Publications de Elyahou Kapon | EPFL Graph Search

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A widely-tunable single-mode 1.3 mu m vertical-cavity surface-emitting laser structure incorporating a microelectromechanical system-tunable high-index-contrast subwavelength grating (HCG) mirror is suggested and numerically investigated. A linear tuning r ...

We report on the direct absorption measurement of the polarization selection rules in a V-groove QWR waveguide. Attenuation measurements in a 1 mm long waveguide were performed from 10 K up to room temperature. These measurements yielded the QWR DOS selection rules for lateral (TE) and vertical (TM) confinement directions. 1D heavy-hole like e(n)h(n) subband features were observed in the TE absorption spectra. Effective mass and 4 x 4 k . p models have been used to evaluate the band to band absorption. For

We report on the effects of optical disorder on breaking the symmetry of the cavity modes of H-3 photonic crystal cavities incorporating site-controlled pyramidal quantum dots (QDs) as the internal light source. The high in-plane symmetry of the polarizati ...

investigate the use of MOVPE-grown ordered nanostructures on non-planar substrates for quantum nano-photonics and quantum electrodynamics-based applications. The mastering of surface adatom fluxes on patterned GaAs substrates allows for forming nanostrucutres confining well-defined charge carrier states. An example given is the formation of quantum dot (QD) molecules tunneled-coupled by quantum wires (QWRs), in which both electron and hole states are hybridized. In addition, it is shown that the high degree

We have measured the temperature dependence of the conductance of long V-groove quantum wires fabricated using GaAs/AlGaAs heterostructures, in a wide temperature range (200 mK < T < 4.2 K). We find that for our quantum wires the Fermi velocity can be as l ...

Carrier transport and capture paths via barriers of different dimensionality in AlGaAs/GaAs quantum wire (QWR)/quantum dot (QD) heterostructures, grown in inverted pyramids, are studied by photoluminescence (PL) spectroscopy. Evidence for thermally activated diffusion related to potential disorder in the QWR barriers and thermionic emission of carriers from the QD into the QWR barrier is observed in temperature dependent PL spectra. Similar activation energies for the thermionic emission are derived from th

We have studied the capabilities of chemical beam epitaxy (CBE) to produce high-gain media for long-wavelength (1.5 mu m) vertical cavity surface emitting lasers (VCSELs). Using a parameter pair of low growth temperature and small V/III ratio the integration of up to 15 highly strained (1.78%) InAsP quantum wells (QWs) into a periodic gain structure (PGS) is successfully demonstrated. In this work we present data of atomic force microscopy (AFM), X-ray diffraction, reflectivity and electro-luminescence meas

The optical properties of high-quality V-groove GaAs/AlxGa1-xAs quantum wires have been investigated using low-temperature photoluminescence (PL) and photoluminescence excitation (PLE) techniques. We systematically study the evolution of PL and PLE spectra as a function of the wire size. This comparison allows us to analyze the modification of one-dimensional subbands with decreasing win thickness. We clarify the influence of surface corrugation and localization effects on PL and PLE spectra and we observe

This paper reports on a numerical analysis of methods for current injection into AlInGaAs/InP tunnel-junction electrically pumped vertical-external-cavity surface-emitting lasers. The tunnel junction is patterned to minimize the current crowding effect and ...

Optoelectronic properties of site-controlled AlGaAs/GaAs quasi-one-dimensional structures are investigated. Controllable linear variation of the band gap along the vertical axis of the quantum wire, symmetrical with respect to its center, results in a set ...

Strong optical confinement implemented with 2D photonic-crystal (PhC) microcavities provides a powerful tool for controlling the features of light-matter interaction. Combined with nanostructures such as quantum wells, quantum wires (QVTRs) or quantum dots, the PhC cavities - efficiently controlling spontaneous emission [1] are envisaged to bring superior semiconductor-laser performance [2], which could be exploited for applications in low-power-consumption integrated optoelectronics. Furthermore, inter-cav

We report coupled VCSEL arrays, emitting at 1.3μm wavelength, in which both the optical gain/loss and refractive index distributions were defined on different vertical layers. The arrays were electrically pumped through a patterned tunnel junction, whereas the array pixels were realized by intra-cavity patterning using sub-wavelength air gaps. Stable oscillations in coupled modes were evidenced for 2x2 array structures, from threshold current up to thermal roll-over, using spectrally resolved field pattern

Intraband photocurrent spectroscopy of site-controlled pyramidal quantum dots by inserting them into the intrinsic region of n-i-n like quantum dot infrared photodetector structure is reported. The photovoltaic response is observed in the mid-infrared regi ...

We investigate experimentally and theoretically the impact of valence band mixing and spectrum of confined states on the polarization of light emitted from or absorbed by GaAs/AlGaAs semiconductor quantum dots and quantum wires with tailored heterostructur ...

The electronic states in the conduction and valence bands of quantum wires are studied by means of the effective mass hamiltonian and the Luttinger hamiltonian. The band mixing effects due to the wire geometry are fully taken into account by an accurate finite element solution of the resulting Schrodinger equations. The quantum wire profiles measured by transmission electron microscopy are used. The comparison of theoretical results with photoluminescence excitation spectra of various nanostructures yields

Optically pumped vertical external cavity surface emitting lasers (VECSELs) based on flip-chip gain mirrors emitting at the 1.55 mu m wavelength range are reported. The gain mirrors employ wafer-fused InAlGaAs/InP quantum well heterostructures and GaAs/AlA ...

The photoluminescence (PL) and PL-excitation (PLE) spectra of InyCa1-yAs/AlxGa1-xAs compressively strained V-groove quantum wires (QWR's) are compared to that of lattice-matched GaAs/AlyGa1-xAs QWR's with the same wire geometry. The PL is preferentially polarized along the QWR axis and the PL anisotropy increases with increasing indium content y. The observed PLE anisotropy also increases with y at the ground subband transition but is nearly independent of excited subband indices, unlike the case of lattice

The role of the confinement potential symmetry on the electronic and optical properties of quantum mires is systematically studied. In a wide class of quantum mires with mirror symmetry we evidence a new set of optical transitions resulting both from band mixing and Ct, symmetry breaking at zone center. Several kinds of quasi-one-dimensional excitons are predicted as well as their specific dipole coupling. Even for ultralow C-1 symmetry we find independent excitons with distinct polarization selection rules

1300-nm, 1550-nm and 1480-nm wavelength, optically-pumped VECSELs based on wafer-fused InAlGaAs/InPAlGaAs/GaAs gain mirrors with intra-cavity diamond heat-spreaders demonstrate very low thermal impedance of 4 K/W. Maximum CW output of devices with5 groups ...

We report high-power second-harmonic generation of 760 nm laser light from optically-pumped vertical-external-cavity surface-emitting laser based on quantum dot active medium. The laser generates 1.2 W in fundamental transverse mode with fixed linear polar ...

Elyahou Kapon

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Broadband MEMS-Tunable High-Index-Contrast Subwavelength Grating Long-Wavelength VCSEL

Direct observation of new transitions in the absorption spectra of a V-groove quantum wire waveguide

Polarization properties and disorder effects in H-3 photonic crystal cavities incorporating site-controlled, high-symmetry quantum dot arrays

Active Semiconductor Nanophotonics based on Deterministic Quantum Wire and Dot Systems

Experimental evidence for Luttinger liquid behavior in sufficiently long GaAs V-groove quantum wires

Carrier capture into semiconductor quantum dots via quantum wire barriers: Localization and thermionic emission effects

InAsP/InGaAsP Periodic Gain Structure for 1.5µm Vertical Cavity Surface Emitting Laser Applications

Effect of lateral confinement on valence-band mixing and polarization anisotropy in quantum wires

Electrically Pumped Vertical-External-Cavity Surface-Emitting Lasers With Patterned Tunnel Junction for Single Transversal-Mode Emission

Multiexciton dynamics in tailored band-gap quasi-one-dimensional systems

Coupled Photonic-Crystal Cavities and Quantum-Wire Microlasers

Intra-cavity patterning for mode control in 1.3μm coupled VCSEL arrays

Photocurrent spectroscopy of site-controlled pyramidal quantum dots

Physical origins of optical anisotropy in quantum-confined semiconductors: The roles of valence band mixing, transition broadening, and state filling

Band-mixing and coupling in single and double quantum wire structures

Flip-Chip Wafer-Fused OP-VECSELs Emitting 3.65 W at the 1.55-mu m Waveband

Separation of strain and quantum-confinement effects in the optical spectra of quantum wires

The impact of low symmetry on the electronic and optical properties of quantum wires

High-power optically-pumped VECSELs emitting in the 1310-nm and 1550-nm wavebands

High-Power 760 nm VECSEL Based on Quantum Dot Gain Mirror