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Alok Rudra

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Publications associées (84)

Magneto-optical properties of single site-controlled InGaAsN quantum wires grown on prepatterned GaAs substrates

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Romain Carron, Pascal Gallo, Marco Felici

The properties of single site-controlled InGaAsN quantum wires (QWRs)-both untreated and irradiated with atomic hydrogen-are probed by micro-magnetophotoluminescence spectroscopy. The strong anisotropy of the diamagnetic shift measured for different orient ...

2012

Bound and anti-bound biexciton in site-controlled pyramidal GaInAs/GaAs quantum dots

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Pascal Gallo, Clément William Tendaï Jarlov, Milan Calic

We present a detailed study of biexciton complexes formed in single, site-controlled pyramidal GaInAs/GaAs quantum dots (QDs). By using power dependent measurements and photon correlation spectroscopy, we identify the excitonic transitions of a large numbe ...

American Institute of Physics2012

Exciton confinement and trapping dynamics in double-graded-bandgap quantum nanowires

Elyahou Kapon, Alok Rudra, Pascal Gallo, Justyna Szeszko

We fabricate and study quantum dot structures incorporating quasi-one-dimensional excited states. The structures are realized by graded bandgap GaAs/AlGaAs quantum wires self-formed inside inverted tetrahedral pyramids. The ground state transitions exhibit ...

American Institute of Physics2012

Investigation of coherent acoustic phonons in terahertz quantum cascade laser structures using femtosecond pump-probe spectroscopy

Elyahou Kapon, Alok Rudra, Jérôme Faist, Pascal Gallo

The dynamics of acoustic vibrations in terahertz quantum cascade laser structures (THz-QCLs) is studied by means of femtosecond pump-probe spectroscopy. The phonon modes are characterized by the folding of the acoustic dispersion into an effective reduced ...

Amer Inst Physics2012

Reduced temperature sensitivity of the polarization properties of hydrogenated InGaAsN V-groove quantum wires

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Romain Carron, Marco Felici

We investigated the effects of hydrogen irradiation on the degree of linear polarization, rho, of the light emitted by site-controlled, dilute-nitride InGaAsN V-groove quantum wires (QWRs). While in the as-grown sample the polarization of the QWR emission ...

American Institute of Physics2012

Symmetries and the Polarized Optical Spectra of Exciton Complexes in Quantum Dots

Marc-André Dupertuis, Elyahou Kapon, Daniel Oberli, Alok Rudra

A systematic and simple theoretical approach is proposed to analyze true degeneracies and polarized decay patterns of exciton complexes in semiconductor quantum dots. The results provide reliable spectral signatures for efficient symmetry characterization, ...

2011

Decomposition, diffusion, and growth rate anisotropies in self-limited profiles during metalorganic vapor-phase epitaxy of seeded nanostructures

Klaus Leifer, Elyahou Kapon, Alok Rudra

We present a model for the interplay between the fundamental phenomena responsible for the formation of nanostructures by metalorganic vapor phase epitaxy on patterned (001)/(111)B GaAs substrates. Experiments have demonstrated that V-groove quantum wires ...

2011

Large mode splitting and lasing in optimally coupled photonic-crystal microcavities

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Kirill Atlasov

Coupling of L-type photonic-crystal (PhC) cavities in a geometry that follows inherent cavity field distribution is exploited for demonstrating large mode splitting of up to similar to 10-20 nm (similar to 15-30 meV) near 1 mu m wavelength. This is much la ...

Optical Society of America2011

Phonon-Mediated Coupling of InGaAs/GaAs Quantum-Dot Excitons to Photonic Crystal Cavities

Vincenzo Savona, Benjamin Dwir, Elyahou Kapon, Alok Rudra, Kirill Atlasov, Guillaume Jean Tarel, Pascal Gallo, Milan Calic

We demonstrate that the emission characteristics of site-controlled InGaAs/GaAs single quantum dots embedded in photonic crystal slab cavities correspond to single confined excitons coupled to cavity modes, unlike previous reports of similar systems based ...

2011

Symmetry Elevation and Symmetry Breaking: Keys to Describe and Explain Excitonic Complexes in Semiconductor Quantum Dots

Marc-André Dupertuis, Elyahou Kapon, Daniel Oberli, Alok Rudra

The results of a group theoretical analysis of the excitonic fine structure are presented and compared with spectroscopic data on single quantum dots. The spectral features reveal the signatures of a symmetry higher than the crystal symmetry (C-3v). A cons ...

Amer Inst Physics, 2 Huntington Quadrangle, Ste 1No1 D, Melville, Ny 11747-4501 Usa2011

Ordered systems of site-controlled pyramidal quantum dots incorporated in photonic crystal cavities

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Alessandro Surrente, Pascal Gallo, Marco Felici

The coupling of a prescribed number of site-controlled pyramidal quantum dots (QDs) with photonic crystal (PhC) cavities was studied by polarization and power-dependent photoluminescence measurements. The energy of the cavity mode could be readily tuned, m ...

Institute of Physics2011

Fine structure of exciton complexes in high-symmetry quantum dots: Effects of symmetry breaking and symmetry elevation

Marc-André Dupertuis, Elyahou Kapon, Daniel Oberli, Alok Rudra

Quantum dots (QDs) of high symmetry (e.g., C3v) have degenerate bright exciton states, unlike QDs of C2v symmetry, making them intrinsically suitable for the generation of entangled photon pairs. Deviations from C3v symmetry are detected in real QDs by pol ...

American Physical Society2010

RETRACTED: Polarization-entangled photons produced with high-symmetry site-controlled quantum dots

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Jérôme Faist, Pascal Gallo, Arun Mohan, Marco Felici

Nature Publishing Group2010

Record-Low Inhomogeneous Broadening of Site-Controlled Quantum Dots for Nanophotonics

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Jérôme Faist, Pascal Gallo, Arun Mohan, Marco Felici

Wiley-Blackwell2010

Magneto-Optical Spectroscopy Of Charged Excitonic States In Quantum Dots: Evidence Of Quantum Correlation

Elyahou Kapon, Daniel Oberli, Alok Rudra

Iop Publishing Ltd, Dirac House, Temple Back, Bristol Bs1 6Be, England2010

Pyramidal GaAs/AlzGa1-zAs quantum wire/dot systems with controlled heterostructure potential

Jean-Daniel Ganière, Elyahou Kapon, Alok Rudra, Qing Zhu

The structural and optical properties of controlled-heterostructure-potential, low-dimensional GaAs/AlGaAs nanostructures self-formed during organometallic chemical vapor deposition in tetrahedral pyramids etched in (111) B-GaAs substrates, are investigate ...

American Physical Society2010

1D photonic band formation and photon localization in finite-size photonic-crystal waveguides

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Kirill Atlasov, Pascal Gallo, Marco Felici

2010

Dense arrays of pyramidal quantum dots with narrow linewidth photoluminescence spectra

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Alessandro Surrente, Pascal Gallo, Marco Felici

Arrays of site-controlled, pyramidal InGaAs/GaAs quantum dots (QDs) grown by organo-metallic chemical vapour deposition with densities comparable to those of self-assembled QDs (5 x 109 cm(-2)) are demonstrated. The QDs exhibit high quality photoluminescen ...

2009

Photonic-crystal microcavity laser with site-controlled quantum-wire active medium

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Kirill Atlasov, Pascal Gallo, Milan Calic

Site-controlled quantum-wire photonic-crystal microcavity laser is experimentally demonstrated using optical pumping. The single-mode lasing and threshold are established based on the transient laser response, linewidth narrowing, and the details of the no ...

2009

Effect of sidewall passivation in BCl3/N2 inductively coupled plasma etching of two-dimensional GaAs photonic crystals

Benjamin Dwir, Elyahou Kapon, Alok Rudra, Kirill Atlasov, Pascal Gallo

The effect of surface passivation in BCl3/N-2 inductively coupled plasma reactive-ion etching of GaAs-based photonic crystals (PhCs) was investigated. It is shown that sidewall passivation is crucial for achieving cylindrical, vertical PhC holes, where the ...

2009

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