A new design for a terahertz quantum-cascade laser emitting at lambda˜80 mum is presented. A boun... more A new design for a terahertz quantum-cascade laser emitting at lambda˜80 mum is presented. A bound-to-continuum active region is coupled to an optical phonon extraction stage in order to improve the population inversion at high temperatures. The device processed with a single-plasmon waveguide shows a threshold current density in pulsed operation of Jthresh=190 A/cm^2 , sensibly lower of what measured in other optical-phonon based structures. Maximum operating temperature in pulsed mode is 100 K and peak powers of the order of 40 mW are observed at low temperatures. Device performances in a double-metal waveguide configuration reach 117 K in pulsed operation and 53 K in continuous-wave. This laser has been investigated also in presence of a strong magnetic field up to 27 T, in order to study the influence of an external confinement on the gain and lifetime of the electron states of a superlattice-based quantum cascade structure. Upon increasing of the magnetic field intensity, strong modulation of laser emission and threshold current are observed over the full range of magnetic field up to 27 T, with an overall reduction of the latter of a factor of two with respect to the zero field value. Spectral characterization in the presence of magnetic field has also been performed.
Conference Proceedings. 14th Indium Phosphide and Related Materials Conference (Cat. No.02CH37307), 2002
ABSTRACT We have succeeded to achieve highly efficient, narrow linewidth electroluminescence (EL)... more ABSTRACT We have succeeded to achieve highly efficient, narrow linewidth electroluminescence (EL) at room temperature from strained InGaAs quantum wire (QWR) light-emitting diodes (LEDs). The internal quantum efficiency is estimated to be as high as 60% for a single layer, 500-nm-pitch V-groove In0.15Ga0.85As QWR array LED, emitting at 1.29 eV (λ = 960 nm) with a linewidth as narrow as 14 meV. The high efficiency is achieved with the aid of selective carrier injection directly into the QWRs through self-ordered AlGaAs vertical quantum wells (VQWs), where the VQWs were separated from the InGaAs QWRs by thin GaAs spacer layers in order to reduce nonradiative recombination and inhomogeneous alloy broadening.
2007 Conference on Lasers and Electro-Optics (CLEO), 2007
Quantum cascade laser samples microdisks with double plasmon waveguiding were fabricated (λ≅80µm)... more Quantum cascade laser samples microdisks with double plasmon waveguiding were fabricated (λ≅80µm). High impedance mismatch between the confined optical mode and surrounding freespace allows the existence of whispering gallery modes 'unobtainable' in standard dielectric microdisks.
2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007
In this work we present results obtained on low frequency THz QCL immersed in strong magnetic fie... more In this work we present results obtained on low frequency THz QCL immersed in strong magnetic field. The devices, based on a intra-well transition, exhibit extremely low threshold currents (1 A/cm2 and below) due to the reduction of the non-radiative scattering processes obtained via the magnetic field-induced in-plane confinement .
2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006
Quantum cascade lasers emitting at 2.3, 1.66 and 1.39 THz are demonstrated. Active region is base... more Quantum cascade lasers emitting at 2.3, 1.66 and 1.39 THz are demonstrated. Active region is based on a large quantum well and magnetic field applied perpendicularly to the layers increases the gain enabling laser action.
Direct experimental evidences for excitonic lasing is obtained in optically pumped V-groove quant... more Direct experimental evidences for excitonic lasing is obtained in optically pumped V-groove quantum wire structures. We demonstrate that laser emission at a temperature of 10 K arises from a population inversion of localized excitons within the inhomogenously-broadened luminescence line. At the lasing threshold, we estimate a maximum exciton density of about 1.8 10 5 cm -1 .
Two families of photonic crystal based Terahertz Quantum Cascade Laser structures are demonstrate... more Two families of photonic crystal based Terahertz Quantum Cascade Laser structures are demonstrated. The first one uses Bragg mirrors that relies on a two-dimensional photonic lattice. Single mode lasing emission is observed from the edge of the structure for particular lattice constants. Moreover mode pinning of the laser is obtained along the whole dynamic range. In the second part a
2008 Conference on Lasers and Electro-Optics, 2008
... Sylvain Herminjard1, Lorenzo Sirigu1, Hans-Peter Herzig1, Eric Studemann2, Andrea Crottini2, ... more ... Sylvain Herminjard1, Lorenzo Sirigu1, Hans-Peter Herzig1, Eric Studemann2, Andrea Crottini2, Jean-Paul Pellaux2, Tobias Gresch3, Milan Fischer3, Jérôme Faist3 ... In order to access this spectral window, we developed a SPR-based optical sensor operating in the mid-infrared ...
Terahertz intersubband lasers based on different optical transitions are investigated under an in... more Terahertz intersubband lasers based on different optical transitions are investigated under an intense magnetic field applied perpendicularly to the plane of the epilayers, reaching the limit where the cyclotron energy exceeds many times the photon energy. Lasing thresholds as low as 0.65 A / cm 2 , together with a strong increase of the laser efficiency demonstrate the long intersubband relaxation times achieved in the intrawell samples by the induced three dimensional confinement. The radically different behavior observed for the bound-to-continuum structures highlights the role of interface roughness scattering at low energy subband spacing.
We demonstrate high spectral control from surface emitting THz Quantum Cascade Lasers based on a ... more We demonstrate high spectral control from surface emitting THz Quantum Cascade Lasers based on a two-dimensional photonic crystal cavity. The perforated top metallic contact acts as an in plane resonator in a tight double-metal plasmonic waveguide providing a strong optical feedback without needing three-dimensional cavity features. The optical far-field patterns do not exhibit the expected symmetry and the shape of the cavity mode. The difference is attributed to a metal surface plasmon mediated light outcoupling mechanism also responsible for the relatively low extraction efficiency.
We present the first optical sensor based on Surface Plasmon Resonance (SPR) operating in the mid... more We present the first optical sensor based on Surface Plasmon Resonance (SPR) operating in the mid-infrared range. The experimental setup is based on a Kretschmann geometry with Ti/Au layers deposited on a CaF(2) prism where light excitation is provided by a Quantum Cascade Laser (QCL) source. Evidence of SPR is presented and the sensing capability of the system is demonstrated by using CO(2) and N(2) mixtures as test samples. Due to the absorption of CO(2) at this wavelength, it is shown that the sensitivity of this configuration is five times higher than a similar SPR sensor operating in the visible range of the spectrum.
The authors fabricate and characterize a series of quantum cascade laser micropillars emitting at... more The authors fabricate and characterize a series of quantum cascade laser micropillars emitting at Ϸ3.5 THz. The optical confinement by double plasmon guiding in the vertical direction creates a large impedance mismatch between the confined optical modes and free space. Thus, unlike standard dielectric structures, large quality ͑Q͒ factors are maintained for small radius to wavelength ratios. The narrow bandwidth of the optical mode results in low threshold current ͑8 mA͒ single-mode lasers. Cavity pulling enables a fine dynamic tuning of the emission wavelength. Comparison of the frequency shift due to cavity pulling and the Stark effect provides an experimental measure of the gain ͑36 cm −1 ͒.
Demonstration of a terahertz quantum cascade laser grown by a low-pressure metalorganic vapor pha... more Demonstration of a terahertz quantum cascade laser grown by a low-pressure metalorganic vapor phase epitaxy is reported. The structural analysis of the grown structure shows a very high degree of vertical uniformity and sharp interfaces. Lasing emission at = 90 m up to 93 K with a threshold current density J th = 330 A / cm 2 at 7 K was obtained in a structure incorporating a single plasmon waveguide.
Multi-wavelength laser action in the terahertz (THz) region from a quantum cascade structure is d... more Multi-wavelength laser action in the terahertz (THz) region from a quantum cascade structure is demonstrated. Laser emission is obtained at 1.39 and 2.3 THz by using a structure based on a large single quantum well. A strong perpendicular magnetic field is employed to increase the gain and achieve laser action. In the second part of the work, a vertically emitting THz quantum cascade laser device that exploits an in-plane optical resonator based on a two-dimensional photonic crystal is demonstrated. Stable single mode vertical emission is reported. Simulations based on the block-iterative frequency-domain method on a plane wave basis account for the observed results.
A new design for a terahertz quantum-cascade laser emitting at lambda˜80 mum is presented. A boun... more A new design for a terahertz quantum-cascade laser emitting at lambda˜80 mum is presented. A bound-to-continuum active region is coupled to an optical phonon extraction stage in order to improve the population inversion at high temperatures. The device processed with a single-plasmon waveguide shows a threshold current density in pulsed operation of Jthresh=190 A/cm^2 , sensibly lower of what measured in other optical-phonon based structures. Maximum operating temperature in pulsed mode is 100 K and peak powers of the order of 40 mW are observed at low temperatures. Device performances in a double-metal waveguide configuration reach 117 K in pulsed operation and 53 K in continuous-wave. This laser has been investigated also in presence of a strong magnetic field up to 27 T, in order to study the influence of an external confinement on the gain and lifetime of the electron states of a superlattice-based quantum cascade structure. Upon increasing of the magnetic field intensity, strong modulation of laser emission and threshold current are observed over the full range of magnetic field up to 27 T, with an overall reduction of the latter of a factor of two with respect to the zero field value. Spectral characterization in the presence of magnetic field has also been performed.
Conference Proceedings. 14th Indium Phosphide and Related Materials Conference (Cat. No.02CH37307), 2002
ABSTRACT We have succeeded to achieve highly efficient, narrow linewidth electroluminescence (EL)... more ABSTRACT We have succeeded to achieve highly efficient, narrow linewidth electroluminescence (EL) at room temperature from strained InGaAs quantum wire (QWR) light-emitting diodes (LEDs). The internal quantum efficiency is estimated to be as high as 60% for a single layer, 500-nm-pitch V-groove In0.15Ga0.85As QWR array LED, emitting at 1.29 eV (λ = 960 nm) with a linewidth as narrow as 14 meV. The high efficiency is achieved with the aid of selective carrier injection directly into the QWRs through self-ordered AlGaAs vertical quantum wells (VQWs), where the VQWs were separated from the InGaAs QWRs by thin GaAs spacer layers in order to reduce nonradiative recombination and inhomogeneous alloy broadening.
2007 Conference on Lasers and Electro-Optics (CLEO), 2007
Quantum cascade laser samples microdisks with double plasmon waveguiding were fabricated (λ≅80µm)... more Quantum cascade laser samples microdisks with double plasmon waveguiding were fabricated (λ≅80µm). High impedance mismatch between the confined optical mode and surrounding freespace allows the existence of whispering gallery modes 'unobtainable' in standard dielectric microdisks.
2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007
In this work we present results obtained on low frequency THz QCL immersed in strong magnetic fie... more In this work we present results obtained on low frequency THz QCL immersed in strong magnetic field. The devices, based on a intra-well transition, exhibit extremely low threshold currents (1 A/cm2 and below) due to the reduction of the non-radiative scattering processes obtained via the magnetic field-induced in-plane confinement .
2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006
Quantum cascade lasers emitting at 2.3, 1.66 and 1.39 THz are demonstrated. Active region is base... more Quantum cascade lasers emitting at 2.3, 1.66 and 1.39 THz are demonstrated. Active region is based on a large quantum well and magnetic field applied perpendicularly to the layers increases the gain enabling laser action.
Direct experimental evidences for excitonic lasing is obtained in optically pumped V-groove quant... more Direct experimental evidences for excitonic lasing is obtained in optically pumped V-groove quantum wire structures. We demonstrate that laser emission at a temperature of 10 K arises from a population inversion of localized excitons within the inhomogenously-broadened luminescence line. At the lasing threshold, we estimate a maximum exciton density of about 1.8 10 5 cm -1 .
Two families of photonic crystal based Terahertz Quantum Cascade Laser structures are demonstrate... more Two families of photonic crystal based Terahertz Quantum Cascade Laser structures are demonstrated. The first one uses Bragg mirrors that relies on a two-dimensional photonic lattice. Single mode lasing emission is observed from the edge of the structure for particular lattice constants. Moreover mode pinning of the laser is obtained along the whole dynamic range. In the second part a
2008 Conference on Lasers and Electro-Optics, 2008
... Sylvain Herminjard1, Lorenzo Sirigu1, Hans-Peter Herzig1, Eric Studemann2, Andrea Crottini2, ... more ... Sylvain Herminjard1, Lorenzo Sirigu1, Hans-Peter Herzig1, Eric Studemann2, Andrea Crottini2, Jean-Paul Pellaux2, Tobias Gresch3, Milan Fischer3, Jérôme Faist3 ... In order to access this spectral window, we developed a SPR-based optical sensor operating in the mid-infrared ...
Terahertz intersubband lasers based on different optical transitions are investigated under an in... more Terahertz intersubband lasers based on different optical transitions are investigated under an intense magnetic field applied perpendicularly to the plane of the epilayers, reaching the limit where the cyclotron energy exceeds many times the photon energy. Lasing thresholds as low as 0.65 A / cm 2 , together with a strong increase of the laser efficiency demonstrate the long intersubband relaxation times achieved in the intrawell samples by the induced three dimensional confinement. The radically different behavior observed for the bound-to-continuum structures highlights the role of interface roughness scattering at low energy subband spacing.
We demonstrate high spectral control from surface emitting THz Quantum Cascade Lasers based on a ... more We demonstrate high spectral control from surface emitting THz Quantum Cascade Lasers based on a two-dimensional photonic crystal cavity. The perforated top metallic contact acts as an in plane resonator in a tight double-metal plasmonic waveguide providing a strong optical feedback without needing three-dimensional cavity features. The optical far-field patterns do not exhibit the expected symmetry and the shape of the cavity mode. The difference is attributed to a metal surface plasmon mediated light outcoupling mechanism also responsible for the relatively low extraction efficiency.
We present the first optical sensor based on Surface Plasmon Resonance (SPR) operating in the mid... more We present the first optical sensor based on Surface Plasmon Resonance (SPR) operating in the mid-infrared range. The experimental setup is based on a Kretschmann geometry with Ti/Au layers deposited on a CaF(2) prism where light excitation is provided by a Quantum Cascade Laser (QCL) source. Evidence of SPR is presented and the sensing capability of the system is demonstrated by using CO(2) and N(2) mixtures as test samples. Due to the absorption of CO(2) at this wavelength, it is shown that the sensitivity of this configuration is five times higher than a similar SPR sensor operating in the visible range of the spectrum.
The authors fabricate and characterize a series of quantum cascade laser micropillars emitting at... more The authors fabricate and characterize a series of quantum cascade laser micropillars emitting at Ϸ3.5 THz. The optical confinement by double plasmon guiding in the vertical direction creates a large impedance mismatch between the confined optical modes and free space. Thus, unlike standard dielectric structures, large quality ͑Q͒ factors are maintained for small radius to wavelength ratios. The narrow bandwidth of the optical mode results in low threshold current ͑8 mA͒ single-mode lasers. Cavity pulling enables a fine dynamic tuning of the emission wavelength. Comparison of the frequency shift due to cavity pulling and the Stark effect provides an experimental measure of the gain ͑36 cm −1 ͒.
Demonstration of a terahertz quantum cascade laser grown by a low-pressure metalorganic vapor pha... more Demonstration of a terahertz quantum cascade laser grown by a low-pressure metalorganic vapor phase epitaxy is reported. The structural analysis of the grown structure shows a very high degree of vertical uniformity and sharp interfaces. Lasing emission at = 90 m up to 93 K with a threshold current density J th = 330 A / cm 2 at 7 K was obtained in a structure incorporating a single plasmon waveguide.
Multi-wavelength laser action in the terahertz (THz) region from a quantum cascade structure is d... more Multi-wavelength laser action in the terahertz (THz) region from a quantum cascade structure is demonstrated. Laser emission is obtained at 1.39 and 2.3 THz by using a structure based on a large single quantum well. A strong perpendicular magnetic field is employed to increase the gain and achieve laser action. In the second part of the work, a vertically emitting THz quantum cascade laser device that exploits an in-plane optical resonator based on a two-dimensional photonic crystal is demonstrated. Stable single mode vertical emission is reported. Simulations based on the block-iterative frequency-domain method on a plane wave basis account for the observed results.
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Papers by Lorenzo Sirigu