The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray d...The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray diffraction and electron microscopy. A comparison with RE3+: β-PbF2 ceramics prepared by standard ceramic techniques is performed. The Rare Earth cations show a strong nucleating effect for the precipitation of the RE3++: β-PbF2 nanocrystals. The evolution of the unit cell parameters of the REF3: β-PbF2 solid solution results from a combined effect of Pb2+-RE3+ substitution and interstitial F– introduction. In the glass ceramics, RE3+: β-PbF2 nanocrystals are constrained by the glassy matrix when they form with a pressure equivalent to 1.6 GPa. The constrained nanocrystals can return to a relaxed state by chemical dissolution of the embedding glassy matrix, followed by thermal treatments.展开更多
Light-emitting diodes(LEDs)are driving a shift toward energy-efficient illumination.Nonetheless,modifying the emission intensities,colors and directionalities of LEDs in specific ways remains a challenge often tackled...Light-emitting diodes(LEDs)are driving a shift toward energy-efficient illumination.Nonetheless,modifying the emission intensities,colors and directionalities of LEDs in specific ways remains a challenge often tackled by incorporating secondary optical components.Metallic nanostructures supporting plasmonic resonances are an interesting alternative to this approach due to their strong light–matter interaction,which facilitates control over light emission without requiring external secondary optical components.This review discusses new methods that enhance the efficiencies of LEDs using nanostructured metals.This is an emerging field that incorporates physics,materials science,device technology and industry.First,we provide a general overview of state-of-the-art LED lighting,discussing the main characteristics required of both quantum wells and color converters to efficiently generate white light.Then,we discuss the main challenges in this field as well as the potential of metallic nanostructures to circumvent them.We review several of the most relevant demonstrations of LEDs in combination with metallic nanostructures,which have resulted in light-emitting devices with improved performance.We also highlight a few recent studies in applied plasmonics that,although exploratory and eminently fundamental,may lead to new solutions in illumination.展开更多
This paper reviews and discusses recent developments in passively mode-locked vertical external cavity surface emitting lasers （ML-VECSELs） for short pulse generation at 1.55 gin. After comparing ML- VECSELs to othe...This paper reviews and discusses recent developments in passively mode-locked vertical external cavity surface emitting lasers （ML-VECSELs） for short pulse generation at 1.55 gin. After comparing ML- VECSELs to other options for short pulse generation, we reviewed the results of ML-VECSELs operating at telecommunication wavelength and point out the chal- lenges in achieving sub-picosecond operation from a ML- VECSEL at 1.55 gm. We described our recent work in the VECSELs and semiconductor saturable absorber mirrors （SESAMs）, their structure design, optimization and characterization, with the goal of moving the pulse width from picosecond to sub-picosecond.展开更多
The optical properties of germanium can be tailored by combining strain engineering and n-type doping.In this paper,we review the recent progress that has been reported in the study of germanium light emitters for sil...The optical properties of germanium can be tailored by combining strain engineering and n-type doping.In this paper,we review the recent progress that has been reported in the study of germanium light emitters for silicon photonics.We discuss the different approaches that were implemented for strain engineering and the issues associated with n-type doping.We show that compact germanium emitters can be obtained by processing germanium into tensile-strained microdisks.展开更多
Light scattering by a two-dimensional photonic-crystal slab(PCS)can result in marked interference effects associated with Fano resonances.Such devices offer appealing alternatives to distributed Bragg reflectors and f...Light scattering by a two-dimensional photonic-crystal slab(PCS)can result in marked interference effects associated with Fano resonances.Such devices offer appealing alternatives to distributed Bragg reflectors and filters for various applications,such as optical wavelength and polarization filters,reflectors,semiconductor lasers,photodetectors,bio-sensors and non-linear optical components.Suspended PCS also have natural applications in the field of optomechanics,where the mechanical modes of a suspended slab interact via radiation pressure with the optical field of a high-finesse cavity.The reflectivity and transmission properties of a defect-free suspended PCS around normal incidence can be used to couple out-of-plane mechanical modes to an optical field by integrating it in a free-space cavity.Here we demonstrate the successful implementation of a PCS reflector on a high-tensile stress Si_(3)N_(4) nanomembrane.We illustrate the physical process underlying the high reflectivity by measuring the photonic-crystal band diagram.Moreover,we introduce a clear theoretical description of the membrane scattering properties in the presence of optical losses.By embedding the PCS inside a high-finesse cavity,we fully characterize its optical properties.The spectrally,angular-and polarization-resolved measurements demonstrate the wide tunability of the membrane’s reflectivity,from nearly 0 to 99.9470±0.0025%,and show that material absorption is not the main source of optical loss.Moreover,the cavity storage time demonstrated in this work exceeds the mechanical period of low-order mechanical drum modes.This so-called resolved-sideband condition is a prerequisite to achieve quantum control of the mechanical resonator with light.展开更多
文摘The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray diffraction and electron microscopy. A comparison with RE3+: β-PbF2 ceramics prepared by standard ceramic techniques is performed. The Rare Earth cations show a strong nucleating effect for the precipitation of the RE3++: β-PbF2 nanocrystals. The evolution of the unit cell parameters of the REF3: β-PbF2 solid solution results from a combined effect of Pb2+-RE3+ substitution and interstitial F– introduction. In the glass ceramics, RE3+: β-PbF2 nanocrystals are constrained by the glassy matrix when they form with a pressure equivalent to 1.6 GPa. The constrained nanocrystals can return to a relaxed state by chemical dissolution of the embedding glassy matrix, followed by thermal treatments.
基金supported by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek(NWO)through the project LEDMAP of the Technology Foundation STWthrough the Industrial Partnership Program Nanophotonics for Solid State Lighting between Philips and the Foundation for Fundamental Research on Matter FOMsupported by NanoNextNL of the Government of the Netherlands and 130 partners.
文摘Light-emitting diodes(LEDs)are driving a shift toward energy-efficient illumination.Nonetheless,modifying the emission intensities,colors and directionalities of LEDs in specific ways remains a challenge often tackled by incorporating secondary optical components.Metallic nanostructures supporting plasmonic resonances are an interesting alternative to this approach due to their strong light–matter interaction,which facilitates control over light emission without requiring external secondary optical components.This review discusses new methods that enhance the efficiencies of LEDs using nanostructured metals.This is an emerging field that incorporates physics,materials science,device technology and industry.First,we provide a general overview of state-of-the-art LED lighting,discussing the main characteristics required of both quantum wells and color converters to efficiently generate white light.Then,we discuss the main challenges in this field as well as the potential of metallic nanostructures to circumvent them.We review several of the most relevant demonstrations of LEDs in combination with metallic nanostructures,which have resulted in light-emitting devices with improved performance.We also highlight a few recent studies in applied plasmonics that,although exploratory and eminently fundamental,may lead to new solutions in illumination.
文摘This paper reviews and discusses recent developments in passively mode-locked vertical external cavity surface emitting lasers （ML-VECSELs） for short pulse generation at 1.55 gin. After comparing ML- VECSELs to other options for short pulse generation, we reviewed the results of ML-VECSELs operating at telecommunication wavelength and point out the chal- lenges in achieving sub-picosecond operation from a ML- VECSEL at 1.55 gm. We described our recent work in the VECSELs and semiconductor saturable absorber mirrors （SESAMs）, their structure design, optimization and characterization, with the goal of moving the pulse width from picosecond to sub-picosecond.
基金“Triangle de la Physique”under the Gerlas convention and by Agence Nationale de la Recherche under the GRAAL convention(ANR Blanc call 2011 BS0300401)。
文摘The optical properties of germanium can be tailored by combining strain engineering and n-type doping.In this paper,we review the recent progress that has been reported in the study of germanium light emitters for silicon photonics.We discuss the different approaches that were implemented for strain engineering and the issues associated with n-type doping.We show that compact germanium emitters can be obtained by processing germanium into tensile-strained microdisks.
基金funded by the Agence Nationale de la Recherche programs‘ANR-2011-BS04-029 MiNOToRe’and‘ANR-14-CE26-0002 QuNaT’the Marie Curie Initial Training Network‘cQOM’+2 种基金the DIM nano-K Ile-de-France program‘NanoMecAtom’supported by the Marie Sklodowska-Curie Individual Fellowship programsupported by a fellowship'Research in Paris'from the city of Paris.
文摘Light scattering by a two-dimensional photonic-crystal slab(PCS)can result in marked interference effects associated with Fano resonances.Such devices offer appealing alternatives to distributed Bragg reflectors and filters for various applications,such as optical wavelength and polarization filters,reflectors,semiconductor lasers,photodetectors,bio-sensors and non-linear optical components.Suspended PCS also have natural applications in the field of optomechanics,where the mechanical modes of a suspended slab interact via radiation pressure with the optical field of a high-finesse cavity.The reflectivity and transmission properties of a defect-free suspended PCS around normal incidence can be used to couple out-of-plane mechanical modes to an optical field by integrating it in a free-space cavity.Here we demonstrate the successful implementation of a PCS reflector on a high-tensile stress Si_(3)N_(4) nanomembrane.We illustrate the physical process underlying the high reflectivity by measuring the photonic-crystal band diagram.Moreover,we introduce a clear theoretical description of the membrane scattering properties in the presence of optical losses.By embedding the PCS inside a high-finesse cavity,we fully characterize its optical properties.The spectrally,angular-and polarization-resolved measurements demonstrate the wide tunability of the membrane’s reflectivity,from nearly 0 to 99.9470±0.0025%,and show that material absorption is not the main source of optical loss.Moreover,the cavity storage time demonstrated in this work exceeds the mechanical period of low-order mechanical drum modes.This so-called resolved-sideband condition is a prerequisite to achieve quantum control of the mechanical resonator with light.
