Nicolas Pauc

Bio: Nicolas Pauc is an academic researcher from University of Grenoble. The author has contributed to research in topics: Germanium & Lasing threshold. The author has an hindex of 21, co-authored 79 publications receiving 1369 citations.

Optically pumped GeSn micro-disks with 16 % Sn lasing at 3.1 um up to 180K

Abstract: Recent demonstrations of optically pumped lasers based on GeSn alloys put forward the prospect of efficient laser sources monolithically integrated on a Si photonic platform. For instance, GeSn layers with 12.5% of Sn were reported to lase at 2.5 um wavelength up to 130 K. In this work, we report a longer emitted wavelength and a significant improvement in lasing temperature. The improvements resulted from the use of higher Sn content GeSn layers of optimized crystalline quality, grown on graded Sn content buffers using Reduced Pressure CVD. The fabricated GeSn micro-disks with 13% and 16% of Sn showed lasing operation at 2.6 um and 3.1 um wavelengths, respectively. For the longest wavelength (i.e 3.1 um), lasing was demonstrated up to 180 K, with a threshold of 377 kW/cm2 at 25 K.

Optically pumped GeSn micro-disks with 16% Sn lasing at 3.1 μm up to 180 K

Abstract: Recent demonstrations of optically pumped lasers based on GeSn alloys put forward the prospect of efficient laser sources monolithically integrated on a Si photonic platform. For instance, GeSn layers with 12.5% of Sn were reported to lase at 2.5 μm wavelength up to 130 K. In this work, we report a longer emitted wavelength and a significant improvement in lasing temperature. The improvements resulted from the use of higher Sn content GeSn layers of optimized crystalline quality, grown on graded Sn content buffers using reduced pressure CVD. The fabricated GeSn micro-disks with 13% and 16% of Sn showed lasing operation at 2.6 μm and 3.1 μm wavelengths, respectively. For the longest wavelength (i.e., 3.1 μm), lasing behavior was demonstrated up to 180 K, with a threshold of 377 kW/cm2 at 25 K.

GeSn Lasers Covering a Wide Wavelength Range Thanks to Uniaxial Tensile Strain

Abstract: Silicon photonics continues to progress tremendously, both in near-infrared datacom/telecoms and in mid-IR optical sensing, despite the fact a monolithically integrated group IV semiconductor laser...

Lasing in strained germanium microbridges.

Abstract: Germanium has long been regarded as a promising laser material for silicon based opto-electronics. It is CMOS-compatible and has a favourable band structure, which can be tuned by strain or alloying with Sn to become direct, as it was found to be required for interband semiconductor lasers. Here, we report lasing in the mid-infrared region (from λ = 3.20 μm up to λ = 3.66 μm) in tensile strained Ge microbridges uniaxially loaded above 5.4% up to 5.9% upon optical pumping, with a differential quantum efficiency close to 100% with a lower bound of 50% and a maximal operating temperature of 100 K. We also demonstrate the effect of a non-equilibrium electron distribution in k-space which reveals the importance of directness for lasing. With these achievements the strained Ge approach is shown to compare well to GeSn, in particular in terms of efficiency. Germanium (based) lasers are a promising route towards a fully CMOS-compatible light source, key to the further development of silicon photonics. Here, the authors realize lasing from strained germanium microbridges up to 100 K, finding a quantum efficiency close to 100%.

GeSn heterostructure micro-disk laser operating at 230 K

Abstract: We demonstrate lasing up to 230 K in a GeSn heterostructure micro-disk cavity. The GeSn 16.0% optically active layer was grown on a step-graded GeSn buffer, limiting the density of misfit dislocations. The lasing wavelengths shifted from 2720 to 2890 nm at 15 K up to 3200 nm at 230 K. Compared to results reported elsewhere, we attribute the increase in maximal lasing temperature to two factors: a stronger optical confinement by a thicker active layer and a better carrier confinement provided by a GeSn 13.8% / GeSn 16.0% / GeSn 13.8% double heterostructure.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Mid-infrared integrated photonics on silicon: a perspective

Abstract: Abstract The emergence of silicon photonics over the past two decades has established silicon as a preferred substrate platform for photonic integration. While most silicon-based photonic components have so far been realized in the near-infrared (near-IR) telecommunication bands, the mid-infrared (mid-IR, 2–20-μm wavelength) band presents a significant growth opportunity for integrated photonics. In this review, we offer our perspective on the burgeoning field of mid-IR integrated photonics on silicon. A comprehensive survey on the state-of-the-art of key photonic devices such as waveguides, light sources, modulators, and detectors is presented. Furthermore, on-chip spectroscopic chemical sensing is quantitatively analyzed as an example of mid-IR photonic system integration based on these basic building blocks, and the constituent component choices are discussed and contrasted in the context of system performance and integration technologies.

Two-dimensional siloxene nanosheets: novel high-performance supercapacitor electrode materials

Abstract: Silicon-based materials have attracted considerable interest for the development of energy storage devices because of their ease of integration with the existing silicon semiconductor technology. Herein, we have prepared siloxene sheets—a two-dimensional (2D) silicon material—and investigated their energy storage properties via fabrication of a symmetric supercapacitor (SSC) device containing 0.5 M tetraethylammonium tetrafluoroborate as the electrolyte. The formation of 2D siloxene sheets functionalized with oxygen, hydrogen, and hydroxyl groups was confirmed through X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and laser Raman mapping analyses. Cyclic voltammetric studies of the siloxene SSC device revealed the presence of pseudocapacitance in the siloxene sheets that arose from an intercalation/deintercalation phenomenon. The galvanostatic charge–discharge profiles of the device displayed sloped symmetric triangular curves with a maximum specific capacitance of 2.18 mF cm−2, high energy density of 9.82 mJ cm−2, good rate capability, and excellent cycling stability of 98% capacitance retention after 10 000 cycles. The siloxene SSC device delivered a maximum power density of 272.5 mW cm−2, which is higher than those of other silicon- and carbon-based SSCs, highlighting their potential for application in energy storage.

Filter-Free Image Sensor Pixels Comprising Silicon Nanowires with Selective Color Absorption

Abstract: The organic dye filters of conventional color image sensors achieve the red/green/blue response needed for color imaging, but have disadvantages related to durability, low absorption coefficient, and fabrication complexity. Here, we report a new paradigm for color imaging based on all-silicon nanowire devices and no filters. We fabricate pixels consisting of vertical silicon nanowires with integrated photodetectors, demonstrate that their spectral sensitivities are governed by nanowire radius, and perform color imaging. Our approach is conceptually different from filter-based methods, as absorbed light is converted to photocurrent, ultimately presenting the opportunity for very high photon efficiency.