May 21, 2015
CLEO 2015 is the world’s premier laser and photonics conference and was held in San Jose from May 10th to 15th. It was a very high quality conference and exposition where 4,400 attendees came together, 226 exhibitors presented their technology and 1,380 presentations were held by scientists from around the world. Sessions were held in several areas of optics and photonics and focused on both fundamental science as well as on practical innovations, covering altogether a very broad range of topics such as high-resolution microscopy, plasmonics, metamaterials, attoscience, biosensing or quantum entanglement.
This year was particularly exciting for CLEO because six Nobel prizes went to opticians in 2014 (three in Physics and three in Chemistry), five of which attended the conference and gave talks in plenary sessions. Steven Chu, from Stanford University, who was awarded the 1997 Nobel Prize in Physics for the development of methods to cool and trap atoms with lasers also gave a talk in a plenary session entitled “Microscopy 2.0”, where he exposed his new research on high-resolution microscopy. Altogether, six Nobel laureates were present, which is an exceptional turn-out!
The 2014 Nobel Prize in Physics was awarded for the invention of efficient blue light-emitting diodes (LED’s) which has enabled bright and energy-saving white light sources. This invention has certainly changed the world and is going to continue doing because the energy footprint of lighting is going to reduce as countries progressively transit from traditional light bulbs to LED’s. Hiroshi Amano and Shuji Nakamura both emphasized the huge impact that LED’s will have in the world during their presentations. They also gave a comprehensive description of their carriers as scientists. As the audience listened, it became clear to everyone that they were isolated in their research in the 1980’s because they were the only scientists that were trying to use Gallium Nitride (GaN) to fabricate blue LED’s, which were deemed to be too difficult to produce. The vast majority of researchers were working on Zinc Selenide (ZnSe) at the time. But as Pr. Nakamura very humorously put it: “Today, everybody works on GaN”!
The 2014 Nobel Prize in Chemistry was awarded to Stefan Hell, William Moerner and Eric Betzig for the development of super-resolved fluorescence microscopy. S. Hell made a very pedagogical presentation of the technique he invented based on stimulated emission depletion (STED) Microscopy, while W. Moerner and E. Betzig described their personal experiences in using single-molecules to achieve super-resolution and gave a historical overview of the techniques involved. All presentations involved very impressive super-resolved images of biological systems such as cells or bacteria. E. Betzig insisted on the fact that rival techniques that achieve lower resolutions than his own also deserve a spotlight as they may be the ones that turn out to become viable applications in the end, because they involve lower intensities and smaller integration times. Both these features are important for live cell imaging for instance.
During the sessions that I attended, I realized that research at the Center for Metamaterials and Integrated Plasmonics (CMIP) was not only well represented by talks in several sessions, but also had a strong impact on current research as several groups cited work carried out at the Center in their presentations. I had the opportunity of attending several sessions. I realized that several topics are on the rise in optics. Parity-Time (PT) symmetry is definitely one of them. A lot of the theory and experiments involving PT-symmetric systems involve symmetric index guiding and an anti-symmetric gain-loss profile. As a matter of fact Xiang Zhang from the University of California Berkeley gave a tutorial on Recent Progress in Optical Metamaterials and made a clear focus on non-Hermitian optics and PT-symmetry. Another important and hot topic is Topological Photonics. The idea is to carefully design wavevector-space topologies to create interfaces that support states of light that are insensitive to impurities. This new science holds a lot of promise as it suggests the possibility of building photonic crystals, coupled resonators and metamaterials that are very weakly impacted by disorder, while maintaining the enhancement of light-matter interaction enabled by these structures.
I had the opportunity of giving two presentations for CMIP in the Nonlinear Plasmonics session. My first talk was entitled Large and Ultrafast Nonlinear Absorption of an Air/Gold Plasmonic Waveguide, in which I presented our recent work on the theoretical and experimental investigation of the nonlinear propagation of surface plasmons on an air/gold interface . Our experiments revealed large and ultrafast (100 fs) self-induced absorption and enabled direct measurement of the third-order nonlinear susceptibility. As metal nonlinearities have typically been neglected in past proposals of plasmonic based nonlinear devices, we think that our results will have important implications in the study and design of plasmonic systems and metamaterials, as the strong self-action will compete with other desirable nonlinear optical phenomena such as third-harmonic generation (THG) or four-wave mixing (FWM). However, it also provides a mechanism to achieve ultrafast plasmonic modulation. This work was a collaboration between David Smith’s group and Center faculty Maiken Mikkelsen.
The second talk I gave was on the Scaling of the Nonlinear Response of Metal/Dielectric Plasmonic Waveguides, where I presented our study of the nonlinear response of a single-interface plasmonic waveguide, where both the metal and the dielectric display nonlinearity . In this work, we introduced a figure-of-merit that guides metal/dielectric nanophotonic device design for specific applications. This work was a collaboration between David Smith’s group, and Center faculty Stéphane Larouche and Daniel Gauthier.
Among other notable presentations for CMIP was the talk given by Patrick Bowen on the Analytic Modeling of Metamaterial Absorbers, which generated a lot of interest within the session on Novel Optics . Gleb Akselrod also gave a remarkable presentation on Plasmonic Nanopatch Antennas for Large Purcell Enhancement in the Quantum Emission and Plasmonics session.
Over all, I feel like this year’s edition of CLEO was a remarkable event in many respects and one of the better conferences I have had the chance of attending. It is certainly exceptional to see six Nobel Prizes in one conference. I will gladly return to CLEO in the future.
 A. Baron, T. B. Hoang, C. Fang, M. H. Mikkelsen, and D. R. Smith, Large and Ultrafast Nonlinear Absorption of an Air/Gold Plasmonic Waveguide, CLEO: 2015 OSA Technical Digest (online) paper FM3E.4
 A. Baron, S. Larouche, D. J. Gauthier, and D. R. Smith, Scaling of the Nonlinear Response of Metal/Dielectric Plasmonic Waveguides, CLEO: 2015 OSA Technical Digest (online) paper FM3E.7
 P. Bowen, A. Baron, and D. R. Smith, Analytic Modeling of Metamaterial Absorbers, CLEO: 2015 OSA Technical Digest (online) paper FW4C.5
 G. M. Akselrod, C. Argyropoulos, T. B. Hoang, C. Ciraci, C. Fang, J. Huang, D. R. Smith, Plasmonic Nanopatch Antennas for Large Purcell Enhancement, CLEO: 2015 OSA Technical Digest (online) paper FW1E.2