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We report quantum cascade lasers emitting at a wavelength near 3.3μm up to a temperature of 400K in pulsed mode. A fine tuning of the InAs∕AlSb active region design allowed to maintain efficient electron injection and to reduce thermal backfilling at high temperatures. The threshold current density is 3kA∕cm2 at 300K with characteristic temperature T0 of 175K. The lasers emitted up to 1W peak power in a single lateral mode at room temperature.

International audience; Quantum cascade lasers emitting below 3 μm are demonstrated. The lasers based on the InAs/AlSb material system emit at 2.95-2.97 μm in pulsed mode with threshold current densities near 3 kA/cm2 at 84 K and operate up to room temperature. No degradation has been observed in laser performances compared with InAs/AlSb quantum cascade lasers emitting at 3.14-3.35 μm. The obtained results show no influence of the L valley in InAs on operation of these short wavelength quantum cascade lasers

We demonstrate the external control of the intersubband polariton coupling in a GaAs/AlGaAs microcavity, utilizing the electronic tunneling between energetically aligned ground states of an asymmetric coupled quantum well structure. We suggest this scheme as the basic element for the ultrafast manipulation of the polariton ground state. Preliminary results of intersubband polaritons in InAs‐AlSb microcavities, towards the realization of the ultra‐strong coupling regime, are also reported.

The optical response of the intersubband excitation of multiple InAs/AlSb quantum wells embedded in a planar semiconductor microcavity has been studied through angle-dependent reflectance measurements. Using a resonator based on total internal reflection, a strong coupling is demonstrated between the intersubband optical transition and the cavity photon, with the attendant formation of intersubband polaritons. A giant vacuum-Rabi splitting 2 Ω R was observed both at liquid helium temperatures ( 2 Ω R = 33 meV ) as well as at 300 K ( 2 Ω R = 32 meV ), for a transition energy ω 12 = 123 meV . The observed ratio Ω r ω 12 is a record high value (14%) for any strongly-coupled systems, and demonstrates the huge potential of this material for the achievement of the ultra-strong coupling regime predicted theoretically.

We report on the growth, fabrication, experimental study and application in an absorption gas setup of distributed feed-back antimonide diode lasers with buried grating. First, half laser structures were grown by molecular beam epitaxy on GaSb substrates and stopped at the top of the waveguide. A second order Bragg grating was then defined by interferometric lithography on the top of the structure and dry etched by Reactive Ion Etching. The grating was, afterwards, buried thanks to an epitaxial regrowth of the top cladding layer. Finally, the wafer was processed using standard photolithography and wet etched into 10 µm-wide laser ridges. A single frequency laser emission around 2.3 µm was recorded, a maximum output power of 25 mW and a total continuous tuning range reaching 4.2 nm at fixed temperature. A device has been used to detect methane gas and shows strong potential for gas spectroscopy. This process was also replicated for a target of 3 µm laser emission. These devices showed an output power of 2.5 mW and a SMSR of at least 23 dB, with a 2.5 nm continuous tuning range at fixed temperature.

International audience; We report on the modeling, growth, processing, characterization and integration in a gas detection setup of side wall corrugated distributed feed-back antimonide diode lasers emitting at 2.28 and 2.67 μm. The laser structures were grown by molecular beam epitaxy on GaSb substrate. Ridge lasers were fabricated from the grown wafers according to the following process: a second order Bragg grating was defined on the sides of the ridges by interferometric lithography, optical lithography and etched in a Cl-based inductively coupled plasma reactor. The devices exhibit a power reaching 40 mW, a side mode suppression ratio better than 28 dB and a tuning range of 3 nm at room temperature. One of these devices was successfully integrated in a tunable diode laser absorption spectroscopy setup, thus demonstrating that they are suitable for gas analysis.

The electroluminescence signal emitted from operating InP-based heterojunction bipolar transistors (HBT) is analyzed, giving clear evidence of ballistic electron transport through the base. The luminescence signal is studied as a function of base thickness, providing direct access to the ballistic electron mean free path. This continuous wave technique proves to be very efficient to measure ballistic electron scattering rates: 30 fs at 77 K and 19 fs at 300 K for a base Be doped to 1019 cm−3.Quasiballistic transport range is found to be comparable to base width accessible by state of the art device technology, demonstrating its importance for ultrafast HBT operation.

The quantum efficiency of an electroluminescent intersubband emitter based on $\mathrm{In}\mathrm{As}∕\mathrm{Al}\mathrm{Sb}$ has been measured as a function of the magnetic field up to $20\phantom{\rule{0.3em}{0ex}}\mathrm{T}$. Two series of oscillations periodic in $1∕B$ are observed, corresponding to the elastic and inelastic scattering of electrons of the upper state of the radiative transitions. Experimental results are accurately reproduced by a calculation of the excited-state lifetime as a function of the applied magnetic field. The interpretation of these data gives an exact measure of the relative weight of the scattering mechanisms and allows the extraction of material parameters such as the energy-dependent electron effective mass and the optical phonon energy.

In this paper InAs/AlSb quantum cascade structures operating at room temperature with peak emission wavelength down to 2.55 /spl mu/m, the shortest emission wavelength of intersubband transitions reported to date. No degradation in structure performances was observed with the emission wavelength decreasing from 4.5 to 2.55 /spl mu/m. The obtained results prove the great potential of the InAs/AlSb system for the development of short wavelength QCLs.

New concepts for efficient light absorption in nanoscale metal-semiconductor-metal photodetectors are analyzed from both theoretical and experimental point of view. They are based on sub-wavelength metallic gratings which allows light confinement in tiny volumes (< 100 nm) close to electrodes (< 100 nm). Two photodetector structures are proposed: (i) a resonant-cavity-enhanced subwavelength metal-semiconductor-metal photodetector, and (ii) a nanoscale metal-semiconductor grating photodetector. External quantum efficiency as high as 9 % has been obtained in 40 x 100 nm2 cross-section GaAs wires, limited by fabrication technology. These results show promising features for highly efficient and ultrafast photodetectors.

Intersubband electroluminescence from InAs/AlSb quantum cascade structures has been obtained between 2.8 and 3.2 mum up to room temperature with full widths at half maximum of the emission spectra less than 30 meV at 90 K

International audience; The room temperature operation of InAs/AlSb quantum cascade lasers is reported. The structure, grown by molecular beam epitaxy on an InAs substrate, is based on a vertical transition design and a low loss n+-InAs plasmon enhanced waveguide. The lasers emitting near 4.5 μm operate in pulse regime up to 300 K. The threshold current density of 3.18-mm-long lasers is 1.5 kA/cm2 at 83 K and 9 kA/cm2 at 300 K.

International audience; A nanoscale metal-semiconductor grating is proposed for efficient and ultrafast photodetection. Theoretical and experimental results of efficient absorption in nanoscopic semiconductor wires are presented. The strong confinement of light in subwavelength metal-semiconductor gratings is achieved by Fabry-Pérot resonances involving vertical transverse magnetic surface-plasmon waves and transverse electric guided waves. Photodetectors have been fabricated with 40×100 nm cross sections of Ag and GaAs wires. The reflectivity and photocurrent mesurements are in good agreement with theoretical estimates.

Low‐temperature (1.8 K) photoluminescence spectra of a Ga0.52In0.48P–(Al0.58Ga0.42)0.52In0.48P multiple quantum well have been measured as a function of hydrostatic pressure from 0 to 5.0 GPa. The extrapolation to zero pressure of the energy of the indirect k‐and‐real‐space barrier X to well Γ transition allows the direct determination of the valence band offset for this heterojunction system. A value of ΔEv=(0.35±0.05)ΔEg is found, in good agreement with values previously determined from the theoretical modeling of quantum well transition energies.

International audience; Noncontact mode electrostatic force microscopy was employed to investigate cleaved sections of a GaSb-based quantum cascade laser structure. The technique enabled us to determine the surface potential distribution, at equilibrium and under applied external field, and to locate precisely the zone which is at the origin of failure in laser characteristics when a breakdown voltage is applied to the device

In this paper we propose and demonstrate a novel approach for improving high frequency performance of InP-based HBTs. A new structure, the Metal Heterojunction Bipolar Transistor (MHBT) where the semiconductor is replaced by a metal in the collector layer is described. This structure not only ensures high dynamic characteristics, but also provides satisfactory static behavior. MHBT demonstrators manufactured for this study show at J/sub c/=30 KA/cm/sup 2/ a current gain cutoff frequency, f/sub T/, of 51 GHz and a maximum oscillation frequency, f/sub max/ of 160 GHz despite their thick base (150 nm) and collector (450 nm) layers. The f/sub max/ value is, for this non-optimized structure, in the range of the best values reported for InP-HBTs. In addition the effective delay time (R/sub c/C/sub BC/)/sub eff/=f/sub T//(8/spl pi/f/sub max//sup 2/) is as small as 78 fs.

In this paper the intrinsic dynamic behavior of the metal heterojunction bipolar transistor (MHBT) is studied. Non-equilibrium electron transport in the base is characterized by electroluminescence. Clear evidence of ballistic transport in MHBT's is shown even at room temperature. The ballistic length is found equal to 17.8 nm in p-InGaAs (N/sub A/=10/sup 19/ cm/sup -3/). Based on these experimental results, an analytical model is developed in order to predict the transit times in both the base and the base-collector space charge layer of the MHBTs.

The inelastic scattering rates of electrically injected minority hot electrons measured using a continuous-wave spatially resolved electroluminescence spectroscopy are reported. To our knowledge, this constitutes direct experimental determination of this parameter related to the individual inelastic interactions. The evolution of the electron relaxation rate with increasing majority hole density is explored. Remarkably, an attenuation of the scattering rate is measured for p-doping levels higher than $2\ifmmode\times\else\texttimes\fi{}{10}^{19} {\mathrm{cm}}^{\ensuremath{-}3}.$ Additionally, the measured hot-electron energy distributions further indicate that the relaxation mechanisms are dominated by LO phonon-plasmons coupled modes in the range ${10}^{18}$ to ${10}^{19} {\mathrm{cm}}^{\ensuremath{-}3}$ hole density. Finally, the temperature dependence of inelastic scattering rate is also measured to learn on the potential implication of ballistic transport in RT operating hot-electron devices.

International audience; In transmission metallic gratings, quasi-total transmission of light is achieved by two different mechanisms, which are the excitation of horizontal and vertical surface-plasmon resonances. Both resonances are represented on complex photonic band structures for a wide range of grating thicknesses. The evolution of the electromagnetic field intensity provides a physical understanding of the behaviour of dispersion curves and of lifetime discontinuities in Wood-Rayleigh anomalies in particular. Both radiative and non-radiative processes are distinguished in the resonances' width, giving limits for the use of metallic gratings in photonic devices.

We report on the growth, fabrication, and experimental study of distributed feed-back antimonide diode lasers with buried grating. A second order index-coupled grating was defined by interferometric lithography on the top of the laser waveguide and dry etched by reactive ion etching. The grating was then buried thanks to an overgrowth of the top cladding layer using molecular beam epitaxy. The wafer was then processed using standard photolithography and wet etching into 15 μm-wide laser ridges. Single frequency laser emission at a wavelength of 2.2 μm was measured with a side mode suppression ratio of 34 dB, a maximum output power of 30 mW, and a total continuous tuning range of 6.5 nm.

International audience; We demonstrate quantum cascade lasers in the InAs/AlSb material system emitting at wavelengths of λ = 19 μm and λ = 21 μm. The maximum operating temperatures are 291 K and 250 K, and the threshold current densities at 78 K are as low as 0.6 kA/cm2 and 1.3 kA/cm2 for the lasers emitting at λ = 19 μm and λ = 21 μm, respectively. These values represent the best performance to date for quantum cascade lasers operating above λ = 16 μm. Although the devices employ metal-metal waveguide geometries, the diffraction effects which typically hinder the output beam of THz devices are not observed.We thank Nathalie Isac for help with the wafer-bonding process. We acknowledge financial support from the French National Research Agency (No. ANR-11-NANO-020 “DELTA”) and by the Collaborative Action (No. 8748RA12) between the CEA and the University Paris Sud. The device fabrication has been performed at the nano-center CTU-IEF-Minerve—part of the French RENATECH network—which was partially funded by the Conseil Général de l'Essonne

Complex photonic band structures (CPBS) of transmission metallic gratings with rectangular slits are shown to exhibit strong discontinuities that are not evidenced in the usual energetic band structures. These discontinuities are located on Wood's anomalies and reveal unambiguously two different types of resonances, which are identified as horizontal and vertical surface-plasmon resonances. Spectral position and width of peaks in the transmission spectrum can be directly extracted from CPBS for both kinds of resonances., 4 pages, 4 figures, REVTeX version 3

We have observed a bistability of low‐temperature photoluminescence in a n‐i‐n type II GaAs/AlGaAs/AlAs quantum heterostructure. The integrated luminescence intensity ratio between the two states may reach 50. In as‐grown samples, the bistability range lies between 40 and 250 W/cm2. These threshold values may be reduced on mesa‐type samples, using an external load resistor. Spectral analysis and electrical measurements indicate that the two states correspond to hole accumulation in different layers of the structure. The transition occurs with the alignment of electronic Γ and X states due to optical pumping.

We propose an experimental method of near field optical imaging by scanning probe microscopy in which the probe itself serves as an infrared photodetector. The method providing a submicron spatial resolution is based on detection of a shift of the probe resonance related to its heating by absorbed IR radiation. The method does not require an apertured probe and can be realized with a conventional silicon probe used in atomic force microscopy. The method has been employed for visualization of infrared emission from a half-disk semiconductor whispering gallery mode laser.

Room temperature, tunable, external-cavity short-wavelength InAs/AlSb quantum cascade laser (QCL) is reported. Wavelength tuning of 85 nm for the spectral range between 3190 nm and 3275 nm has been achieved by rotating the diffraction grating forming the external cavity. To suppress lasing inside the QCL cavity, its ridge was tilted by 7° at the external cavity end. The optimal tilting angle of the laser ridge was chosen by careful consideration of the return losses of the TM-polarized waveguide mode from the diffraction grating in a quasi-Littrow configuration and the Fabry-Perot feedback from the tilted laser facet. No antireflection coating was used.

Zone-center-zone-boundary ($\ensuremath{\Gamma}\ensuremath{-}X$) intervalley transfer mechanisms in AlAs/GaAs heterostructures are deduced in an unambiguous way from transport and electroluminescence studies of single-AlAs-barrier diodes. We demonstrate that the tunneling is strongly sequential and depends on the nature of the $X$ state involved. For ${X}_{z}$ the transfer is mainly elastic, whereas momentum conserving phonon assistance is dominant for ${X}_{\mathrm{xy}}$. Quantitative values for the scattering rates for each transfer mechanism are obtained. The conduction-band offset from the $\ensuremath{\Gamma}$ minimum in GaAs to the $X$ minimum in AlAs is shown to be only 120\ifmmode\pm\else\textpm\fi{}6 meV.

We report the observation by photoluminescence (PL) spectroscopy of cross‐barrier recombination between spatially separated two‐dimensional electron and hole gases confined respectively in the quantum well (QW) and collector accumulation layer of a GaAs/AlGaAs double‐barrier resonant tunneling structure. At the onset of the n=3(E3) resonance in the current–voltage characteristic, the energy of the cross‐barrier transition Ecr is found to coincide with that of the PL peak arising from recombination of electrons from the E3 confined level in the QW with n=1 confined hole states (E3lh recombination). Similarly, at the onset of the E4 resonance, Ecr≊E4lh. We show that this behavior arises as a consequence of the symmetrical potential distribution within the structure at the onsets of the resonances.

We have identified the Γ-X and X-Γ intervalley tunneling mechanisms in GaAs/AlAs/GaAs single barrier p-i-n structures by employing electroluminescence and transfort techniques. We show that the Γ-X-Γ tunneling process proceeds by either elastic transfer into Xz states or momentum conserving phonon assisted transfer involving Xxy states. The tunneling out occurs. The Γ-Γ-Γ component of the tunnel current is observed to be more than two orders of magnitude weaker than transfer via X states.

We present experimental studies of photocreated carrier population in type II heterostructures. The main effects are related to charge separation and band filling : Blue shift and broadening of the luminescence line, transition from indirect recombination to pseudo-direct, and then to direct-type I recombination. They may lead to more complex non-linear effects such as bistability. These effects can be accounted for by theory in the framework of the Envelope-Function Approximation, by self consistent treatment of the Poisson and Schroedinger equations.

In “type II” heterostructures, potential profiles of conduction and valence bands are such that electrons are separated from holes, in real space. As a consequence, illumination induces charge separation and thus internal electric fields, which, in turn, modify the properties of the structure. On the other hand, it is now well established that such type II heterostructures may be obtained from various associations of GaAs, GaAlAs, and AlAs [1,2,3]. This happens as far as X-point conduction states are concerned. As a consequence, new tools for “band gap engineering” are available in this well controlled family of material; for instance, an indirect-to-direct transition has been observed in a GaAs/AlAs superlattice under external electric field [4], with consequences on the photoluminescence intensity. As a further example, in a more sophisticated and asymmetric structure, spatial separation of charges has been demonstrated to create an internal electric field with subsequent action on the photoluminescence emission energy of the structure [5]. More recently, Zrenner and coworkers [6] have observed an intrinsic optical bistability under external electric field, thought to be due to hot carriers.

Quantum cascade lasers (QCLs) emitting at wavelengths as short as 2.63–2.65 μm are demonstrated. The InAs/AlSb QCL design was optimized to weaken carrier leakage into the L-valley by reducing coupling between the active InAs quantum wells. The lasers with HR-coated facets operated up to 175 K.

We study a Quantum Hot Electron Transistor, an original transistor made of InAs/AlSb heterostructures with high speed intrinsic transport. It is a unipolar vertical transport device, based on the concept of hot electron transistor. Devices using different heterostructure designs have been grown, processed and characterized. Both resonant and parasitic transport of electrons is studied by mean of the static output characteristics of the transistors. We demonstrated that a key parameter is the design and thickness of the collector barrier. For 15nm-thin barriers, we obtained static current gain of 5 associated to a base transit time of 140 fs.

Quantum cascade lasers emitting at wavelengths as short as 2.75μm at 80K and 2.97μm near room temperature are demonstrated. Despite the small band gap of InAs, the laser performances are not affected by interband absorption. No effect of the L valley in InAs on quantum cascade laser performances is observed at 80K in these devices.

Quantum cascade lasers emitting at wavelengths as short as 3.1–3.3μm are reported. Such high intersubband emission energies (up to 400meV) have been obtained thanks to the high conduction band offset of the InAs∕AlSb material system. The structures, grown by molecular beam epitaxy on InAs substrates, are based on the bound-to-continuum design and use a low loss plasmon enhanced waveguide consisting of n+-InAs cladding layers with InAs∕AlSb superlattice spacers surrounding the active zone. The lasers exhibit threshold current densities close to 3kA∕cm2 at 83K and operate in pulsed mode up to 240K.

InAs/AlSb quantum cascade lasers emitting at 3.5–3.65 µm are demonstrated. The lasers employ a plasmon enhanced waveguide consisting of heavily doped n-InAs cladding layers and low doped InAs spacers. The maximum operation temperature is 200 and 140 K for lasers emitting near 3.65 and 3.5 µm, respectively. The present lasers' performances are limited by interband absorption in narrow gap InAs spacers.

International audience; The InAs/AlSb material system is a promising candidate for the development of short wavelength quantum cascade lasers because of the large conduction band offset of 2.1 eV. In this letter, we present a study of room temperature electroluminescence of InAs/AlSb quantum cascade structures as a function of the emission wavelength. Intersubband emission with a transition energy of 500 meV (λ=2.5 μm) has been obtained.

Quantum cascade lasers based on the InAs/AlSb material system have been realised. The optical confinement is obtained using a plasmon waveguide with n+-InAs cladding layers. In pulse mode the lasers emit close to 6.7 µm with a threshold current density of 5 kA/cm2 at 90K. The maximum operating temperature is 220K.

A study of the effects of the injected current and the thermal resistance on the tunability of antimonide-based diode lasers is presented. The studied diode lasers, emitting at around 2.3 µm, are dedicated to gas detection in the atmosphere, based on tunable-diode-laser absorption spectroscopy (TDLAS). This very useful technique requires, from the lasers, an emitted tunable wavelength able to cross a gas absorption line to detect the absorbed light. Typically a tuning rate of a few GHz/mA is sufficient to perform gas detection at atmospheric pressure (Vicet et al., 2002). It is then important to know and understand the tuning properties of the devices to achieve gas detection. They are very sensitive to thermal effects which are involved in all tuning processes. The lasers studied are shown to be well adapted to gas detection, paradoxically because of their large thermal resistance Rth which increases Joule heating, and mainly affects their tunability.

We report on experimental observation of impact ionization in InAlAs/InP heterojunction field effect transistors (HFET) with an InP channel. The I g(V gs) V ds static characteristics and electroluminescence intensity are compared, exhibiting similar evolutions with bias conditions. These observations indicate that minority carriers (holes) are generated in the structure, through an impact ionization process. This process, unusual in InP channel FETs, is attributed to the staggered InAlAs/InP interface.

A new low-bandgap III-V compound grown on GaAs (GaAsSbN) has been investigated. Strained quantum wells were realised by molecular beam epitaxy with a nitrogen plasma source. The influence of Sb content on the level of nitrogen incorporation has been examined and no strong dependence was found. This material offers an interesting alternative to InGaAsN for developing 1.3 and 1.55 /spl mu/m laser sources on GaAs substrates: a GaAs/sub 0.729/Sb/sub 0.259/N/sub 0.012//GaAs quantum well has exhibited a room-temperature photoluminescence peak wavelength as long as 1.52 /spl mu/m. This emission is shifted to 1.3 /spl mu/m after post-growth annealing.

We discuss the necessary conditions to obtain a photovoltaic effect in type-II structures. On this basis we design a type-II GaAs/GaAlAs/AlAs asymmetric unit cell, which is cascadable. In a n-i-n diode containing this unit cell, we observe a photovoltage, with spectrally dependent sign. The photovoltage excitation spectrum is compared with photoluminescence and excitation of luminescence spectra. This effect is associated with spatial separation of photocreated electrons and holes in spectrally selected regions of the structure.

Sb-based materials rely on the GaSb, InAs, AlSb, InSb binary compounds and their quaternary or pentanary alloys (AlGaAsSb, GaInAsSb, AlGaInAsSb,.. ). This technology exhibits several distinctive properties as compared to other semiconductors: type-I to type-III band alignments, giant band offsets, low effective masses of electrons and holes, direct bandgaps between 0.15 and 1.7 eV. Conventional laser diodes (LDs) rely essentially on GaInAsSb type-I quantum wells (QWs) confined by AlGa(In)AsSb barrier layers. Low threshold currents and high T0 have been demonstrated between 1.5 and 3.4 µm. The AlGaInAsSb pentanary barrier is needed to extend the wavelength beyond 3 µm while keeping a type-I band alignment [3] even though it makes the epitaxial growth complex. Single mode operation has been achieved with both DFB lasers and VCSELs using the same active zone. At longer wavelength, interband cascade lasers (ICLs) based on GaInSb/InAs type-II p-n junctions stacked in series exhibit room temperature cw emission between 3.5 and 5 µm, including single mode operation of DFB lasers. At still longer wavelength InAs/AlSb quantum cascade lasers (QCLs) benefit from the low InAs effective mass and giant conduction band offset. High performance have been demonstrated all the way from 2.6 µm up to 25 µm, particularly at long wavelength which is an asset of this technology. The evolution toward smart, integrated, sensors requires integrating III-V optoelectronic devices with Si-based platforms. The epitaxial growth of III-V compounds on Si has thus been the focus of renewed attention for about a decade now. We have shown that the Si substrate preparation and the III-Sb nucleation on Si are crucial steps. This allowed us demonstrating a variety of epitaxially integrated optoelectronic devices such as laser diodes, photodetectors and the first ever QCL grown on Si. In this presentation we review the recent results obtained on the integration of antimonide-based QCLs epitaxially grown on Si substrates. We will show that this technology is very attractive for future III-V on Si integration, and we will discuss future integration schemes.

Emission of longitudinal optical phonons between the upper and the lower polariton branches has been observed in an intersubband electroluminescent device, operating in the strong coupling regime.

International audience

In last two decades QCL technology has proved itself as the most promising platform for many industrial and emerging applications such as gas sensing, environmental monitoring, LIDARs, free-space optical communications and many others. The investigations in topology resulted in the first QCL device that is robust to the structural defects [1] . At the same time, despite many valuable developments, there are still some unrevealed questions related to the carrier dynamics. One of them is the experimental investigations of the QCL turn-on delay time, which is a key parameter in many QCL-based technologies.

International audience; We theoretically and experimentally study the THz electromagnetic properties of an undoped-InAs slab whose permittivity is optically modified by a photo-generation process. The modulation of the permittivity is calculated by solving the ambipolar rate equation for the free carriers. Experiment results demonstrate that InAs is a promising semiconductor to manufacture fast and efficiently on-chip THz components. We show a high modulation of the THz transmission up to 100% from 0.75 to 1.1THz at very low pump fluence in the continuous wave regime. We also demonstrate a high-speed transmission modulation rate up to the MHz range with a modulated pump.

There is currently much activity toward the integration of mid-infrared semiconductor lasers on Si substrates for developing a variety of smart, compact, sensors based on Si-photonics integrated circuits. We review this rapidly-evolving research field, focusing on the epitaxial integration of antimonide lasers, the only technology covering the whole mid-to-far-infrared spectral range. We explain how a dedicated molecular-beam epitaxy strategy allows for achieving high-performance GaSb-based diode lasers, InAs/AlSb quantum cascade lasers, and InAs/GaInSb interband cascade lasers by direct growth on on-axis (001)Si substrates, whereas GaAs-on-Si or GaSb-on-Si layers grown by metal-organic vapor phase epitaxy in large capability epitaxy tools are suitable templates for antimonide laser overgrowth. We also show that etching the facets of antimonide lasers grown on Si is a viable approach in view of photonic integrated circuits. Remarkably, this review shows that while diode lasers are sensitive to residual crystal defects, the quantum cascade and interband cascade lasers grown on Si exhibit performances comparable to those of similar devices grown on their native substrates, due to their particular band structures and radiative recombination channels. Long device lifetimes have been extrapolated for interband cascade lasers. Finally, routes to be further explored are also presented.

L’habilitation à diriger des recherches présentée ici se structure autour de deux thématiques principales intitulées Lasers et métrologie optique et Composants et systèmes THz. Les recherches menées sur la thématique Lasers et métrologiese sont focalisés sur la réalisation et l’étude de lasers cohérents temporellement, sur des méthodes originales pour l’étude des modes transverses dans les fibres, sur des applications en métrologie laser (mesure de cohérence temporelle, mesure du facteur de Henry, perspective de mesure du taux d’émission spontané), et sur des applications métrologiques (réseaux de capteurs acoustiques, gyroscope) avec des alternatives systèmes permettant d’améliorer la sensibilité des capteurs étudiés. Les recherches menées sur la thématique desComposants et Systèmes THz se sont portées sur l’étude des sources térahertz par photo-mélange, et des détecteurs pour communications haut-débit sur porteuse THz. En terme de sources, la réalisation et l’étude expérimentale d’une source laser bifréquence de haute cohérence émettant à 1 μm a été présentée, avec la démonstration originale d’un fonctionnement laser bifréquence robuste en régime continu, basé sur la coexistence simultanée de deux modes transverses de Laguerre-Gauss dans un lasers à semi-conducteur émettant par la surface en cavité externe verticale (VeCSEL) pompé optiquement. L’excitation d’une photodiode à transport unipolaire a permis la démonstration d’une émission THz cohérente et accordable (50 – 700 GHz). En terme de détecteurs pour les communications, nous avons démontré pour la première fois la faisabilité d’une communication à très haut débit sur porteuse THz à l’aide de transistors à effet de champ, avec un record de 8,3 Gbps en modulation directe avec 400 μW de puissance incidente, et une communication à 1,5 Gbps en configuration hétérodyne avec seulement 56~μW de puissance incidente.Les projets de recherche présentés consistent en l’étude de nouveaux photo-conducteurs couplés au VeCSEL bi-fréquence réalisé, avec des photo-conducteurs plasmoniques pour un gain en puissance THz, et/ou des réseaux de photo-conducteurs qui épousent la géométrie du faisceau transverse multi-lobe issu du VeCSEL, ce intra- ou extra-cavité, afin de pouvoir augmenter de plusieurs ordres de grandeur la puissance THz en sortie, et éventuellement offrir une émission pulsée. En termes de détecteurs pour les communications, l’étude de l’adaptation large-bande en entrée et en sortie du transistor est une priorité, afin de pouvoir respectivement augmenter la sensibilité du transistor avec une antenne et de permettre son intégration avec les circuits électroniques rapides à sa sortie. Enfin, des études plus exploratoires seront menées en spectroscopie térahertz pour l’agronomie, notamment à l’aide des sources et détecteurs développés, ce dans la continuité d’un projet exploratoire initié dans le cadre du Labex Numev.

Development of a reliable, real-time, selective, sensitive and suitable technique for atmospheric trace gas spectroscopy is a critical challenge in science and engineering, for sanitary, ecological and industrial issues. Tunable single-frequency lasers in the 2µm to 3.3µm wavelength range, working in continuous regime at room temperature, can be used in absorption spectroscopy to identify and quantify several atmospheric gases. We report here on the design, the technological development and the performances of 1st and 2nd order index-coupled distributed-feedback (DFB) antimonide-lasers diodes in the 2µm to 3.3µm wavelength range. The first part of this document establishes the context of the thesis, introduces the DFB theory and our modelisation. The second part presents the technological fabrication of the two different components: the side wall corrugated DFB lasers and the buried DFB lasers. The third part shows the performances of the components and the first tests on gas measurement.This work has led to the development of two different kinds of single-frequency laser diodes with high optical power and spectral purity. The fabricated prototypes will soon be used on gas spectroscopy set-up.; Le développement d'un procédé de détection de gaz atmosphériques à l'état de traces en temps réel, fiable, robuste, sélectif, sensible et portable, est impératif pour répondre à des enjeux sanitaires, écologiques et industriels. La spectroscopie par diodes laser accordables est une des voies envisagées pour pourvoir à ce besoin. Elle nécessite le développement de diodes lasers mono-fréquences émettant en régime continu à température ambiante entre 2 µm et 3.3 µm. Nous reportons ici les modélisations et développements technologiques nécessaires à la fabrication de lasers à contre-réaction répartie – à couplage par l'indice, réseau du 1er et 2nd ordre, sur substrat antimoniure – ainsi que les résultats obtenus. Dans la première partie de ce document, après avoir dressé le contexte de l'étude, nous introduirons la théorie des lasers à contre-réaction répartie et présenterons les modélisations qui ont permis de décrire nos structures. La seconde partie est dédiée aux développements des procédés technologiques qui ont permis de mettre en place deux filières de fabrication de composants – à savoir des lasers DFB à ailettes et lasers DFB à réseau enterré. La troisième partie expose les performances des composants fabriqués et présente les premières mesures d'analyse de gaz effectuées. Ces travaux ont conduit au développement de deux nouvelles filières de fabrication de composants : des diodes lasers mono-fréquences présentant une puissance élevée et une forte sélectivité modale. Les prototypes fabriqués seront utilisés sur des systèmes de spectroscopie.