L. Cerutti

Single-frequency tunable Sb-based VCSELs emitting at 2.3 /spl mu/m

We present a comparison between two kinds of single-frequency Sb-based semiconductor VCSELs operating at 2.3 /spl mu/m in continuous-wave regime at room temperature. These lasers are studied in view of application to spectroscopy or trace gas detection. Both are based on a molecular beam epitaxy grown half-VCSEL. In the first configuration, a dielectric mirror is deposited on top to form a microcavity, while in the second a concave mirror is used to form an external cavity. The external cavity VCSEL exhibits 5-mW output power, a narrow linewidth (<<20 kHz), and 50-GHz continuous frequency tunability.

Silicon-Based Photonic Integration Beyond the Telecommunication Wavelength Range

In this paper we discuss silicon-based photonic integrated circuit technology for applications beyond the telecommunication wavelength range. Silicon-on-insulator and germanium-on-silicon passive waveguide circuits are described, as well as the integration of III-V semiconductors, IV-VI colloidal nanoparticles and GeSn alloys on these circuits for increasing the functionality. The strong nonlinearity of silicon combined with the low nonlinear absorption in the mid-infrared is exploited to generate picosecond pulse based supercontinuum sources, optical parametric oscillators and wavelength translators connecting the telecommunication wavelength range and the mid-infrared.

Silicon-based heterogeneous photonic integrated circuits for the mid-infrared

In this paper we present our recent work on mid-infrared photonic integrated circuits for spectroscopic sensing applications. We discuss the use of silicon-based photonic integrated circuits for this purpose and detail how a variety of optical functions in the mid-infrared besides passive waveguiding and filtering can be realized, either relying on nonlinear optics or on the integration of other materials such as GaSb-based compound semiconductors, GeSn epitaxy and PbS colloidal nanoparticles.

Silicon-on-insulator spectrometers with integrated GaInAsSb photodiodes for wide-band spectroscopy from 1510 to 2300 nm

We present a silicon-on-insulator (SOI) based spectrometer platform for a wide operational wavelength range. Both planar concave grating (PCG, also known as echelle grating) and arrayed waveguide grating (AWG) spectrometer designs are explored for operation in the short-wave infrared. In addition, a total of four planar concave gratings are designed to cover parts of the wavelength range from 1510 to 2300 nm. These passive wavelength demultiplexers are combined with GaInAsSb photodiodes. These photodiodes are heterogeneously integrated on SOI with benzocyclobutene (DVS-BCB) as an adhesive bonding layer. The uniformity of the photodiode characteristics and high processing yield, indicate a robust fabrication process. We demonstrate good performance of the miniature spectrometers over all operational wavelengths which paves the way to on-chip absorption spectroscopy in this wavelength range.

Continuous-wave operation above room temperature of GaSb-based laser diodes grown on Si

We have investigated specifically designed GaSb-based laser diodes epitaxially grown on a Si substrate. We demonstrate continuous-wave operation of these laser diodes emitting near 2 μm up to 35 °C with several mW/facet output powers, limited by our experimental setup. Our results open the way to direct monolithic III-V/Si integration.

GaSb-Based Laser, Monolithically Grown on Silicon Substrate, Emitting at 1.55

We have investigated the potential of GaSb-based lasers for emission at 1.55 μm and monolithic integration on silicon. We designed an active region based on strained Ga_0.8In_0.2Sb quantum-wells aiming a good carrier confinement. To validate this design, the active region was first used in edge-emitting lasers grown on GaSb substrates. Continuous-wave operation at 1.56 μm has been achieved up to 45°C. The same laser structure grown on Si substrate showed room-temperature operation in pulsed regime at 1.55 μm with a threshold current density of 5 kA/cm².

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We report on a Sb-based type-I laser grown on GaAs substrate, emitting continuous wave at room temperature around 2.2 μm. The device was grown using solid-source molecular beam epitaxy and comprised two GaInAsSb quantum wells embedded in AlGaAsSb barriers. Despite the large lattice mismatch, a good crystalline quality was obtained, and processed devices operated continuous wave up to 50 °C with threshold current densities in the range of 1.5–2.2 kA/cm2. An optical output power of 3.7 mW was obtained at 20 °C.

m at Room Temperature

In this paper we present GaInAsSb photodiodes heterogeneously integrated on SOI by BCB adhesive bonding for operation in the short-wave infrared wavelength region. Photodiodes using evanescent coupling between the silicon waveguide and the III-V structure are presented, showing a room temperature responsivity of 1.4A/W at 2.3 µm. Photodiode structures using a diffraction grating to couple from the silicon waveguide layer to the integrated photodiode are reported, showing a responsivity of 0.4A/W at 2.2 µm.

GaSb-based, 2.2 μm type-I laser fabricated on GaAs substrate operating continuous wave at room temperature

We report on a GaSb-based type-I laser structure grown by molecular beam epitaxy on a (001) silicon substrate. A thin AlSb nucleation layer followed by a 1 μm thick GaSb buffer layer was used to accommodate the very large lattice mismatch existing with the silicon substrate. Processed devices with mesa geometry exhibited laser operation in pulsed mode with a duty cycle up to 10% at room temperature.

Study of evanescently-coupled and grating-assisted GaInAsSb photodiodes integrated on a silicon photonic chip

We demonstrate the occurrence of localized surface plasmon resonances (LSPRs) in periodic arrays of highly doped/un-doped InAsSb/GaSb semiconductor nanostructures, where highly doped InAsSb is degenerated and exhibits a metallic behavior while being lattice-matched onto GaSb. Reflectance spectroscopy allows investigating the impact of the geometrical and physical properties of both InAsSb and GaSb materials on the LSPR. Our results show that these InAsSb/GaSb nanostructures form the building blocks of metal-free, all-semiconductor infrared plasmonic devices.