Frederic Bordas

Second mode transition in microstructured optical fibers : determination of the critical geometrical parameter and study of the matrix refractive index and effects of cladding size

We carried out a numerical study of the second mode transition in finite-sized, microstructured optical fibers (MOFs) for several values of the matrix refractive index. We determined a unique critical geometrical parameter for the second mode cutoff that is valid for all the matrix refractive indices studied. Finite size effects and extrapolated results for infinite structures are described. Using scaling laws, we provide a generalized phase diagram for solid-core MOFs that is valid for all refractive indices, including those of the promising chalcogenide MOFs.

Confinement of band-edge modes in a photonic crystal slab

We study the confinement of low group velocity band-edge modes in a photonic crystal slab. We use a rigorous, three dimensional, finite-difference time-domain method to compute the electromagnetic properties of the modes of the photonic structures. We show that by combining a defect mode approach with the high-density of states associated with bandedge modes, one can design compact, fabrication-tolerant, high-Q photonic microcavities. The electromagnetic confinement properties of these cavities can foster enhanced radiation dynamics and should be well suited for ultralow-threshold microlasers and cavity quantum electrodynamics.

Room temperature low-threshold InAs/InP quantum dot single mode photonic crystal microlasers at 1.5 μm using cavity-confined slow light

We have designed, fabricated, and characterized an InP photonic crystal slab structure that supports a cavity-confined slow-light mode, i.e. a bandgap-confined valence band-edge mode. Three dimensional finite difference in time domain calculations predict that this type of structure can support electromagnetic modes with large quality factors and small mode volumes. Moreover these modes are robust with respect to fabrication imperfections. In this paper, we demonstrate room-temperature laser operation at 1.5 mum of a cavity-confined slow-light mode under pulsed excitation. The gain medium is a single layer of InAs/InP quantum dots. An effective peak pump power threshold of 80 microW is reported.

Microlasers based on effective index confined slow light modes in photonic crystal waveguides.

We present the design, theory and experimental implementation of a low modal volume microlaser based on a line-defect 2D-photonic crystal waveguide. The lateral confinement of low-group velocity modes is controlled by the post-processing of 1 to 3microm wide PMMA strips on top of two dimensional photonic crystal waveguides. Modal volume around 1.3 (lambda/n)(3) can be achieved using this scheme. We use this concept to fabricate microlaser devices from an InP-based heterostructure including InAs(0.65)P(0.35) quantum wells emitting around 1550nm and bonded onto a fused silica wafer. We observe stable, room-temperature laser operation with an effective lasing threshold around 0.5mW.

Lithographic and optical tuning of InGaAsP membrane photonic crystal nanocavities with embedded InAs quantum dots

Hexagonal symmetry InGaAsP membrane type cavities with embedded InAs quantum dots as active emitters were investigated by room temperature photoluminescence experiments at wavelengths near 1.50 μm. Cavities consisting of simple defects of just removing one or seven air holes were studied as well as modified cavities with additional holes decreased in size and shifted in position. The latter include the H0 cavity, in which only two adjacent holes were modified, but none removed. Low-Q cavity modes were observed for the simple cavities while high-Q modes were observed after modification of the surrounding holes. The resonant frequencies were varied over a large range of lithographic parameters both by changing the lattice spacing or the size of the modified holes. More than 15 nm reversible dynamic optical tuning of the resonance modes was observed by changing the applied laser power up to 5 mW. For thermo-optic tuning, this corresponds to a heating of up to 200 °C.

Oxidation of AlInAs for current blocking in a photonic crystal laser

To make an electrically pumped photonic crystal membrane laser is a challenging task. One of the problems is how to avoid short circuiting between the p- and n-doped parts of the laser diode, when the membrane thickness is limited to 200–300nm. We propose to use the oxide of AlInAs to realize a current blocking function. In this way, based on submicron selective area re-growth, we aim for electrically injected photonic crystal lasers with high output power, small threshold currents and low power consumption. Here results are presented on the oxidation of AlInAs. The results show that it is feasible to use the oxide of AlInAs for current blocking in an InP-based membrane photonic crystal laser.

Thermal improvement of InP wire photonic crystal laser on silicon by addition of Diamond Nanoparticles in polymer bonding layer

Diamond Nanoparticles are added to BCB polymer in order to increase the thermal dissipation of InP-based photonic crystal cavity laser bonded on silicon. Optical measurement are performed to evaluate the enhancement of the heat sinking with nanoparticles density.

Room-Temperature InAs/InP Quantum-Dot Photonic Crystal Microlasers Using Cavity-Confined Slow Light

We achieved room temperature laser operation, around 1.5 mum, with a single layer of InAs/InP quantum dots in a photonic crystal structure using confined slow light. The lasing threshold is a few hundred muW.

Control of evanescent wave coupling in hybrid III–V/SOI nanolaser

Silicon photonics, enhanced by III–V semiconductors based optical functions, is one of the most promising technologies to achieve large-scale photonic integration taking advantage of the best of both materials. In this work, we study III–V/SOI hybrid structures that combine photonic crystal nanolasers with photonic wires. This approach is particularly interesting as it enables the achievement of compact devices (footprint as small as 5µm2) with low power activation and ultrafast response.

Hybrid active photonic crystal structures: III-V based slow light waveguides or nanocavities coupled to SOI wires

We report the fabrication of hybrid structures composed of III-V active photonic crystal bonded on top of silicon wires. Laser is obtained from slow light waveguides and from nanocavities made in an InP-based membrane containing quantum wells, the emitted light being coupled evanescently to the SOI wires.