Author(s): Jianji Yang, Mathias Perrin, and Philippe Lalanne
Hybrid nanostructures composed of both typical atoms and metallic nanoparticles such as nanoresonators host a variety of optical properties. Analytical modeling is used to derive the optical responses of such materials in a computationally feasible way.
[Phys. Rev. X 5, 021008] Published Fri Apr 17, 2015
Chapter 2 in the book "Light localisation and lasing Random and Pseudo-random Photonic Structures" eds by Mher Ghulinyan and Lorenzo Pavesi
Fundamental concepts in the quasi-one-dimensional geometry of disordered wires and random waveguides in which ideas of scaling and the transmission matrix were first introduced are reviewed. We discuss the use of the transmission matrix to describe the scaling, fluctuations, delay time, density of states, and control of waves propagating through and within disordered systems. Microwave measurements, random matrix theory calculations, and computer simulations are employed to study the statistics of transmission and focusing in single samples and the scaling of the probability distribution of transmission and transmittance in random ensembles. Finally, we explore the disposition of the energy density of transmission eigenchannels inside random media.
| Piled Higher & Deeper by Jorge Cham |
www.phdcomics.com
|
|
 |
||
|
title:
"Amount of Time Spent Writing your Thesis" - originally published
5/1/2015
For the latest news in PHD Comics, CLICK HERE! |
||
We demonstrate that due to strong modal interactions through cross-gain saturation, the onset of a new lasing mode can switch off an existing mode via a negative power slope. In this process of interaction-induced mode switching (IMS) the two involved modes maintain their identities, i.e. they do not change their spatial field patterns or lasing frequencies. For a fixed pump profile, a simple analytic criterion for the occurrence of IMS is given in terms of their self- and cross-interaction coefficients and non-interacting thresholds, which is verified for the example of a two-dimensional microdisk laser. When the spatial pump profile is varied as the pump power is increased, IMS can be induced even when it would not occur with a fixed pump profile, as we show for two coupled laser cavities. Our findings apply to steady-state lasing and are hence different from dynamical mode switching or hopping. IMS may have potential applications in robust and flexible all-optical switching.
Article
The work fluctuations of systems driven out of equilibrium are governed by the same large-deviation theory as wavefunction amplitudes close to the Anderson localization transition. Exploiting this analogy, the authors generalize the Jarzynski equality, verifying their relation on a single-electron box.
Nature Communications doi: 10.1038/ncomms8010
Authors: I.M. Khaymovich, J.V. Koski, O.-P. Saira, V.E. Kravtsov, J.P. Pekola
Article
The transparent wings of the glasswing butterfly have a low reflectance over the visible spectrum thanks to the nanopillars distributed across them. Siddique et al . show that this behaviour still works at high angles of incidence because of the random height distribution of the pillars.
Nature Communications doi: 10.1038/ncomms7909
Authors: Radwanul Hasan Siddique, Guillaume Gomard, Hendrik Hölscher
Author(s): Mark Kasperczyk, Steven Person, Duarte Ananias, Luis D. Carlos, and Lukas Novotny
We use the magnetic field distribution of an azimuthally polarized focused laser beam to excite a magnetic dipole transition in Eu3+ ions embedded in a Y2O3 nanoparticle. The absence of the electric field at the focus of an azimuthally polarized beam allows us to unambiguously demonstrate that the n…
[Phys. Rev. Lett. 114, 163903] Published Thu Apr 23, 2015
Zero-mode waveguides (ZMWs) are confining light into attoliter volumes, enabling single molecule fluorescence experiments at physiological micromolar concentrations. Among the fluorescence spectroscopy techniques that can be enhanced by ZMWs, F\"{o}rster resonance energy transfer (FRET) is one of the most widely used in life sciences. Combining zero-mode waveguides with FRET provides new opportunities to investigate biochemical structures or follow interaction dynamics at micromolar concentration with single molecule resolution. However, prior to any quantitative FRET analysis on biological samples, it is crucial to establish first the influence of the ZMW on the FRET process. Here, we quantify the FRET rates and efficiencies between individual donor-acceptor fluorophore pairs diffusing in aluminum zero-mode waveguides. Aluminum ZMWs are important structures thanks to their commercial availability and the large literature describing their use for single molecule fluorescence spectroscopy. We also compare the results between ZMWs milled in gold and aluminum, and find that while gold has a stronger influence on the decay rates, the lower losses of aluminum in the green spectral region provide larger fluorescence brightness enhancement factors. For both aluminum and gold ZMWs, we observe that the FRET rate scales linearly with the isolated donor decay rate and the local density of optical states (LDOS). Detailed information about FRET in ZMWs unlocks their application as new devices for enhanced single molecule FRET at physiological concentrations.
The great potential of Dirac electrons for plasmonics and photonics has been readily recognized after their discovery in graphene, followed by applications to smart optical devices. Dirac carriers are also found in topological insulators (TI) --quantum systems having an insulating gap in the bulk and intrinsic Dirac metallic states at the surface--. Here, we investigate the plasmonic response of ring structures patterned in Bi$_2$Se$_3$ TI films, which we investigate through terahertz (THz) spectroscopy. The rings are observed to exhibit a bonding and an antibonding plasmon modes, which we tune in frequency by varying their diameter. We develop an analytical theory based on the THz conductivity of unpatterned films, which accurately describes the strong plasmon-phonon hybridization and Fano interference experimentally observed as the bonding plasmon is swiped across the promineng 2\,THz phonon exhibited by this material. This work opens the road for the investigation of plasmons in topological insulators and for their application in tunable THz devices.
Multi-photon propagation in connected structures - a quantum walk - offers the potential for simulating complex physical systems and provides a route to universal quantum computation. Increasing the complexity of quantum photonic networks where the walk occurs is essential for many applications. Here, we implement a quantum walk of indistinguishable photon pairs in a multimode fiber supporting 380 modes. Using wavefront shaping, we control the propagation of the two-photon state through the fiber in which all modes are coupled. Excitation of arbitrary output modes of the system is realized by controlling classical and quantum interferences. This experiment demonstrates a highly multimode platform for multi-photon interference experiments and provides a powerful method to program a general high-dimensional multiport optical circuit. This work paves the way for the next generation of photonic devices for quantum simulation, computing and communication.
In early 2014, Vancouver-based graphic artist Joey Camacho set out to learn more about rendering images using Cinema 4D and Octane Render, with the goal of creating a new piece each day. His first attempts were pretty rudimentary, but it wasn’t long before his exploration and experimentation began to pay off with increasinly subtle details inspired by biology, sound, and geometry. Only several months into his ‘Progress Before Perfection‘ project, he started getting requests for prints as his images were shared widely around Tumblr and elsewhere. You can see more of his work on Behance and prints of many pieces are available through his website.
In early 2014, Vancouver-based graphic artist Joey Camacho set out to learn more about rendering images using Cinema 4D and Octane Render, with the goal of creating a new piece each day. His first attempts were pretty rudimentary, but it wasn’t long before his exploration and experimentation began to pay off with increasinly subtle details inspired by biology, sound, and geometry. Only several months into his ‘Progress Before Perfection‘ project, he started getting requests for prints as his images were shared widely around Tumblr and elsewhere. You can see more of his work on Behance and prints of many pieces are available through his website.
Author(s): Jianji Yang, Mathias Perrin, and Philippe Lalanne
Hybrid nanostructures composed of both typical atoms and metallic nanoparticles such as nanoresonators host a variety of optical properties. Analytical modeling is used to derive the optical responses of such materials in a computationally feasible way.
[Phys. Rev. X 5, 021008] Published Fri Apr 17, 2015
The future of the postdoc
Nature 520, 7546 (2015). http://www.nature.com/doifinder/10.1038/520144a
Author: Kendall Powell
There is a growing number of postdocs and few places in academia for them to go. But change could be on the way.
All that glitters
Nature 520, 7546 (2015). doi:10.1038/520131a
A review of the United Kingdom’s progress towards ‘gold’ open-access research is instructive — for funders, publishers and scientists both at home and abroad.
Author(s): T. Iffländer, S. Rolf-Pissarczyk, L. Winking, R. G. Ulbrich, A. Al-Zubi, S. Blügel, and M. Wenderoth
The electronic charge distribution at the iron/gallium interface is imaged directly with high spatial and energetic resolution. The metal-semiconductor electronic barrier properties are found to be dependent on both the charge distribution and chemical bonds between the metal and semiconductor atoms.
[Phys. Rev. Lett. 114, 146804] Published Thu Apr 09, 2015
In the talk I gave at the Short Course at SfN 2014, I briefly discussed the process of optical system design. A common strategy is to start with a published design, or at least a general scheme (series of lens types), and then make modifications to fit the target application. Finding these published designs can be tedious. The patent literature and journal publications rarely come with downloadable files, and so the parameters have to be manually entered. Major design houses will have databases of designs in digital form, but not all of us work in such an environment. Dan Reiley’s Lens-designs.com has a bunch of Zemax and OSLO files available under the MIT license. Camera lenses, microscope objectives, and more…
A trio of researchers at Stanford recently published an article in Nature that explains the curious attraction found in droplets of everyday food coloring. The paper is the culmination of hundreds of experiments that began in 2009 when Nate Circa was working on an unrelated experiment as an undergraduate at the University of Wisconsin. Circa noticed that when drops of food coloring were placed on a slide they exhibited bizarre behaviors: identical colors would find matches while different colors would seemingly hunt each other.
Circa soon teamed up with Manu Prakash and Adrien Benusiglio who began working on a series of increasingly refined studies to understand why these single droplets appeared to mimic biological processes, resulting in behaviors that looked like chasing, dancing, or avoidance. One of the keys was the interaction of two different compounds found in food coloring: water and propylene glycol. Tom Abate writing for Stanford explains:
The critical fact was that food coloring is a two-component fluid. In such fluids, two different chemical compounds coexist while retaining separate molecular identities. The droplets in this experiment consisted of two molecular compounds found naturally in food coloring: water and propylene glycol. The researchers discovered how the dynamic interactions of these two molecular components enabled inanimate droplets to mimic some of the behaviors of living cells.
This complex behavior is something called artificial chemotaxis which Manu Prakash explains in layman’s terms in the video above:
The physical properties of these fluids give rise to this immense complexity of behavior. For example, chasing and sensing each other, and very much what we call artificial chemotaxis. Chemotaxis is the idea in biology that one single cell can sense where its enemy is, and it brings up all its machinery, and it chases that enemy to try to eat it.
If you really want to get into the nitty gritty of fluid dynamics and molecular physics you can read the full paper in Nature and a bit of a summary on Stanford News. (via, appropriately, F*ck Yeah Fluid Dynamics)
