Femtosecond lasers and applications at Optics and Photonics 2009

Optics and Photonics Presentations attended by Del Mar Photonics team.

Femtosecond Lasers

Trestles femtosecond Ti:Sapphire laser
Trestles Finesse femtosecond Ti:Sapphire laser with integrated DPSS pump laser
Trestles Opus femtosecond Ti:Sapphire laser with built in 3 Watt DPSS laser
Teahupoo Rider femtosecond amplified Ti:Sapphire laser
Femtosecond Terawatt Ti:sapphire Laser System Teahupoo MPA-XL
Mavericks femtosecond Cr:Forsterite laser
Tamarack femtosecond fiber laser (Er-doped fiber)
Buccaneer femtosecond OA fiber laser (Er-doped fiber) and SHG
Cannon Ultra-broadband light source
Tourmaline femtosecond Yt-doped fiber laser
Yb-based high-energy fiber laser system kit, model Tourmaline Yb-ULRepRate-07
Ytterbium-doped Femtosecond Solid-State Laser Tourmaline Yb-SS400

Femtosecond lasers and applications

Saturable absorption of femtosecond laser pulses at surface plasmon resonance in gold nanoshells
Paper 7394-36 of Conference 7394
Date: Tuesday, 04 August 2009
Time: 12:35 PM – 12:55 PM

Author(s): Ida Ros, Univ. degli Studi di Padova (Italy); Piero Schiavuta, CIVEN (Italy); Renato Bozio, Giovanni Mattei, Univ. degli Studi di Padova (Italy)

In this work, we present an investigation of the nonlinear optical properties of nanoshells of different size in solutions using a single beam z-scan method at a wavelength of 806 nm with laser duration of 170 fs.
It is found that, in general, they behave as saturable absorbers, as demonstrated for other kind of nanoparticles of different metals and shapes[1-3]. The level of saturation depends on the relative overlap between the plasmon resonance of nanoshells and the laser excitation wavelengths.
An average value of the nonlinear absorption coefficient β = -3.6±1.0 x 10-11 cm/W is obtained by fitting the experimental results for core-shell particles exhibiting surface plasmon resonance at different wavelength.

(1) Elim, et al Applied Physics Letters 2006, 88, 083107.
(2) Gao, et al Optics Communications 2005, 251, 429-433.
(3) Wang, et al Applied Surface Science 2007, 253, 4673-4676.

Femtosecond pulse duration as a tool for controlling high fluence of laser filament in air
Paper 7430-31 of Conference 7430
Date: Tuesday, 04 August 2009
Time: 2:20 PM – 2:40 PM

Author(s): Elena P. Silaeva, Oleg V. Tverskoy, Valerii P. Kandidov, Lomonosov Moscow State Univ. (Russian Federation)

During propagation of high-power femtosecond laser pulse in air dynamic balance between Kerr self-focusing and laser plasma defocusing results in high localization of the energy in a hundred microns region. Stable laser filament with hundreds meters length forms. For systems of atmospheric optics it is important to control high fluence of the filament.
We investigated the influence of pulse duration and atmospheric aerosol particles scattering on energetic characteristics of the filamented laser pulse.
It was shown that increase of pulse duration causes increase of fluence and transversal size of highly localized energy area in the conditions of constant pulse energy. As a result energy of high density, transporting by pulse, and filament length increases considerably.
Statistical Monte-Carlo testing showed that energy losses caused by defocusing in plasma and multiphoton ionization and losses caused by scattering upon aerosol particles are not additive.

High Power Femtosecond Laser Systems

Wedge-M Multipass Ti:Sapphire Amplifier
Cortes 800 tabletop 40 TW Ti:Sapphire laser system
Cortes E - High vacuum laser ablation/deposition system with 2 TW Ti:Sapphire laser
Cortes K - femtosecond seed laser for Petawatt KrF excimer laser
Cortes O 200TW femtosecond laser - KD*P CPOPA based amplifier system
Jaws femtosecond Cr:forsterite Multi-Terawatt Amplified Laser
High-vacuum system for laser ablation/deposition

Parallel algorithms for numerical simulation of femtosecond laser pulse filamentation in atmosphere
Paper 7463-19 of Conference 7463
Date: Tuesday, 04 August 2009
Time: 4:10 PM – 4:30 PM

Author(s): Alexander Dergachev, Svyatoslav A. Slenov, Lomonosov Moscow State Univ. (Russian Federation)

Propagation of high-power femtosecond laser pulses in air results in their filamentation when structures much smaller than beam's diameter appear in cross-section. Numerical simulation of propagation of such pulses leads to 3D+1 problem and needs the usage of high-performance computing and 3D+parallel algorithms. Two algorithms for this problem are considered and compared. The specific feature of both algorithms is the use of non-uniform computational grid in beam's cross-section and varying step of integration along propagation direction. The ability of usage of adaptive step for parallel algorithms is considered.

Femtosecond laser fabrication of scattering medium by randomly distributed holes in polymers
Paper 7442-20 of Conference 7442
Date: Wednesday, 05 August 2009
Time: 3:10 PM – 3:30 PM

Author(s): Osamu Matoba, Yuri Kitamura, Tomoyuki Manabe, Kouichi Nitta, Kobe Univ. (Japan); Wataru Watanabe, National Institute of Advanced Industrial Science and Technology (Japan)

We have been developing a secure data storage card using a three-dimensional scattering medium. The absorbers are embedded in the scattering medium and are used as three-dimensional data. To recover the absorption distribution, one has to use the correct scattering coefficient distribution in an inverse problem as in diffuse optical tomography. In this paper, we propose a method to use many holes in a polymer as a scattering medium. Holes are fabricated by a focused femtosecond laser irradiation. We investigate experimentally and numerically the scattering characteristics of hole distributions.

Multiple time scale characterization of the nonlinear multi-photon absorption characteristics of a neat organic liquid
Paper 7413-7 of Conference 7413
Date: Sunday, 02 August 2009
Time: 10:45 AM – 11:05 AM

Author(s): Iam Choon Khoo, The Pennsylvania State Univ. (United States)

A detailed study of the nonlinear multi-photon absorption processes occurring in the femtoseconds – nanoseconds time scales in an extremely nonlinear organic neat liquid is reported. Explicit quantum chemical calculations of the molecular orbital energy levels and dipole transition strengths are combined with nonlinear transmission measurements with femto-, pico- and nano-seconds laser pulses, and transient excited state absorption spectroscopy using a nanosecond pulsed laser. The excited singlet and triplet states are responsible for enhancement of the effective nonlinear two-photon absorption of nanosecond laser pulses by the ground state. These new findings provide important corroboration of previous experimental observations of transmission switching and limiting results; they also provide useful guidelines for the development of new nonlinear molecular liquids.qA detailed study of the nonlinear multi-photon absorption processes occurring in the femtoseconds – nanoseconds time scales in an extremely nonlinear organic neat liquid is reported. Explicit quantum chemical calculations of the molecular orbital energy levels and dipole transition strengths are combined with nonlinear transmission measurements with femto-, pico- and nano-seconds laser pulses, and transient excited state absorption spectroscopy using a nanosecond pulsed laser. The excited singlet and triplet states are responsible for enhancement of the effective nonlinear two-photon absorption of nanosecond laser pulses by the ground state. These new findings provide important corroboration of previous experimental observations of transmission switching and limiting results; they also provide useful guidelines for the development of new nonlinear molecular liquids.

Ultrafast active nanoplasmonics
Paper 7392-36 of Conference 7392
Date: Tuesday, 04 August 2009
Time: 2:00 PM – 2:30 PM

Author(s): Mark I. Stockman, Georgia State Univ. (United States)

Plasmonic phenomena are ultrafast: the relaxation times of surface plasmons are on order of ten to tens femtosecond. The coherent response time of a system is defines by its inverse bandwidth and is much shorter. For metal nanoplasmonic systems the bandwidth is the entire optical spectrum from ultraviolet to near-infrared; correspondingly the response time may be as short as hundreds attoseconds. In our talk, we consider active nanoplasmonics where the optical energy on the nanoscale is controlled in time and space on femtosecond-nanometer scale. One of the focus points of our talk will be theory of spaser as an ultrafast active nanoplasmonic device: quantum generator and amplifier of nanolocalized optical energy. Other types of nonlinearly-controlled media as switches and modulators will also be considered.

Fabrication of nanoimprinting molds by two-photon polymerization
Paper 7405-14 of Conference 7405
Date: Tuesday, 04 August 2009
Time: 3:00 PM – 3:20 PM

Author(s): Wande Zhang, Li-Hsin Han, Shaochen Chen, The Univ. of Texas at Austin (United States)

Fabricating nanoimprinting molds usually involves numerous costly and time-consuming steps. We demonstrate the plausibility of making low-cost nanoimprinting molds easily by using the femtosecond-laser-induced two-photon polymerization (TPP) technique. Importantly, using TPP to make nanoimprinting modes also enables the utilization of TPP’s capacity to make fine nanoscale structures in mass production. A Ti:sapphire femtosecond laser was used to induce TPP to make 400-nm-width lines on glass substrate, our nanoimprinting mold. Poly (ethylene glycol) diacrylate was then patterned by the mold to demonstrate its imprinting capacity. The results were analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM).

Coherent ultrafast pulse synthesis between an optical parametric oscillator and a laser
Paper 7431-2 of Conference 7431
Date: Wednesday, 05 August 2009
Time: 8:30 AM – 8:50 AM

Author(s): Jinghua Sun, Derryck T. Reid, Heriot-Watt Univ. (United Kingdom)

We have demonstrated coherent optical pulse synthesis between the carrier-envelope phase-locked second-harmonic pulses from a femtosecond optical parametric oscillator and those from its Ti:sapphire pump laser. By using a single nonlinear crystal for both parametric and second-harmonic generation to achieve common-mode noise rejection, we obtained a timing jitter less than 30 attoseconds in 20 ms. Mutual coherence between the two parent pulses was verified optically by spectral interferometry, and synthesis was tested by measuring the autocorrelation of the combined pulses, with and without carrier-envelope phase locking. This system shows potential applications in sub-femtosecond pulse generation, broadband optical spectroscopy and metrology.

Applications of surface plasmon interferometry
Paper 7395-81 of Conference 7395
Date: Thursday, 06 August 2009
Time: 2:25 PM – 2:50 PM

Author(s): Vasily V. Temnov, Massachusetts Institute of Technology (United States)

Continuous wave and femtosecond time-resolved interferometric measurements with surface plasmons in a novel tilted slit-groove microinterferometer are discussed. Continuous wave measurements in magneto-optically active Gold/Cobalt/Gold multilayer films are used (i) to demonstrate manipulation of surface plasmon wave vector by applying external magnetic field and (ii) to measure skin depth at optical frequencies. Ultrafast time-resolved surface plasmon interferometry is used to monitor the dynamics of fs-laser excited hot carriers on gold surface. Unambiguous discrimination between changes in real and imaginary parts of the metal dielectric function on femtosecond time scale is demonstrated.

Nano-scale fabrication technique of three-dimensional metal structures for plasmonic metamaterials
Paper 7395-1 of Conference 7395
Date: Sunday, 02 August 2009
Time: 8:30 AM – 8:55 AM

Author(s): Takuo Tanaka, The Institute of Physical and Chemical Research (Japan) and Japan Science and Technology Agency, Presto (Japan)

Two-photon-induced metal ion reduction technique was developed for fabricating 3D metallic micro/nano structures. In this method, a near-infrared femtosecond laser is focused by a high-NA objective lens into a metal-ion in aqueous. We demonstrate the fabrication of a continuous and electrically conductive silver wire with a minimum width of 100nm. Moreover, the realization of self-supporting 3D silver microstructures is demonstrated. This technique will become a promising tool for realizing three-dimensional plasmonic metamaterials.

Organic photonic materials for all-optical signal processing and optical limiting
Paper 7413-11 of Conference 7413
Date: Sunday, 02 August 2009
Time: 1:00 PM – 1:20 PM

Author(s): Joseph W. Perry, Georgia Institute of Technology (United States)

The third-order nonlinear optical properties of several classes of conjugated materials have been investigated using femtosecond degenerate four wave mixing and Z-scan methods in the near infrared spectral region. Large third-order nonlinearities are observed for dioxaborine cyanine molecular salt thin films, polyacetylene derivatives prepared using ring-opening metathesis polymerization and zinc and lead porphyrin diacetylide polymers. Applications of these materials in all-optical switching, image recognition and optical limiting will be discussed.

Multiple filament plasma channels as a guiding system for microwave radiation in air
Paper 7463-18 of Conference 7463
Date: Monday, 03 August 2009
Time: 6:00 PM

Author(s): Alexander E. Dormidonov, Valerii P. Kandidov, Svyatoslav A. Slenov, Lomonosov Moscow State Univ. (Russian Federation)

A novel application of the high-power femtosecond laser pulse filamentation in air is introduced. Formation process of the microwave virtual guiding system from the bunch of the multiple filament plasma channels is investigated. Effective conductivity and skin layer depth of the filament plasma channels in the microwave range are calculated. Optimal spatial configurations of the plasma channels in bunch are determined corresponding to the single-wire line and cylindrical waveguide. Estimations for energy losses of microwave radiation in plasma guiding systems of different configurations are made.

The observation of nontrivial correlation and nonclassical anti-correlation of a pulsed chaotic-thermal radiation
Paper 7465-5 of Conference 7465
Date: Tuesday, 04 August 2009
Time: 4:00 PM – 4:30 PM

Author(s): Sanjit Karmakar, Zhenda Xie, Hui Chen, Yanhua Shih, Univ. of Maryland, Baltimore County (United States)

This paper reports both nontrivial spatial correlation and anti-correlation from a ~200 femtosecond pulsed chaotic-thermal light source. The classical statistical theory of intensity fluctuation correlation failed to give an adequate interpretation to explain the reported results of both correlation and anti-correlation measurements. In the view of quantum mechanics these observations are the straightforward results of two-photon interference, involving the superposition of two-photon amplitudes, a nonclassical entity corresponding to different yet indistinguishable alternative ways of triggering a joint-detection event.

Femtosecond pulse measurement instrumentation

Reef scanning and single shot femtosecond autocorrelators
Avoca SPIDER - Spectral phase interferometry for direct electric-field reconstruction (SPIDER)
Rincon third order femtosecond cross-correlator (third order autocorrelator TOAC) also referred to as contrast meter

Role of supercontinuum in the fragmentation of colloidal gold nanoparticles in solution
Paper 7405-31 of Conference 7405
Date: Wednesday, 05 August 2009
Time: 11:40 AM – 12:00 PM

Author(s): Fabian A. Videla, Univ. Nacional de la Plata (Argentina); Gustavo A. Torchia, Daniel Schinca, Lucía B. Scaffardi, Ctr. de Investigaciones Opticas (Argentina); Pablo Moreno, Cruz Méndez, Luis Roso, Univ. de Salamanca (Spain); Lisandro Giovanetti, Jose Ramallo Lopez, Univ. Nacional de la Plata (Argentina)

In this work we have studied the fragmentation of gold NPs after generation by femtosecond laser ablation in deionised water. In order to investigate the fragmentation process, we have used direct ultra-fast IR pulses and super-continuum radiation to carry out this experiments. For the purpose of assessing the effects of the different spectral bands present in the super-continuum for fragmentation, we have determined different efficiency regions analyzing the optical extinction spectrum corresponding to the initial Nps solution. We can conclude that the main mechanism correspond to linear absorption in the visible region.

A K-alpha x-ray source using high energy and high repetition rate laser system for phase contrast imaging
Paper 7451-41 of Conference 7451
Date: Wednesday, 05 August 2009
Time: 5:30 PM

Author(s): Cristina Serbanescu, Sylvain Fourmaux, Jean-Claude Kieffer, Univ. du Québec (Canada); Russell E. Kincaid, Syracuse Univ. (United States); Andrzej Krol, SUNY Upstate Medical Univ. (United States)

K-alpha x-ray sources from laser produced plasmas provide completely new possibilities for x-ray phase-contrast imaging applications. In this paper, we present a continuous and efficient Mo K-alpha x-ray source produced by a femtosecond laser system operating at 100 Hz repetition rate with maximum pulse energy of 110 mJ before compression. The source exhibits sufficient spatial coherence to observe phase contrast. Detailed characterization of the source including the x-ray spectrum and the x-ray average yield along with phase contrast images of test objects will be presented.

Course: Nanoplasmonics
Date: Thursday, 06 August 2009
Time: 8:30 AM – 5:30 PM

Instructor(s): Mark I. Stockman, Georgia State Univ. (United States)

Unique nonlinear optical properties of SiC:Ge:Fe waveguide for device applications
Paper 7420-13 of Conference 7420
Date: Sunday, 02 August 2009
Time: 2:40 PM – 3:00 PM

Author(s): Abdalla M. Darwish, Dillard Univ. (United States); Brent D. Koplitz, Tulane Univ. (United States); Hadi Alkahby, Chase Deniro, Dillard Univ. (United States)

A femtosecond pulsed laser deposition at room temperature was used to fabricate a waveguide of SiC:Ga:Ge:Fe . The waveguide was used as an optical sensor to detect the sound wave disturbance under water. It was observed that the HeNe laser drives the optical sensor to produce multiple diffraction rings, which are affected by the sound wave disturbance to produce unique clusters of rings with elongated shape pointing away from the source of the acoustic waves. It was observed that, the shape of the rings resonance with the waves to produce either constructive or destructive interference pattern which produce the elongated shape. The Sensor has the same results if it is driven by either HeNe laser or Ar ion laser. The optical characterization of the sensor under the effect of both electric field and magnetic fields and the Electron Paramagnetic Resonance of the Fe will be presented as well.

Suppressing electron-phonon coupling in quantum dot photovoltaic materials for enhanced efficiency
Paper 7411-6 of Conference 7411
Date: Sunday, 02 August 2009
Time: 4:10 PM – 4:40 PM

Author(s): Xiulin Ruan, Xianfan Xu, Purdue Univ. (United States)

We combine theory, simulation, synthesis, and characterizations to understand and tailor the hot electron relaxation through phonons in quantum dot materials including CdSe and PbTe nanocrystals, which have potentials for being used as photovoltaic materials. The non-adiabatic molecular dynamics simulations on hot electron relaxation rates clearly show that the multiphonon relaxation is slowed in low-dimensional materials. The quantum dots are synthesized with size and shape control. Femtosecond laser measurement technique is used to investigate the hot electron relaxation rate and to generate coherent phonon in these crystals, in order to study how the dot size and shape affect the energy transfer process. Experimental data support the theoretical predictions well.

Prospective schemes for next generation X-ray lasers
Paper 7451-2 of Conference 7451
Date: Tuesday, 04 August 2009
Time: 9:00 AM – 9:20 AM

Author(s): Vyacheslav N. Shlyaptsev, Lawrence Livermore National Lab. (United States); Jorge J. Rocca, Colorado State Univ. (United States)

We will discuss new approaches to produce practicable XRL at shorter wavelengths. Capillary discharge driven lasers are very successful in generating high energy soft x-ray laser pulses at 46.9 nm and longer wavelengths using 25 kA current pulses of 20-50 ns risetime. We will discuss a different regime of discharge parameters, that has the potential to specifically benefit shorter wavelength laser generation.
Another opportunity appeared recently due to the increased availability of high energy femtosecond lasers which very naturally combine with new kinds of specifically designed targets to potentially achieve larger laser pulse energy, decreased pulse duration, and shorter wavelengths.

Simultaneous spatial and temporal control of the local excitation of a nanostructure using polarization shaped laser pulses (Keynote Presentation) Paper 7394-33 of Conference 7394
Date: Tuesday, 04 August 2009
Time: 11:00 AM – 11:45 AM

Author(s): Martin Aeschlimann, Technische Univ. Kaiserslautern (Germany)

We demonstrate experimentally that polarization shaped laser pulses allow tailoring the local excitation of a nanostructure with subwavelength spatial and femtosecond temporal resolution. Time-resolved two-photon photoemission microscopy is used to monitor the local excitation of a nanostructure by a polarization shaped pump pulse. The time-resolved signal shows a significant contrast for the emission from three different regions in the emission pattern of an individual nanostructure, demonstrating a switching of the local excitation maximum in the fs time scale. The polarization-shaped laser pulses are fully characterized and thus the relationship between photoemission pattern and the transient polarization state can be determined.

Pulse compression with volume holographic transmission gratings recorded in Slavich PFG-04 emulsions
Paper 7430-32 of Conference 7430
Date: Tuesday, 04 August 2009
Time: 2:40 PM – 3:00 PM

Author(s): Ayalid M. Villamarín, Univ. de Zaragoza (Spain); Íñigo Sola, Univ. de Salamanca (Spain); Victoria Collados, Jesús Atencia, Univ. de Zaragoza (Spain); Cruz Mendez, Isabel Arias, Univ. de Salamanca (Spain); Manuel Quintanilla, Univ. de Zaragoza (Spain)

In this work we design and construct a pulse compressor with volume transmission phase holographic gratings, to compensate the second order dispersion in femtosecond laser pulses emitting at 800 nm with a spectral broadband of 10 nm.
The gratings, with a spatial frequency of 730 lines/mm, are recorded in dichromated gelatine Slavich PFG-04 emulsions with high efficiency.
We measure the factor of compression as a function of the grating distance using an autocorrelator, finding a good agreement with theoretical curve. A dispersed pulse (580 fs) is reduced to the bandwidth limited value of 100 fs with the grating pair separated by 25 mm.

Ultrafast magneto-optic switches and their applications
Paper 7420-29 of Conference 7420
Date: Tuesday, 04 August 2009
Time: 8:00 PM

Author(s): Chia-En Yang, Jimmy Yao, Yun-Ching Chang, Shizhuo Yin, The Pennsylvania State Univ. (United States)

In this paper, first, a brief review on the recent advances of ultrafast (~1 ns switching speed) magneto-optic (MO) switch based on a single domain, in-plane symmetry magnetic garnet material is presented. It shows that a high extinction ration, fast switching speed (~1 ns), an aperture size larger than 5 mm in diameter can be achieved. Second, the application of this unique switch to modulate the amplitude of the femtosecond laser pulses is also reported. It demonstrates that a very high repetition rate (>80 MHz) can potentially be achieved by employing this fast MO switch. Third, the application of this unique switch to enhance the capability of imaging through scattering media (such as fogs or clouds) is also discussed.

Holographic 3D microfabrication of line and dot array
Paper 7402-26 of Conference 7402
Date: Wednesday, 05 August 2009
Time: 3:20 PM – 3:40 PM

Author(s): Masahiro Yamaji, Hayato Kawashima, Jun'ichi Suzuki, Shuhei Tanaka, New Glass Forum (Japan)

We developed new 3D microfabrication method inside transparent materials only by using single femtosecond laser pulse of which the phase distribution is controlled by computer generated hologram. Here we show the fabrication of a complicated 3D structure; It contains a line element perpendicular to the optical axis and 24 dots arrayed as 3D spiral. In other words, this result means that elements of different aspect ratios are processed at once, which was realized only by varying the NA value of the objective lens until now. This result proves high ability of this method for bulk production of various optical devices.

Optical excitation of terahertz plasmon polaritons on a structured metal surface
Paper 7394-106 of Conference 7394
Date: Wednesday, 05 August 2009
Time: 5:30 PM

Author(s): Michael Bakunov, Maxim Tsarev, N.I. Lobachevsky State Univ. of Nizhny Novgorod (Russian Federation)

We propose to launch terahertz surface plasmon polaritons on a structured metal surface using a strip of an electro-optic material deposited on the surface. Nonlinear polarization created in the strip by a femtosecond laser pulse moves along the strip with superluminal velocity and emits plasmon polaritons via the Cherenkov radiation mechanism. The excitation is shown to be rather efficient – terahertz fields up to 10 kV/cm are generated by a 50 GW/cm2 laser pulse. The generated terahertz spectrum can be tuned by varying the incident angle of the laser pulse. The proposed technique can be used for performing terahertz surface spectroscopy.

Table-top ultrafast nanoscale imaging using coherent diffraction
Paper 7451-3 of Conference 7451
Date: Tuesday, 04 August 2009
Time: 9:20 AM – 9:40 AM

Author(s): Hamed Merdji, Commissariat à l'Énergie Atomique (France)

Imaging ultrafast energy and charge flow in hybrid plasmonic materials
Paper 7395-16 of Conference 7395
Date: Sunday, 02 August 2009
Time: 3:50 PM – 4:15 PM

Author(s): Gary P. Wiederrecht, Yugang G. Sun, Argonne National Lab. (United States); Alexandre Bouhelier, Univ. de Bourgogne (United States); Gregory A. Wurtz, Univ. of North Florida (United States)

Hybrid nanostructures consisting of molecular and plasmonic materials with strongly coupled electronic states can produce new optical states and energy decay pathways. In this talk, we discuss our recent studies of electromagnetic coupling and associated temporal dynamics of molecular excitations with plasmonic resonances supported by either localized or extended planar geometries. We focus on coherent interactions between plasmon resonances and molecular excitations, which are experimentally challenging due to the very short (~10-100 fs) coherence times of plasmons. Recent experimental results and theoretical analysis for observing and controlling coherences between molecular excitations and plasmonic polarizations are shown.

Ultrafast molecular photonics
Paper 7415-21 of Conference 7415
Date: Sunday, 02 August 2009
Time: 5:05 PM – 5:25 PM

Author(s): Guglielmo Lanzani, Politecnico di Milano (Italy)

Plastic media such as amplifiers and optical fibers may have a role in future telecommunications and data communication in local area networks, automotive and inter board connections. Plastics photonics devices may consist of the transmission medium, typically PMMA, doped by the active material and chips based on integrated devices and waveguides. We will report on properties and performances of active media based on conjugated molecules and polymers (CP) in different architectures and morphologies. Correlation between the polymer chain network and the performances will be presented based on ultrafast spectroscopy data. Photonic control of the molecular conformation will be demonstrated as a route towards molecular photonics.

Ultrafast carrier dynamics in semiconductor nanowires
Paper 7406-13 of Conference 7406
Date: Tuesday, 04 August 2009
Time: 8:30 AM – 9:00 AM

Author(s): Rohit P. Prasankumar, Los Alamos National Lab. (United States)

Semiconductor nanowires have recently attracted much interest due to their novel electronic and optical properties, along with their potential for device applications in areas including nanoscale lasers and thermoelectrics. However, the further development and optimization of nanowire-based devices will depend critically on an understanding of carrier relaxation in these unique nanostructures. Here, some of the first ultrafast wavelength-tunable (ultraviolet to terahertz) spectroscopic measurements of carrier dynamics in semiconductor nanowires will be presented, revealing novel phenomena resulting from the two dimensional confinement of electrons and holes and enhanced influence of surface and defect states.

Femtosecond Lasers

Table-top ultrafast nanoscale imaging using coherent diffraction
Paper 7451-3 of Conference 7451
Date: Tuesday, 04 August 2009
Time: 9:20 AM – 9:40 AM

Author(s): Hamed Merdji, Commissariat à l'Énergie Atomique (France)

Coherent diffraction allows imaging non-crystalline objects and leads actually to a strong impact in science. In 2006, the first single shot ultrafast coherent diffraction pattern was measured on isolated non-periodic nano-sample [Chapman et al., Nature Physics 2006]. Laser-driven ultrashort coherent X-ray sources offer a comparatively inexpensive alternative. In this work we use a very intense high harmonic generation source, at the microjoule level, driven in enhanced phase-matching conditions by a standard femtosecond laser. Diffraction patterns of isolated objects are obtained in single shot. Our set-up reaches a resolution of 62 nm and potentially a time resolution of 20 femtoseconds.

Ultrafast demagnetization induced by interlayer spin angular momentum transfer
Paper 7398-25 of Conference 7398
Date: Tuesday, 04 August 2009
Time: 11:00 AM – 11:30 AM

Author(s): Gregory Malinowski, Univ. Konstanz (Germany); Francesco Dalla Longa, Jeroen H. H. Rietjens, Paresh V. Paluskar, Roeland Huijink, Henk J. M. Swagten, Bert Koopmans, Technische Univ. Eindhoven (Netherlands)

Recently, spin dynamics on the sub-picosecond timescale has become one of the most exciting areas in magnetism. After being excited by a strong laser pulse (~100 fs), magnetization of a ferromagnetic thin film can be (partially) quenched. This process relies on spin angular momentum transfer to another part of the system. Here, we demonstrate the possibility to speed up the sub-ps demagnetization after laser excitation by controlling the spin angular momentum dissipation in Co/Pt multilayers.

Ultrafast properties of gold-nanoshell/J-aggregate complexes
Paper 7394-34 of Conference 7394
Date: Tuesday, 04 August 2009
Time: 11:45 AM – 12:05 PM

Author(s): Nche T. Fofang, Nathaniel K. Grady, Tae-Ho Park, Peter J. Nordlander, Naomi J. Halas, Rice Univ. (United States)

Ultrafast active nanoplasmonics
Paper 7392-36 of Conference 7392
Date: Tuesday, 04 August 2009
Time: 2:00 PM – 2:30 PM

Author(s): Mark I. Stockman, Georgia State Univ. (United States)

Plasmonic phenomena are ultrafast: the relaxation times of surface plasmons are on order of ten to tens femtosecond. The coherent response time of a system is defines by its inverse bandwidth and is much shorter. For metal nanoplasmonic systems the bandwidth is the entire optical spectrum from ultraviolet to near-infrared; correspondingly the response time may be as short as hundreds attoseconds. In our talk, we consider active nanoplasmonics where the optical energy on the nanoscale is controlled in time and space on femtosecond-nanometer scale. One of the focus points of our talk will be theory of spaser as an ultrafast active nanoplasmonic device: quantum generator and amplifier of nanolocalized optical energy. Other types of nonlinearly-controlled media as switches and modulators will also be considered.

Release of multiple species from gold nanorods by ultrafast laser excitation
Paper 7397-14 of Conference 7397
Date: Tuesday, 04 August 2009
Time: 3:00 PM – 3:30 PM

Author(s): Kimberly S. Hamad-Schifferli, Massachusetts Institute of Technology (United States)

We demonstrate the use of gold nanorods to control the release of multiple species independently. Ultrafast laser excitation at the nanorod longitudinal surface plasmon resonance (SPR) heats the nanorod to a high local temperature, inducing melting, which can release biomolecules conjugated to the nanorod. Because the SPR is tunable by changing nanorod aspect ratio, nanorods with different aspect ratios can be excited independently at different wavelengths. We exploit this property for selective and mutually exclusive release of two distinct DNA oligonucleotides, and show that the released DNA is still functional. Tuning laser fluence can tune release efficiency. Thus, triggered release from nanorods is potentially powerful for improving drug delivery strategies.

Ultrafast magneto-optic switches and their applications
Paper 7420-29 of Conference 7420
Date: Tuesday, 04 August 2009
Time: 8:00 PM

Author(s): Chia-En Yang, Jimmy Yao, Yun-Ching Chang, Shizhuo Yin, The Pennsylvania State Univ. (United States)

In this paper, first, a brief review on the recent advances of ultrafast (~1 ns switching speed) magneto-optic (MO) switch based on a single domain, in-plane symmetry magnetic garnet material is presented. It shows that a high extinction ration, fast switching speed (~1 ns), an aperture size larger than 5 mm in diameter can be achieved. Second, the application of this unique switch to modulate the amplitude of the femtosecond laser pulses is also reported. It demonstrates that a very high repetition rate (>80 MHz) can potentially be achieved by employing this fast MO switch. Third, the application of this unique switch to enhance the capability of imaging through scattering media (such as fogs or clouds) is also discussed.

Coherent ultrafast pulse synthesis between an optical parametric oscillator and a laser
Paper 7431-2 of Conference 7431
Date: Wednesday, 05 August 2009
Time: 8:30 AM – 8:50 AM

Author(s): Jinghua Sun, Derryck T. Reid, Heriot-Watt Univ. (United Kingdom)

We have demonstrated coherent optical pulse synthesis between the carrier-envelope phase-locked second-harmonic pulses from a femtosecond optical parametric oscillator and those from its Ti:sapphire pump laser. By using a single nonlinear crystal for both parametric and second-harmonic generation to achieve common-mode noise rejection, we obtained a timing jitter less than 30 attoseconds in 20 ms. Mutual coherence between the two parent pulses was verified optically by spectral interferometry, and synthesis was tested by measuring the autocorrelation of the combined pulses, with and without carrier-envelope phase locking. This system shows potential applications in sub-femtosecond pulse generation, broadband optical spectroscopy and metrology.

Compact ultrafast gigahertz repetition rate lasers for frequency comb generation
Paper 7431-3 of Conference 7431
Date: Wednesday, 05 August 2009
Time: 8:50 AM – 9:10 AM

Author(s): Thomas Südmeyer, A. E. H. Oehler, D. J. H. C. Maas, B. Rudin, Aude-Reine Bellancourt, M. Hoffmann, Y. Barbarin, M. Golling, U. Keller, ETH Zürich (Switzerland)

Frequency combs with multi-GHz spectral spacing are important for numerous applications in science and metrology. We present compact ultrafast diode-pumped lasers, which are an excellent alternative to complex and expensive titanium-sapphire lasers. We present a fundamentally mode-locked Er:Yb:glass laser operating at a record-high repetition rate of 101 GHz. Ultrafast vertical external cavity surface-emitting lasers (VECSELs) are another promising alternative, which currently reach 50 GHz at 102 mW. We then discuss the MIXSEL, a novel ultrafast VECSEL with integrated saturable absorber for pulse formation. The MIXSEL achieves modelocking in a simple, straight cavity and appears suitable for wafer-scale, cost-efficient mass production.

Ultrafast light transmission behavior of surface plasmon excited Maxwell-Garnet type Ag nanocomposite polymer
Paper 7394-78 of Conference 7394
Date: Wednesday, 05 August 2009
Time: 5:30 PM

Author(s): Karthikeyan Balasubramanian, National Institute of Technology, Tiruchirappalli (India); Suchand C. S. Sandeep, Reji Philip, Raman Research Institute (India)

In the present study, metal ions are incorporated into Poly vinyl alcohol polymer through the polyol chemical method. In this technique the AgNO3 and PVA solutions are mixed together and kept in petri dishes under ambient conditions. Optical absorption spectral studies show that the surface plasmon resonance maximum of the Ag clusters is around 420 nm. To measure the near-resonant optical nonlinearity in the samples, open aperture z-scan measurements are done at 400 nm, using ultrashort laser pulses of 100 fs pulsewidth (FWHM) for excitation. The results are analyzed based on the effective medium approach

Lithographic scaling in silicon photonics: Is smaller better?
Paper 7402-15 of Conference 7402
Date: Wednesday, 05 August 2009
Time: 10:30 AM – 11:00 AM

Author(s): Michael Hochberg, Thomas W. Baehr-Jones, Univ. of Washington (United States)

Silicon has recently been used to build chip-scale optical and optoelectronic
devices, using the same nanoscale fabrication processes used to make transistor-based
electronic chips. Systems with thousands of optical components, integrated
together on the same chip with electronics, have been demonstrated, primarily for
applications in data communications. Foundry processes and shared shuttle runs
are just beginning to become available for simple photonic process flows,
dramatically lowering the cost of entry in the field.
Convenient wavelengths for silicon photonics are in the near-infrared, so the
feature sizes of devices have typically been in the hundreds of nanometers to
microns. There is, however, enormous promise in creating truly nanostructured
waveguides for applications in ultrafast nonlinear optics. Because of the ability to
build sub-50 nm structures, it is possible to greatly enhance nonlinear optical
effects and to construct complex, low-power, ultrafast optical devices and
systems. Though it is not intuitively obvious that it should be so, it turns out that,
much like with electronics, performance scales inversely with feature size for
many applications.
By taking advantage of the ability to create nanoscale features within the
waveguides, we can control the flow and concentration of optical fields with
exquisite precision. It is thus possible to build structures that take advantage of
both silicon fabrication technology and synthetic nonlinear optical materials in
order to create chip-scale optical systems with enormously enhanced
nonlinearities.
This talk will review the state of the field and will present a number of recent
silicon nanophotonic devices results, including low-voltage electrooptic
modulators and all-optical ultrafast modulators. Furthermore, opportunities for
order-of-magnitude improvements in performance that will emerge from the
ability to build extremely small (~20 nm and below) structures will be discussed.

Investigation of ultrafast carrier dynamics in ZnO rods using two-photon emission and second-harmonic generation microscopy
Paper 7396-12 of Conference 7396
Date: Monday, 03 August 2009
Time: 4:30 PM – 5:00 PM

Author(s): John M. Papanikolas, The Univ. of North Carolina at Chapel Hill (United States)

Zinc oxide is a wide band gap semiconductor with a large non-linear susceptibility that can assume a variety of complex geometrical architectures. It is the combination of material characteristics and structural diversity that makes ZnO an ideal candidate for new optoelectronic and photonic applications that are designed to exploit both the optical properties of the material and the shape of the object. We have utilized near-infrared two-photon emission and second-harmonic generation (SHG) microscopy to investigate (1) optical second-harmonic generation and (2) ultrafast photoinduced carrier dynamics in individual ZnO rods.

Interfacial molecular and electronic structure at fullerene-donor heterojunctions
Paper 7396-18 of Conference 7396
Date: Tuesday, 04 August 2009
Time: 10:40 AM – 11:10 AM

Author(s): Steven W. Robey, National Institute of Standards and Technology (United States)

Controlling the molecular and electronic structure that dominates charge separation and recombination processes at donor-acceptor interfaces is critical for achieving optimal efficiencies in organic photovoltaic systems. Technologically relevant donor-acceptor interfaces were studied using a combination of STM/STS to investigate molecular structure and photoemission/ultrafast two-photon photoemission methods to provide information on interfacial electronic structure and charge dynamics. We will discuss formation of C60/pentacene interfaces that develop distinctly different molecular structure depending on conditions and deposition sequence. We will also discuss studies of electron/exciton dynamics at copper phthalocyanine/C60 interfaces using two-photon photoemission to observe ultrafast electron transfer from CuPc into C60.

Electric field assisted charge separation at the interface between electron donor and acceptor in an organic photovoltaic blend
Paper 7396-26 of Conference 7396
Date: Tuesday, 04 August 2009
Time: 5:20 PM – 5:40 PM

Author(s): Ryan Pensack, Larry W. Barbour, Maureen Hegadorn, John B. Asbury, The Pennsylvania State Univ. (United States)

Ultrafast two-dimensional infrared and visible pump – infrared probe spectroscopic techniques are used to examine the dynamics of photoinduced charge separation in an organic photovoltaic blend. The carbonyl (C=O) stretch of PCBM is probed as a local vibrational reporter of the dynamics in a blend with a conjugated polymer, CN-MEH-PPV. Following interfacial electron transfer, geminate electron – hole pair dissociation occurs on ultrafast timescales from 100 fs to 10 ps. These fast dynamics suggest that the presence of an interfacial dipole causes the charge carriers to experience a smaller Coulombic potential than would be predicted from the dielectric properties of the materials.

Electric field assisted charge separation at the interface between electron donor and acceptor in an organic photovoltaic blend
Paper 7416-26 of Conference 7416
Date: Tuesday, 04 August 2009
Time: 5:20 PM – 5:40 PM

Author(s): Ryan Pensack, Larry W. Barbour, Maureen Hegadorn, John B. Asbury, The Pennsylvania State Univ. (United States)

Ultrafast two-dimensional infrared and visible pump – infrared probe spectroscopic techniques are used to examine the dynamics of photoinduced charge separation in an organic photovoltaic blend. The carbonyl (C=O) stretch of PCBM is probed as a local vibrational reporter of the dynamics in a blend with a conjugated polymer, CN-MEH-PPV. Following interfacial electron transfer, geminate electron – hole pair dissociation occurs on ultrafast timescales from 100 fs to 10 ps. These fast dynamics suggest that the presence of an interfacial dipole causes the charge carriers to experience a smaller Coulombic potential than would be predicted from the dielectric properties of the materials.

Dynamics on the nanoscale: time-domain ab initio studies of quantum dots and carbon nanotubes
Paper 7396-1 of Conference 7396
Date: Sunday, 02 August 2009
Time: 3:30 PM – 4:00 PM

Author(s): Oleg V. Prezhdo, Univ. of Washington (United States)

Device miniaturization requires an understanding of the dynamical response of materials on the nanometer scale. A great deal of experimental and theoretical work has been devoted to characterizing the excitation, charge, spin, and vibrational dynamics in a variety of novel materials, including carbon nanotubes, quantum dots, conducting polymers, inorganic semiconductors and molecular chromophores. We have developed state-of-the-art non-adiabatic molecular dynamics techniques and implemented them within time-dependent density functional theory in order to model the ultrafast photoinduced processes in these materials at the atomistic level, and in real time.

Time-resolved spin transfer torque dynamics: from coherent control to ballistic magnetization reversal
Paper 7398-24 of Conference 7398
Date: Tuesday, 04 August 2009
Time: 10:30 AM – 11:00 AM

Author(s): Santiago Serrano Guisan, Physikalisch-Technische Bundesanstalt (Germany); Karsten Rott, Gunter Reiss, Univ. Bielefeld (Germany); Hans-Werner Schumacher, Physikalisch-Technische Bundesanstalt (Germany)

Magnetization precession and magnetization reversal in a magnetic multilayer nanostructure can be induced by spin transfer torque (STT) resulting from a spin-polarized current through the device. However, STT magnetization reversal by ultra short current pulses can leave the magnetization, after reversal, in a precessional motion (the so-called magnetization ringing) which can take several nanoseconds to decay. By adapting the duration of the current pulse to the STT precession period of the magnetization we are able to suppress the magnetization ringing and observe ultrafast ballistic STT magnetization reversal which is essential for fast and reliable future non volatile magnetic memory devices.

Course: Nanoplasmonics
Date: Thursday, 06 August 2009
Time: 8:30 AM – 5:30 PM

Instructor(s): Mark I. Stockman, Georgia State Univ. (United States)

Dynamics and multiphoton absorption properties of chromophore functionalized metal and semiconductor nanomaterials
Paper 7413-9 of Conference 7413
Date: Sunday, 02 August 2009
Time: 11:05 AM – 11:25 AM

Author(s): Rama Krishna Guda, Western Michigan Univ. (United States)

Multiphoton absorption properties and dynamics of chromophore functionalized semiconductor and metal nanoparticles are investigated in our group in an effort to understand how the interfacial electron and energy transfer properties influence the nonlinear optical properties. In this presentation, results on alizarin and quinizarin chromophores complexed with TiO2, ZrO2 and ZnO will be discussed with reference to multiphoton properties and ultrafast dynamics. In addition, results on Coumarin-343 and riboflavin sensitized wide band gap semiconductor nanoparticles which showed enhanced multiphoton cross-sections on the surface of semiconductor nanoparticles will be presented. Results on chromophores functionalized gold clusters will also be discussed which will provide the insights into quantum size effects and surface plasmon influence on multiphoton properties.

Electric field modulated directional energy flow in strongly-coupled quantum dot nano-assemblies
Paper 7393-9 of Conference 7393
Date: Sunday, 02 August 2009
Time: 12:00 PM – 12:20 PM

Author(s): Yashwant K. Verma, Somnath Ghosh, Maribel Gallardo, Christopher G. Ferri, Sayantani Ghosh, Univ. of California, Merced (United States)

We report about our technique of creating macroscopically ordered aggregates of strongly-coupled disk-shaped colloidal QDs by suspending them in a matrix of nematic liquid-crystal molecules (NLC) at room-temperatures. High resolution ultrafast optical spectroscopy reveals the strength of the interdot coupling to be far greater than previously observed in other colloidal QDs. AFM images have demonstrated that aggregation occurs by stacking of the disk-shaped QDs, while DLS measurements on isolated and QD-NLC matrix reveal the aggregates to be composed of tens of QDs. Liquid-crystal molecules allow us to reversibly alter the spatial orientation of the coupled QDS in situ by application of electric fields. The electrical modulation, which controllably alters the directionality of energy flow along preferred axes, is an important functionality for applications in opto-electronic devices.
This work was supported by ARO.

Improved efficiency of materials processing by dual action of XUV/Vis-NIR ultrashort laser pulses and comprehensive study of high-order harmonic XUV source at PALS
Paper 7448-4 of Conference 7448
Date: Monday, 03 August 2009
Time: 9:40 AM – 10:00 AM

Author(s): Krzysztof Jakubczak, Tomas Mocek, Bedrich Rus, Jan Hrebicek, Magdalena Sawicka, Institute of Physics (Czech Republic); I Jong Kim, Chul Min Kim, Gye Hwang Lee, Chang Hee Nam, Korea Advanced Institute of Science and Technology (Korea, Republic of); Jaromir Chalupsky, Vera Hajkova, Libor Juha, Institute of Physics (Czech Republic); Jaroslav Sobota, Tomas Forst, Institute of Scientific Instruments (Czech Republic)

We demonstrate a novel experimental method for improving the efficiency of structural surface modification of various solids (PMMA, amorphous carbon) achieved by simultaneous action of XUV (21.6 nm), obtained from high-order harmonic generation (HHG), and Vis-NIR (410/820 nm) laser pulses. Although the fluence of each individual pulse was far below the surface ablation threshold, very efficient and specific material modification was observed after irradiation by a few shots of XUV/Vis-NIR radiation. Laser induced periodic surface structures were easily generated using this technique.
We also report on comprehensive characterization of ultrafast, coherent XUV beamline. The beamline is based on 1 kHz, table-top, high-order harmonic generation source capable of delivering fully coherent beam in the 30 nm spectral range. Beam profile, divergence, transversal coherences, spectral characteristics, tunability, and focusability were investigated.

Plasmonic enhancement of excitonic solar cells
Paper 7411-13 of Conference 7411
Date: Monday, 03 August 2009
Time: 10:40 AM – 11:10 AM

Author(s): Jao van de Lagemaat, Thomas H. Reilly III, Anthony J. Morfa, National Renewable Energy Lab. (United States); Allison C. Kanarr, Univ. of Colorado at Boulder (United States); Justin C. Johnson, National Renewable Energy Lab. (United States)

This work will discuss recent results on the use of plasmonically active electrodes in excitonic solar cells. It will be shown that the inclusion of such electrodes can significantly enhance solar-energy conversion. Secondly, we will discuss fundamental studies using ultrafast transient absorbance spectroscopy of plasmon-exciton hybridization in systems consisting of molecular absorbers such as pentacene on top of nanoscale silver. The dynamics of both triplet formation and decay are significantly altered due to coupling of the triplet excitation to a resonant surface plasmon, indicating a potential use of surface plasmon coupling in 3rd generation solar conversion.

Plasmonic enhancement of excitonic solar cells
Paper 7416-13 of Conference 7416
Date: Monday, 03 August 2009
Time: 10:40 AM – 11:10 AM

Author(s): Jao van de Lagemaat, Thomas H. Reilly III, Anthony J. Morfa, National Renewable Energy Lab. (United States); Allison C. Kanarr, Univ. of Colorado at Boulder (United States); Justin C. Johnson, National Renewable Energy Lab. (United States)

This work will discuss recent results on the use of plasmonically active electrodes in excitonic solar cells. It will be shown that the inclusion of such electrodes can significantly enhance solar-energy conversion. Secondly, we will discuss fundamental studies using ultrafast transient absorbance spectroscopy of plasmon-exciton hybridization in systems consisting of molecular absorbers such as pentacene on top of nanoscale silver. The dynamics of both triplet formation and decay are significantly altered due to coupling of the triplet excitation to a resonant surface plasmon, indicating a potential use of surface plasmon coupling in 3rd generation solar conversion.

Optical frequency combs: looking toward optical frequency measurements at the 10-18 level
Paper 7431-1 of Conference 7431
Date: Wednesday, 05 August 2009
Time: 8:00 AM – 8:30 AM

Author(s): Tara M. Fortier, National Institute of Standards and Technology (United States)

Optical frequency combs have become an integral part of optical clock technology, length measurement and optical frequency metrology [1]. With an increasing number of applications requiring more stringent instability of these optical comb systems, two questions loom on the horizon: how reliable can optical frequency combs based on Ti:sapphire be made, and what instabilities can we hope to achieve? In this paper we will present some of the engineering, optical and electronic details we have undertaken at NIST, Boulder to make optical frequency combs based on Ti:sapphire more robust and more stable.

[1] J.L. Hall. Defining and measuring optical frequencies. Nobel Lecture, 8 Dec. 2005

Femtosecond Lasers

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Nanoptical characterization of plasmonic nanostructures and devices with single and multiprobe NSOM (Keynote Presentation)
Paper 7394-1 of Conference 7394
Date: Sunday, 02 August 2009
Time: 8:30 AM – 9:15 AM

Author(s): Aaron Lewis, The Hebrew Univ. of Jerusalem (Israel)