Author(s): Hui Cao and Jan Wiersig
This is a review on theoretical and experimental studies on dielectric microcavities, which play a significant role in fundamental and applied research. The basic concepts and theories are introduced. Experimental techniques for fabrication of microcavities and optical characterization are described…
[Rev. Mod. Phys. 87, 61] Published Thu Jan 22, 2015
We study the fluctuations of the light emitted by two identical incoherent point sources in a disordered environment. The intensity-intensity correlation function and the speckle contrast, obtained after proper temporal and configurational averaging, encode the relative distance between the two sources. This suggests the intriguing possibility that intensity measurements at only one point in a speckle pattern produced by two incoherent sources can provide information about the relative distance between the sources, with a precision that is not limited by diffraction. The theory also suggests an alternative approach to Green function retrieval technique, where the correlations of the isotropic ambient noise detected by two receivers are replaced by a measurement at a single point of the noise due to two fluctuating incoherent sources.
Nature Photonics 9, 78 (2015). doi:10.1038/nphoton.2015.1
Authors: Kevin P. Homewood & Manon A. Lourenço
The development of a group IV semiconductor laser that is CMOS-compatible represents a step towards the creation of fully integrated electronic and photonic circuitry.
Author(s): Martin Neugebauer, Thomas Bauer, Andrea Aiello, and Peter Banzer
Under certain conditions the spin of photons can acquire an unusual transverse component. Using intensity differences in the far-field, the transverse spin density is experimentally measured.
[Phys. Rev. Lett. 114, 063901] Published Mon Feb 09, 2015
We are all well aware of how difficult is to get a permanent position in academia. The employers are very cautious as the tenured position comes with a very strong contractual stability and in some country with immortality (as civil service status). The postdocs work longer and longer hours to face the increasing competition. Academia needs more and more advanced skills that can only be acquired with years of experience but it refrains from rewarding it with a permanent job. An interesting alternative is that of the academic freelancer as proposed by Katie Rose Guest Pryal here, as a mean to alleviate the intense and extenuating life of a postdoc or not-tenured academic.
We have already started such an experiment, as I have hired a recently graduate and unemployed colleague to perform some theoretical calculations that we need for our experiments. The difference with respect to a normal collaboration is that this time I am paying him by the hour and he is performing the work choosing his time and without being based in London, just coming for a meetings to discuss the results. All the other discussions are done by Skype, email and probably soon in Slack.
In this way we can reward skills and actual hours of work, and potentially we can resolve personal issues such as family relocation etc… Would this work also for experimental work? It is hard to tell, but I could imagine having a setup in my house and performing experiments on demand as a freelancer does. Shared facilities similar to maker and hacker space could also make lab space and equipment more accessible.
Sooner or later we will have to invent a new way to develop science, a research 2.0, and it may start by embracing new concept such as remote and freelance work.
High resolution optical microscopy is essential in neuroscience but suffers from scattering in biological tissues. It therefore grants access to superficial layers only. Recently developed techniques use scattered photons for imaging by exploiting angular correlations in transmitted light and could potentially increase imaging depths. But those correlations (`angular memory effect') are of very short range and, in theory, only present behind and not inside scattering media. From measurements on neural tissues and complementary simulations, we find that strong forward scattering in biological tissues can enhance the memory effect range (and thus the possible field-of-view) by more than an order of magnitude compared to isotropic scattering for $\sim$1\,mm thick tissue layers.
Author(s): F. Antenucci, C. Conti, A. Crisanti, and L. Leuzzi
We present a unified approach to the theory of multimodal laser cavities including a variable amount of structural disorder. A general mean-field theory is studied for waves in media with variable nonlinearity and randomness. Phase diagrams are reported in terms of optical power, degree of disorder,…
[Phys. Rev. Lett. 114, 043901] Published Fri Jan 30, 2015
Author(s): J. Cuerda, F. Rüting, F. J. García-Vidal, and J. Bravo-Abad
In the context of plasmonic nanolasers, it has been previously recognized that systems with physically extended modes (as opposed to isolated cavity modes) can support lasing, and plasmonic crystals are a platform for such effects. In the present paper the authors present a general study that explores, from a unified perspective, the lasing properties of plasmonic crystals incorporating optically pumped four-level gain media.
[Phys. Rev. B 91, 041118(R)] Published Mon Jan 26, 2015
The Casimir force is a spectacular consequence of the existence of vacuum fluctuations and thus deserves a place in courses on quantum theory. We argue that the scattering approach within a one-dimensional field theory is well suited to a discussion of the Casimir effect. It avoids in a transparent way divergences appearing in the evaluation of the vacuum energy. Furthermore, the scattering approach connects in a natural manner to the standard discussion of one-dimensional scattering problems in a quantum theory course. Finally, it allows for the introduction to students of the methods employed in the current research literature to determine the Casimir force in real-world systems.
Author(s): Félix Ginot, Isaac Theurkauff, Demian Levis, Christophe Ybert, Lydéric Bocquet, Ludovic Berthier, and Cécile Cottin-Bizonne
Populations that translate energy into motion constitute active matter. New research shows that activity induces a nonequilibrium adhesion between colloidal microspheres, quantified by an activity-dependent equation of state.
[Phys. Rev. X 5, 011004] Published Fri Jan 23, 2015
Author(s): Matthieu Davy, Zhou Shi, Jing Wang, Xiaojun Cheng, and Azriel Z. Genack
We show in microwave measurements and computer simulations that the contribution of each eigenchannel of the transmission matrix to the density of states (DOS) is the derivative with angular frequency of a composite phase shift. The accuracy of the measurement of the DOS determined from transmission…
[Phys. Rev. Lett. 114, 033901] Published Fri Jan 23, 2015
Author(s): Vincenzo Grillo, Gian Carlo Gazzadi, Erfan Mafakheri, Stefano Frabboni, Ebrahim Karimi, and Robert W. Boyd
Researchers generated an electron beam with very high orbital angular momentum—potentially good for atomic-scale images of the magnetism in materials.
[Phys. Rev. Lett. 114, 034801] Published Fri Jan 23, 2015
Getting nice figures out of MATLAB can be a challenge. Sometimes it’s fine, but if you’ve hit upon a figure that simply isn’t exporting nicely (bad vector rendering, lost transparency, etc.), check out the export_fig project on Undocumented MATLAB.
Colorbrewer was designed for cartography, but is useful for figure color schemes and look up tables (LUTs). The web interface is slick, offers an immediate preview, and the look up table can be exported. Colorblind-safe and print-safe options can be designed.
Author(s): Timothy Amoah and Marian Florescu
Hyperuniform disordered materials are a class of photonic solids with a constrained randomness that have short-range order and long-range statistical isotropy. In these materials, calculations suggest a new type of high-Q localization mechanism in optical cavities, that has no analogue in periodic or quasi-periodic photonic crystals.
[Phys. Rev. B 91, 020201(R)] Published Tue Jan 20, 2015
Article
Replica symmetry breaking, in which identical systems subject to identical conditions evolve to different end states, has been predicted to occur in many contexts but has yet to be observed experimentally. Ghofraniha et al. report evidence for its occurrence in the pulse-to-pulse variations of a random laser.
Nature Communications doi: 10.1038/ncomms7058
Authors: N. Ghofraniha, I. Viola, F. Di Maria, G. Barbarella, G. Gigli, L. Leuzzi, C. Conti
Author(s): Louis Dellieu, Olivier Deparis, Jérôme Muller, and Michaël Sarrazin
Nanostructures are commonly used for developing superhydrophobic surfaces. However, available wetting theoretical models ignore the effect of vacuum photon-mode alteration on van der Waals forces and thus on hydrophobicity. Using first-principles calculations, we show that superhydrophibicity of nan…
[Phys. Rev. Lett. 114, 024501] Published Wed Jan 14, 2015
In this paper, we discuss what is, what is not, and what is only sort of superresolution microscopy. We begin by considering optical resolution, first in terms of diffraction theory, then in terms of linear-systems theory, and finally in terms of techniques that use prior information, nonlinearity, and other tricks to improve resolution. This discussion reveals two classes of superresolution microscopy, “pseudo” and “true.” The former improves images up to the diffraction limit, whereas the latter allows for substantial improvements beyond the diffraction limit. The two classes are distinguished by their scaling of resolution with photon counts. Understanding the limits to imaging resolution involves concepts that pertain to almost any measurement problem, implying a framework with applications beyond optics.
