Bulletin of the American Physical Society
2007 APS March Meeting
Volume 52, Number 1
Monday–Friday, March 5–9, 2007; Denver, Colorado
Session H44: Focus Session: Optical Properties of Nanocavities and Structured Materials |
Hide Abstracts |
Sponsoring Units: DMP Chair: Glenn Solomon, National Institute of Standards and Technology Room: Colorado Convention Center 507 |
Tuesday, March 6, 2007 8:00AM - 8:36AM |
H44.00001: Directed Self-Assembly of Single Quantum Dot Optical Devices Invited Speaker: Techniques that allow one to control the nucleation site of individual, self-assembled quantum dots are necessary for the fabrication of optical and electronic devices that must align subsequent control structures to the dots. In this talk I will describe a ``nanotemplate deposition'' technique that allows one to direct the surface migration of deposited Indium species during crystal growth so that InAs quantum dot nucleation sites can be controlled \textit{a-priori} with nanometre precision. Using this technique one can construct high finesse, two-dimensional photonic crystal microcavity membranes in which the optical defect mode is aligned both spectrally and spatially to a single InAs/InP, site-selected quantum dot emitting at 1550nm. I will describe the fabrication and optical characterisation of such cavities, with Purcell factors in excess of 4,000 and mode volumes of approximately $0.5\left( {\lambda /n} \right)^3$, and I will illustrate how coupling to these cavities using a tapered nanowire micro-loop fiber can be used to optimize the extraction efficiency for single photon source applications. [Preview Abstract] |
Tuesday, March 6, 2007 8:36AM - 8:48AM |
H44.00002: Photoluminescence up-conversion of single quantum dots in a microcavity. E. B. Flagg, A. Muller, X. Y. Wang, D. G. Deppe, W. Ma, J. Zhang, G. J. Salamo, M. Xiao, C. K. Shih We have studied photoluminescence upconversion in single self-assembled InGaAs quantum dots that are embedded in a planar optical microcavity. Upconversion is generally thermal and can be characterized unambiguously due to the absence of inhomogeneous broadening. A side-excitation photoluminescence technique allows us to detect arbitrarily close to the laser line thereby distinguishing otherwise unresolvable energy splittings. This allows the investigation of upconversion as a function of both temperature and energy separation. [Preview Abstract] |
Tuesday, March 6, 2007 8:48AM - 9:00AM |
H44.00003: Low-threshold few-emitter quantum dot lasing. Glenn Solomon, Wei Fang, Stephan Goetzinger, Zhigang Xie Ultra-low threshold lasing via a single emitter is of strong fundamental interest in solid-state and atomic physics. While lasing from a single emitter has not yet been observed in solid-state systems, a quantum dot (QD) gain medium of only a few QD states can be coupled to an optical cavity mode and lase. We describe such an ultra-low threshold lasing system here utilizing a microdisk cavity and a dilute QD gain medium. The microdisk is GaAs and supports high quality-factor whispering gallery modes. The QD gain medium is composed of InAs-based QDs formed epitaxially through lattice mismatch strain. Our systems show lasing even in the smallest, sub-2 micrometer disk diameters. Because of the high cavity quality factor, we observe nondegenerate modes due to broken symmetry. A typical QD spectrum of discrete emission lines observed at lower pump power is often highly modified near transparency leading to pump power dependent absorption. Changes in the cavity linewidth, second-order correlation measurements, and output emission versus input pumping are used to verify lasing. The system has sub-microwatt CW lasing thresholds and exhibits lasing from a small number of emitters. [Preview Abstract] |
Tuesday, March 6, 2007 9:00AM - 9:12AM |
H44.00004: Resonance photoluminescence from a single semiconductor quantum dot in a microcavity. A. Muller, E.B. Flagg, X.Y. Wang, D.G. Deppe, W. Ma, J. Zhang, G.J. Salamo, M. Xiao, C.K. Shih The analogue of resonance fluorescence in atomic physics is demonstrated for the first time in a zero-dimensional solid-state system consisting of self-assembled InGaAs quantum dots. The dots were embedded in a planar microcavity so that the quantum dot emission, coupled to the resonant cavity modes, was effectively decoupled from the excitation field. The latter was introduced via waveguide modes with a fiber in a side-excitation configuration. The result is a background-free detection of a single quantum dot's photoluminescence which shows antibunched photon emission and can be driven into Rabi oscillations using pulsed excitation. [Preview Abstract] |
Tuesday, March 6, 2007 9:12AM - 9:24AM |
H44.00005: Optical microtube ring resonators formed by rolled-up strained semiconductor bilayers Tobias Kipp, Christian Strelow, Holger Welsch, Christian Heyn, Detlef Heitmann Starting from an epitaxially grown InGaAs/GaAs bilayer and using optical lithography and wet-etching processes, we utilize the self-rolling mechanism of strained bilayers to fabricate self-supporting microtubes with diameters of about 5 $\mu m$ and wall thicknesses of only 100 -– 200 nm. We demonstrate these structure to act as optical ring resonators by measuring the photoluminescence of an optically active material, either quantum wells or self-assembled quantum dots, which is embedded into the tubes' walls. We find spectra of sharp modes arising from constructive interference of light running circularly around the micotube's axis inside its wall. The mode structure is in very good agreement with the result of a theoretical modeling of the microtube as a thin dielectric waveguide forming a closed ring. These novel microtube ring resonators, in which the optically active material is intrinsically located close to the optical field maximum, are good candidates for both, new optoelectronic devices and cavity quantum electrodynamic experiments. We gratefully acknowledge financial support of the Deutsche Forschungsgemeinschaft via the SFB 508 ``Quantum Materials'' and the Graduiertenkolleg 1286 ``Functional Metal-Semiconductor Hybrid Systems.'' [Preview Abstract] |
Tuesday, March 6, 2007 9:24AM - 9:36AM |
H44.00006: Voltage-controlled Deformation of Photonic Crystal Membranes Hubert J. Krenner, H. Kim, S. M. Thon, D. Bouwmeester, N. G. Stoltz, P. M. Petroff We present a novel photonic device consisting of a free-standing Photonic Crystal (PC) membrane which can be mechanically deformed by an external voltage. This is realized by introducing doped layers in the membrane and the underlying substrate. We embed self-assembled InAs quantum dots (QDs) in the membrane as active emitters. In a first step metal contacts are fabricated for both doped layers of the device. Two-dimensional PC microcavities are defined by electron beam lithography and ICP etching. The PC membrane is finalized by selectively removing an AlGaAs layer underneath the patterned region. By applying a bias voltage between the two contacts we are able to change the electrostatic force between the substrate and the membrane analogous to a plate capacitor. Due to the small thickness of the membrane the electrostatic force leads to a deformation with vertical displacements up to 250nm at room temperature. We demonstrate that at low temperatures this displacement can be reversibly changed over a wide range by an external voltage leading to a visible deformation of the membrane. We present first results of micro-PL experiments to probe the influence of the deformation on the optical modes of PC microcavities. - Supported by the Alexander-von-Humboldt Foundation [Preview Abstract] |
Tuesday, March 6, 2007 9:36AM - 9:48AM |
H44.00007: Controlling the Optical Properties of Self-Assembled Quantum Dots Using External Strain M. Zielinski, W. Jaskolski, G. W. Bryant, J. Diaz, J. Aizpurua Passive control of the optics of self-assembled quantum dots is achieved by controlling dot size, shape and composition via growth. Local strain from lattice mismatch between the dot and barrier influences the electronic properties. Dynamical control could be achieved via imposed external strain to change level degeneracies, polarize transitions, or modify coupling between dots. Moreover dots could be coupled to bending modes to optically cool nanomechanical oscillators to the quantum limit. To understand the impact of externally imposed strain on the electronic states of self-assembled dots, we use a tight- binding theory of dots that incorporates local strain from lattice mismatch and externally imposed strain from applied stressors or the bend in a nanomechanical oscillator. Energy level shifts depend on the position of the dot in a nanomechanical oscillator and how the oscillator is bent. Energy levels can red-shift and blue-shift depending on how the external strain is imposed. Shifts in the electronic levels due to different bending modes are determined. This allows us to assess how much active control is possible. [Preview Abstract] |
Tuesday, March 6, 2007 9:48AM - 10:00AM |
H44.00008: Strong Second Order Piezoelectric Effect in InGaAs/GaAs Nanostructures Gabriel Bester, Alex Zunger, Xifan Wu, David Vanderbilt We show that the piezoelectric effect that describes the emergence of an electric field in response to a crystal deformation has strong contributions in III-V semiconductors such as GaAs and InAs from second-order effects that have been neglected so far. We calculate the first and second-order piezoelectric tensors using density functional theory. Applying these calculated tensors to quantum wells [1] gives piezoelectric fields that agree well with experiments, whereas neglect of non-linearities leads to qualitative disagreements. We find that the linear and the quadratic piezoelectric coefficients have the opposite effect on the field. Which term dominates is stronlgy dependend on concentration $x$ for quantum wells and for large $x$ the quadratic terms strongly dominates. Applying our theory to quantum dots [2] shows that both term nearly cancel each other so neglecting piezoelectricity is a better approximation than using only the linear term. Thus, the piezoelectric field turns out to be a rare example of a physical quantity for which the first-order and second-order contributions are of comparable magnitude.\\[.1cm] [1] G. Bester, A. Zunger, X. Wu and D. Vanderbilt, Phys. Rev. B. {\bf 74}, 081305({\bf R}) (2006). [2] G. Bester, X. Wu, D. Vanderbilt and A. Zunger, Phys. Rev. Lett. {\bf 96}, 187602 (2006).\\[.1cm] [Preview Abstract] |
Tuesday, March 6, 2007 10:00AM - 10:12AM |
H44.00009: Single molecule fluorescence decay rate statistics in clusters of nanoparticles Luis Froufe, Juan Jose Saenz, Remi Carminati In this work, we study the fluorescence rate statistics of a single emitter in a finite size (nanoscopic) random medium (cluster), made of small spherical particles. For a given configuration of the system, we calculate numerically the Green tensor of the system. We deduce the spontaneous decay rate $\Gamma$, as well the radiative and the nonradiative contributions. Repeating the calculation for the configuration distribution allows to compute the full statistics. These numerical experiments are used as a basis for a physical discussion. We focus on the regime in which the statistics is determined by near field interactions, with negligible multiple scattering. The decay rate statistics is influenced by the local environment of the emitter. In particular, we show that for moderate absorption, the nonradiative contribution is proportional to the imaginary part of the dielectric function of the particles, while the radiative contribution is almost constant. An important result is that the standard deviation exhibits diferent regimes dominated by either near-field scattering or absorption. This quantity could be used for nanoscale imaging in complex media. [Preview Abstract] |
Tuesday, March 6, 2007 10:12AM - 10:24AM |
H44.00010: Diffusion limit in complex media Lev Deych, Mikhail Eremetnchouk, Hui Cao, Heeso Noh, Alexander Lisyansky Structures with pre-engineered spatial modulations of the dielectric function attract a lot of attention because they provide possibility to control effectively propagation of light. Recently it has been realized that unusual optical characteristics of such structures have a deep impact on their general physical properties. Even such well-studied phenomenon as light transport in disordered media is strongly affected by the regular modulation of the dielectric function. As a result, the transport in complex media has specific features, which can not be understood in the framework of the standard theory. We present the general theory of the diffusive (completely incoherent) limit in disordered structures with regular modulation of the dielectric function. We establish a relation between this limit and equilibrium understood from the statistical physics point of view. We show, in particular, that in the case of weak disorder the diffusion limit is virtually independent on the disorder and is nontrivially determined by properties of the ideal structure. We demonstrate how the diffusion of light appears as the perturbation of equilibrium. [Preview Abstract] |
Tuesday, March 6, 2007 10:24AM - 10:36AM |
H44.00011: Aperiodic nanostructured optical devices fabricated with a femtosecond laser Timothy Gerke, Jeremy Brown, Wenjian Cai, Ariel Libertun, Rafael Piestun Periodic three-dimensional (3D) structures have increasingly caught the attention of the scientific community. Aperiodic 3D structures, however, have remained relatively unexplored. We present structural and optical characterization of 3D aperiodic nanostructures created by scanning focused femtosecond (fs) laser pulses to produce permanent refractive index changes inside glass. We created polarization-sensitive devices using the effect of fs-laser-induced birefringence in fused silica. In this regime, the laser-created plasma gives origin to subwavelength structures that generate anisotropy by the effect of form birefringence. We demonstrated polarization-selective computer-generated holograms using this effect in three dimensions. These holograms form different reconstructions for different illuminating polarization states [Preview Abstract] |
Tuesday, March 6, 2007 10:36AM - 10:48AM |
H44.00012: ABSTRACT WITHDRAWN |
Tuesday, March 6, 2007 10:48AM - 11:00AM |
H44.00013: Azobenzene-based photomechanical monolayers as light-addressable nano-engineered structures. J.M. Dahdah, T.E. Furtak, D.M. Walba, G. Fang, Y. Yi, J.E. Maclennan, N.A. Clark Azobenzene-based photomechanical monolayers have received a great deal of attention for their potential as platforms for light-addressable nano-engineered structures in bioscience, photonics, and display technologies. We have developed an aminoazobenzene material (d-MR), derived from methyl red, which forms high-quality, covalently anchored monolayers on glass. These monolayers demonstrate unusually high sensitivity to polarized light, which controls the molecular orientation distribution through optical anisotropy of the trans-cis isomerization. In an effort to understand and optimize this phenomenon we are studying the influence of the two-dimensional molecular field on the dynamics of the light-driven reorganization. We have correlated the behavior of d-MR monolayers, as determined by spectral studies of dichroism and differential reflection ellipsometry, to dilute solutions of d-MR in a variety of solvents, as characterized by absorption cross sections, quantum yields, and characteristic time constants. The resulting information has helped to clarify the details of how these molecules respond to light leading to design strategies for even higher performing monolayers. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700