, SPRC and Ginzton Lab present "Hot Topics in Optics and Photonics"

Topic: 
Hot Topics in Optics and Photonics
Abstract / Description: 

Optics and photonics is a diverse field, spanning dynamic commercial successes to slowly-moving niche markets to speculative research and fundamental science. But most people only work in small spaces of the field at a given time, whether they are working in industry or academia. It can be difficult to visualize the entire field and understand it. How do you forecast where the technology is going? What is the Next Big Thing? How do you know what is a hot topic and what is a buzzword? This talk will provide ways of looking at current hot topics in photonics, in both the research funding and commercial markets. It will also give some perspectives on selected topics and where they are going. The talk will give "market perspectives," which is to say that it's about the overall environment and near- to mid-term future, rather than recent scientific results.

Date and Time: 
Thursday, May 16, 2019 - 4:15pm
Venue: 
Spilker 232

OSA/SPIE present "Measuring Everything You've Always Wanted to Know About a Light Pulse"

Topic: 
Measuring Everything You've Always Wanted to Know About a Light Pulse
Abstract / Description: 

The vast majority of the greatest scientific discoveries of all time have resulted directly from more powerful techniques for measuring light. Indeed, our most important source of information about our universe is light, and our ability to extract information from it is limited only by our ability to measure it.


Interestingly, most of the light in our universe remains immeasurable, involving long pulses of relatively broadband light, necessarily involving ultrafast and extremely complex temporal variations in their intensity and phase. As a result, it is important to develop techniques for measuring, ever more completely, light with ever more complex submicron detail in space and ever more complex ultrafast variations in time. The problem is severely complicated by the fact that the timescales involved correspond to the shortest events ever created, and measuring an event in time seems to require a shorter one, which, by definition, doesn't exist!
Nevertheless, we have developed simple, elegant techniques for completely measuring such light, using the light to measure itself and yielding a light pulse's intensity and phase vs. time and space. One technique involves making an optical spectrogram of the pulse using a nonlinear optical medium and whose mathematics is equivalent to the two-dimensional phase-retrieval problem—a problem that's solvable only because the Fundamental Theorem of Algebra fails for polynomials of two variables. In addition, we have recently developed simple methods for measuring the complete spatio-temporal electric field [E(x,y,z,t)] of an arbitrary, potentially complex light pulse without the need to average over multiple pulses.

Date and Time: 
Friday, May 10, 2019 - 4:15pm
Venue: 
Packard 101

OSA/SPIE, SPRC and Ginzton Lab present "Effective medium approach towards topological photonics"

Topic: 
Effective medium approach towards topological photonics
Abstract / Description: 

Metamaterials have attracted tremendous attention due to their exotic optical properties and functionalities that are not attainable from naturally occurring materials. In particular, metamaterials can be designed to introduce strong spin-orbit coupling for light and consequently nontrivial topological properties. In this talk, I will start with a brief introduction to the concepts of Berry curvature, Chern number and topological photonics. I will show that combination of chirality and hyperbolicity – an extreme form of anisotropy, can result in nontrivial topological orders in metamaterials and consequently topologically protected photonic surface states that are immune from scattering by defects and sharp edges. The Weyl points in such systems result from the crossing between the bulk longitudinal plasmon mode and the transverse circularly polarized propagating modes. The photonic 'Fermi arcs' were directly observed in the microwave regime, which showed Riemann-surface like helicoid configuration in the energy-momentum space. I will further show that by designing the Weyl metamaterials with inhomogeneous unit cells, artificial magnetic field can be introduced which leads to the first observation of chiral zero Landau mode in photonic systems.

Date and Time: 
Monday, May 6, 2019 - 4:30pm
Venue: 
Y2E2 299

AP483 & AMO Seminar welcomes Tomas Cizmar, "Harnessing Multimode Propagation for Deep-tissue Imaging"

Topic: 
Harnessing Multimode Propagation for Deep-tissue Imaging
Abstract / Description: 

The turbid nature of refractive index distribution within living tissues introduces severe aberrations to light propagation thereby severely compromising image reconstruction using currently available non-invasive techniques. Numerous approaches of endoscopy, based mainly on fibre bundles or GRIN-lenses, allow imaging within extended depths of turbid tissues, however their footprint causes profound mechanical damage to all overlying regions and their imaging performance is limited.

Progress in the domain of complex photonics enabled a new generation of minimally invasive, high-resolution endoscopes by substitution of the Fourier-based image relays with a holographic control of light propagating through apparently randomizing multimode optical waveguides. This form of endo-microscopy became recently a very attractive way to provide minimally invasive insight into hard-to-access locations within living objects.

Professor Čižmár will review our fundamental and technological progression in this domain and introduce several applications of this concept in bio-medically relevant environments.


 

 

AP 483 & AMO Seminar Series
Time:
4:15 pm, every Monday (Refreshments begin at 4 pm)

Location:
Spilker Building Room 232

Date and Time: 
Monday, May 20, 2019 - 4:15pm
Venue: 
Spilker 232

AP483 & AMO Seminar presents "Computational Microscopy in Multiple-Scattering Samples"

Topic: 
Computational Microscopy in Multiple-Scattering Samples
Abstract / Description: 

Computational imaging involves the joint design of imaging system hardware and software, optimizing across the entire pipeline from acquisition to reconstruction. Computers can replace bulky and expensive optics by solving computational inverse problems. This talk will describe new microscopes that use computational imaging to enable 3D fluorescence and phase imaging in samples that incur multiple scattering. Our reconstruction algorithms are based on large-scale nonlinear non-convex optimization. Applications span optical bioimaging, X-ray and electron microscopy.


 

AP 483 & AMO Seminar Series

Time:
4:15 pm, every Monday (Refreshments begin at 4 pm)

Location:
Spilker Building Room 232

Date and Time: 
Monday, May 13, 2019 - 4:15pm
Venue: 
Spilker 232

#StanfordToo: A Conversation about Sexual Harassment in Our Academic Spaces

Topic: 
#StanfordToo: A Conversation about Sexual Harassment in Our Academic Spaces
Abstract / Description: 

Individuals of all genders invited to be a part of:
#StanfordToo: A Conversation about Sexual Harassment in Our Academic Spaces, where we will feature real stories of harassment at Stanford academic STEM in a conversation with Provost Drell, Dean Minor (SoM), and Dean Graham (SE3). We will have plenty of time for audience discussion on how we can take concrete action to dismantle this culture and actively work towards a more inclusive Stanford for everyone. While our emphasis is on STEM fields, we welcome and encourage participation from students, postdocs, staff, and faculty of all academic disciplines and backgrounds.

Date and Time: 
Friday, April 19, 2019 - 3:30pm
Venue: 
STLC 111

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