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Friday, August 15 • 08:30 - 10:30
Optical Properties of Heterostructures V

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8:30-9:00

Invited: Gaël Nardin
Multidimensional Coherent Spectroscopy of Semiconductor Nanostructures
Co-authors: Travis Autry, Galan Moody, Rohan Singh, Hebin Li, François Morier-Genoud, Kevin Silverman, Steven Cundiff

Multidimensional coherent spectroscopy (MDCS) is an extension of Four-Wave-Mixing (FWM) techniques, which enables the unfolding of one-dimensional spectra onto, e.g., absorption and emission energy axes. It is an ideal tool to visualize and investigate coupling mechanisms in semiconductor materials [1], and it enables the separation of homogeneous and inhomogeneous line widths of a resonance [2]. In this talk, two approaches are presented.

The first approach is a non-collinear technique, which relies on the directional selection of the radiated FWM signal. As an example, a study of coupling between InGaAs quantum wells is presented. It exemplifies the ability of MDCS to distinguish quantum coupling from polarization interferences. A unique collection of zero-, one- and two-quantum spectra reveals two contributions---coherent and incoherent---to the inter-well coupling. Excellent agreement with density matrix simulations allows us to attribute the origin of the coherent coupling signatures to many-body effects, in the form of a renormalization of two-exciton states [1]. This new perspective on the coupling mechanism in semiconductor QWs may help in understanding the role played by many-body effects in devices where the inter-well coupling is exploited, such as quantum cascade lasers.

The drawback of non-collinear techniques is that they rely on the conservation of momentum, and thus cannot be applied to study single or few nanostructures whose size are below the diffraction limit. We present a second approach, based on a collinear geometry and the detection of the FWM as a photocurrent signal. It relies on the individual acousto-optic modulation of four excitation pulses, and selection of the FWM signal in the frequency domain [3]. The technique can be used to realize MDCS of single sub-diffraction nanostructures, and is therefore adapted to the study of building blocks of optoelectronics devices, such as single quantum dots or carbon nanotubes in diode structures. The robustness of the detection scheme enables the detection of amplitude and phase of the non-linear signal without requiring active stabilization. We demonstrate the technique by recording two-dimensional spectra from quantum well excitons in a p-i-n diode.

[1] Nardin et al, Phys. Rev. Lett. 112, 046402 (2014).
[2] Singh et al, Phys. Rev. B, 88, 045304 (2013).
[3] Nardin et al, Optics Express, 21, 28617 (2013).

The work at JILA was primarily supported by the U.S. Department of Energy under Award No. DE-FG02- 02ER15346, as well NIST. G. N. acknowledges support by the Swiss National Science Foundation (SNSF).

9:00-9:15
Oral: Faina Esser
Spectroscopic Investigation in High Magnetic Fields of the Dilute Nitride GaAsN
Co-authors: Oleksiy Drachenko, Harald Schneider, Amalia Patané, Mark Hopkinson, Manfred Helm

9:15-9:30
Oral: Scott Dufferwiel
Strong Exciton-Photon Coupling in Open Microcavities
Co-authors: Francois Fras, Aurelien Trichet, Feng Li, Laurynas Giriunas, Maxim N. Makhonin, Paul M. Walker, Luke R. Wilson, Jason M. Smith, Dimitrii N. Krizhanovskii, Maurice S. Skolnick

9:30-9:45
Oral: Savvas Germanis
Stark Effect on the Emission of a Single Piezoelectric InAs Quantum Dot at Liquid Nitrogen Temperature
Co-authors: Charalambos Katsidis, Antonis Stavrinidis, Simeon Tsintzos, George Constantinidis, Zacharias Hatzopoulos, Nikos Pelekanos

9:45-10:00
Oral: Alex Hayat
Dynamic StarkEeffect in Strongly Coupled Microcavity Exciton Polaritons
Co-authors: Christoph Lange, Lee Rozema, Ardavan Darabi, Henry van Driel, Aephraim Steinberg, Bryan Nelsen, David Snoke, Loren Pfeiffer, Kenneth West

10:00-10:15
Oral: Lily Yang
Narrow Emission Linewidths from Site-Controlled Self Assembled GaAs Quantum Dots
Co-authors: Michael Yakes, Allan Bracker, Timothy Sweeney, Peter Brereton, Mijin Kim, Chulsoo Kim, Patrick Vora, Doewon Park, Samuel Carter, Daniel Gammon

10:15-10:30
Oral: Ping Yu
Effect of Vertical & Lateral Coupling on Optical Properties of InGaAs Quantum Dots 
Co-authors: Meera Chandrasekhar, H.R. Chandrasekhar 

Session Chairs
AG

Alejandro González-Tudela

Max Planck Institute of Quantum Optics

Speakers
GN

Gaël Nardin

University of Colorado & NIST
Gael Nardin completed his PhD thesis at EPFL, at the Laboratory of Quantum Optoelectronics. He developed and used time-resolved interferometric imaging techniques to study the dynamics of exciton polaritons in semiconductor microcavities. He is now a post-doctoral research associate at JILA, implementing a novel concept of coherent multi-dimensional spectroscopy to study low-dimensional semiconductor nanostructures.


Friday August 15, 2014 08:30 - 10:30
Room 16A

Attendees (11)