Publications by Romuald Houdré

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By imaging the angular spectrum of optical modes confined within subwavelength volumes, we investigate the impact of metallic and dielectric surrounding layers on the optical emission properties of planar silicon photonic crystal cavity. By scanning a mirror close to the surface of the cavity, we experimentally show an enhancement of the cavity quality factor Q based on the annihilation of the amplitude of the cavity leaky modes. The experimental observations are in agreement with a model based on transfer

It is demonstrated that during the first few picoseconds after resonant femtosecond excitation the secondary radiation from a strongly coupled semiconductor microcavity containing one quantum well is dominated by Rayleigh scattered light. At early times after excitation (10 ps) the lower polariton branch provides the most intense emission which is due to incoherent luminescence.

Nematic liquid crystals are infiltrated into InP-based planar photonic crystals. Optical measurements as a function of temperature and polarization are used to study the average director field configuration in the nanometer-size holes: a planar equilibrium ...

The use of photonic crystals (PCs) for realistic light emitting diodes (LEDs) is discussed, given the constraints of planar semiconductor technology. A viable route for the fabrication of high-efficiency high-brightness electrically injected LEDs is presented. The starting point is a top-emitting microcavity using a single Alox Bragg mirror. The active area is surrounded by two-dimensional PCs, namely arrays of air rods etched through the top layers; injection of the electrons is achieved through the crysta

This work addresses feature size effects (the lag-effect and roughness development) in chemically assisted ion beam etching (CAIBE) etching of InP-based photonic crystals. Photonic crystal fields with varying hole size and periods were etched with differen ...

Coupling into the Bloch modes of a two-dimensional photonic crystal (PhC) field is investigated by Fourier optics. The PhC was designed to operate in the second band above the air-light line, close to the autocollimation regime for TE polarization. The sam ...

We present the local polymer infiltration of planar photonic crystal cavities via a maskless laser-writing technique. After the infiltration of the air holes with a UV-curable monomer a focused laser is used to locally polymerize the monomer in selected ho ...

We report on the optical response of a semiconductor microcavity featuring a strong exciton-photon coupling. The weak excitation regime is investigated experimentally by means of time-resolved transmission and four-wave mixing experiments. The influence of electronic disorder on the coherent exciton-photon dynamics is discussed in terms of tl-ie solutions of the Maxwell-Bloch equations. The high excitation regime is investigated by using transient sub-picosecond pump-probe experiments. Optical amplification

Although optical technology provides the best solution for the transmission of information, all-optical devices must satisfy several qualitative criteria to be used as logic elements. In particular, cascadability is difficult to obtain in optical systems, ...

We report on the achievement of freestanding GaN photonic crystal L7 nanocavities with embedded InGaN/GaN quantum wells grown by metal organic vapor phase epitaxy on Si (111). GaN was patterned by e-beam lithography, using a SiO2 layer as a hard mask, and ...

We combine photonic crystal and quantum cascade band engineering to create an in-plane laser at terahertz frequency. We demonstrate that such photonic crystal lasers strongly improve the performances of terahertz quantum cascade material in terms of thresh ...

We demonstrate edge-emitting lasers based on self-assembled InAs quantum dots (QDs) on GaAs substrates. The InAs QDs are embedded in an InGaAs quantum well (QW) to red-shift the lasing transition. The lasers emit at lambda=1.2 mum with threshold current densities approximate to100 A/cm(2). Maximum modal gains on the order of 5 cm(-1) are deduced for a single QD sheet.

Disclosed is a semiconductor laser that is constituted by at least one active layer sandwiched between two confinement layers with P and N type doping to constitute a PN junction. In at least one of the confinement layers and/or the active layer, holes are designed on each side of the cavity so as to form structures of photonic bandgap material along the lateral walls of the cavity and the ends of the cavity.

The coherent dynamics of cavity-polaritons are investigated using the four-wave-mixing technique. A series of experiments on four samples operating in both the weak and strong coupling regimes were performed to study the influence of strong coupling on the interaction of cavity-polaritons with other cavity-polaritons, free carriers and acoustic phonons. Due to Rabi splitting a larger number of free carriers are created in the strong coupling sample compared with the weak coupling sample. This has a signific

We report a cathodoluminescence (CL) study at helium temperature of oval defects on quantum well (QW) structures grown by molecular beam epitaxy (MBE). We collected the luminescence emitted both from the facet shaped defect and from the defect free growth region. By comparing the experimental CL peak position with the numerically estimated values, we determined the Al concentration and the thicknesses of the layers in the defect area.

We report femtosecond pump and probe experiments in a semiconductor microcavity containing quantum wells. At high pump fields, the exciton-polariton Rabi doublet changes into a triplet structure. The triplet splitting increases as the square root of the input intensity. The transmitted probe intensity is modulated with the corresponding frequency Versus pump-probe delay. The experimental results are discussed in terms of Mollow spectra of a saturated transition of a two-level system.

We report the design and optical characterization of fully suspended wire waveguides and photonic crystal (PhC) membranes fabricated on a gallium nitride layer grown on silicon substrate operating at 1.5 mu m. W1-type PhC waveguides are coupled with suspen ...

The optical tuning of InP-based planar photonic crystals (PhCs) infiltrated with a photo-responsive liquid crystal system is presented. Photo-induced phase transitions of a liquid crystal blend doped with azobenzene molecules are used to tune the optical r ...

Regular periodic structures with large refractive index contrast are often called photonic crystals and may exhibit photonic bandgap behaviour. Planar waveguide 2D and 1D periodic microstructures exhibiting photonic bandgap behaviour are likely to be useful in realising the devices and connecting structures required for compact forms of integrated optical circuit.

We present a phase-shifting holography method in k space that allows us to investigate the phase and amplitude of optical Bloch waves. The method is based on a Fourier space imaging technique combined with a Mach-Zehnder interferometer. Using a W3 photonic ...

Romuald Houdré

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Inhibition of the Emission of Electromagnetic Modes of Photonic Crystal Cavities with a Top Mirror

Resonant Rayleigh scattering versus incoherent luminescence in semiconductor microcavities

Planar photonic crystals infiltrated with liquid crystals: optical characterization of molecule orientation

High extraction efficiency, laterally injected, light emitting diodes combining microcavities and photonic crystals

Feature size effects in chemically assisted ion beam etching of InP-based photonic crystals

Bloch mode excitation in two-dimensional photonic crystals imaged by Fourier optics

Local infiltration of planar photonic crystals with UV-curable polymers

Exciton-photon dynamics in weakly and strongly excited semiconductor microcavities

All-optical polariton transistor

High quality factor two dimensional GaN photonic crystal cavity membranes grown on silicon substrate

Terahertz photonic crystal quantum cascade lasers

Long-wavelength edge-emitting lasers on gallium arsenide using InAs quantum dots embedded in InGaAs

Semiconductor laser having a photonic bandgap material

Dephasing of strongly coupled exciton-photon systems

Cathodoluminescence Study of Oval Defects on Qw Structures

Strongly driven semiconductor microcavities: From the polariton doublet to an AC Stark triplet

Near-infrared characterization of gallium nitride photonic-crystal waveguides and cavities

Optical tuning of planar photonic crystals infiltrated with organic molecules

Waveguide photonic crystals and microstructures

Phase-sensitive Fourier space imaging of optical Bloch modes