Single mode GaAs quantum cascade laser (original) (raw)
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High performance single mode GaAs quantum cascade lasers
We report on the realization of distributed feedback quantum cascade lasers in the AlGaAs=GaAs material system. Strong coupling is achieved by the use of a metalized surface relief grating, allowing the realization of short lasers. Continuous wave operation was achieved for an AlAs=GaAs chirped superlattice laser with an emission wavelength of 11:8 m. The used double plasmon enhanced optical waveguide consists only of the binary material GaAs and not of a ternary compound which results in a small thermal resistance. Further, the emission wavelength of the distributed feedback laser is continuously tunable according to the temperature dependence of the refractive index. Additionally, we want to report about pulsed single mode operation up to 335 K for a laser material, where Al0:45Ga0:55As is used for the barriers and GaAs for the wells. The emission wavelength is 9:5 m and the optical peak power in pulsed mode operation from one facet of the distributed feedback laser is 0:3 W at a temperature of 0 • C. ? 2002 Elsevier Science B.V. All rights reserved.
Infrared Quantum Cascade Laser
We report on quantum cascade lasers in the AlGaAs material system grown on GaAs. The emission wavelength is in the range of λ ~ 9.5-13 µm. Both, first and second order distributed feedback laser have been fabricated. A metallized surfacerelief grating is used for feedback to achieve single-mode emission. The emission wavelength is continuously tunable with the heat sink temperature. The second order distributed feedback lasers are efficient surface emitters with low beam divergence. Further, continuous wave operation at cryogenic temperatures has been achieved for a chirped superlattice active region.
Improved performance of GaAs-AlGaAs superlattice quantum cascade lasers beyond/spl lambda/= 13 μm
Highly improved quantum cascade lasers based on intraband transitions in a chirped AlGaAs-GaAs superlattice have been realized. Lasing in a liquid nitrogen environment with a laser wavelength centered at 13 m and with a peak optical power per facet exceeding 80 mW is achieved. A threshold current density of 8.6 kA/cm 2 at 80 K has been measured. Multimode lasing spectra ranging from 12.4 to 13.3 m and single mode spectra in a short cavity at 13 m are obtained. To improve the gain in the structure, the design of the injector is optimized. The minibands in the active region are more strongly confined beneath the conduction band edge of the barriers to decrease electron losses into the continuum. The maximum operating temperature exceeds 230 K with 0 values of 170 K. Index Terms-Environmental sensing, infrared spectroscopy, mid-infrared, semiconductor superlattices, unipolar semiconductor laser.
Improved performance of GaAs-AlGaAs superlattice quantum cascade lasers beyond /spl lambda/=13 μm
IEEE Photonics Technology Letters, 2000
Highly improved quantum cascade lasers based on intraband transitions in a chirped AlGaAs-GaAs superlattice have been realized. Lasing in a liquid nitrogen environment with a laser wavelength centered at 13 m and with a peak optical power per facet exceeding 80 mW is achieved. A threshold current density of 8.6 kA/cm 2 at 80 K has been measured. Multimode lasing spectra ranging from 12.4 to 13.3 m and single mode spectra in a short cavity at 13 m are obtained. To improve the gain in the structure, the design of the injector is optimized. The minibands in the active region are more strongly confined beneath the conduction band edge of the barriers to decrease electron losses into the continuum. The maximum operating temperature exceeds 230 K with 0 values of 170 K. Index Terms-Environmental sensing, infrared spectroscopy, mid-infrared, semiconductor superlattices, unipolar semiconductor laser.
Long wavelength (15 and 23 μm) GaAs/AlGaAs quantum cascade lasers
Quantum cascade lasers based on GaAs/AlGaAs chirped superlattice active regions have been achieved at wavelengths of 15 (sample A) and 23 µm (sample B). In pulsed mode they operate up to temperatures of 220 K and 100 K, respectively. Sample A employs a standard waveguide with n+-doped cladding, sample B was made with a metallic surface plasmon waveguide. The threshold current densities at cryogenic temperatures of 2.2 kA/cm 2 (A) and 10.2 kA/cm 2 (B) reflect the differences in intersubband lifetimes and waveguide losses close to the reststrahlenband.
Room temperature AlGaAs/GaAs quantum cascade lasers
Photonics Letters of Poland, 2011
The room temperature (293K), pulsed mode operation of a GaAs-based quantum cascade laser (QCL) is reported. This has been achieved by the use of GaAs/Al 0.45 Ga 0.55 As heterostructure. Its design follows an "anticrossed-diagonal" scheme. The QCL structures were grown by MBE in a Riber Compact 21T reactor. The double trench lasers were fabricated using standard processing technology, i.e., wet etching and Si 3 N 4 for electrical insulation. Double plasmon confinement with Al-free waveguide has been used to minimize absorption losses. High operating temperatures have been achieved by careful optimization of growth technology and using metallic high reflectivity facet coating on the back facet of the laser.
Intersubband and interminiband GaAs/AlGaAs quantum cascade lasers
Physica E: Low-dimensional Systems and Nanostructures, 2000
Electrically pumped injection lasers based on the GaAs=AlGaAs material system are investigated. Intersubband transitions in coupled quantum wells and intraband transitions in a ÿnite superlattice are used to demonstrate lasing. The laser emission wavelength is 10 m for the intersubband lasers and 12:9 m for the laser structure having a ÿnite superlattice as an active cell. Utilizing ridge waveguide laser bars at a heat-sink temperature of 10 K, peak optical powers of the intersubband quantum cascade lasers exceed 300 mW (interminiband: 100 mW). The maximum operating temperature is 160 K (interminiband: 50 K). Cylindrical micro-cavities show single-mode behavior with a side mode suppression ratio better than 25 dB for both kinds of lasers.
Gain-maximized GaAs/AlGaAs quantum-cascade laser with digitally graded active region
Applied Physics Letters, 2002
An advanced strategy for the optimal design and realization of a GaAs/AlGaAs quantum cascade laser is presented. It relies on recently established inverse spectral theory techniques based design of an optimal smooth active region profile, followed by the design of an almost equivalent digitally graded structure, comprising just two different alloy compositions. In order to compare the output characteristics of optimized and previously realized structures, the intersubband electron scattering transport in quantum cascade lasers is analysed. A full self-consistent rate equation model which includes all relevant electron-LO phonon and electron-electron scattering mechanisms between injector/collector, active region and continuum-like states is employed. Whilst the gain coefficients and threshold currents calculated at 77 K and 300 K for the structure with the triple quantum well active region show excellent agreement with recent experiments, a significant improvement of these parameters is predicted for the digitally graded quantum cascade laser. § τ 64 ¡ τ 96¨τ9 © z 96 2 , where (in our full 15level notation) the subscripts 9, 6 and 4 denote upper, lower and ground laser levels in active region, respectively , © ¤ 132 meV
Quantum cascade lasers at ∼ 16 μ m wavelength based on GaAs / AlGaAs
2018
Mid-infrared (3-30 μm) quantum-cascade (QC) lasers are usually designed and realized in InGaAs/AlInAs on an InP substrate. InP is a commonly-used substrate for semiconductor lasers because of its compatibility with InGaAs and AlInAs for tuning the depth of quantum wells in quantum-cascade lasers and its utility as a waveguide cladding material. However, its two-phonon resonance energy corresponds almost exactly to the energy of 16 μm photons, and so makes InP-based 16-μm QC lasers inefficient and low performing. 16 μm lasers are important for BTEX or UF6 sensors. GaAs is the next best substrate for such a laser. In this paper, we design a new 16-μm GaAs-based QC laser and provide the background understanding for QC lasers in general. The active and injector region period length is Lp = 520.4 Å. The figure of merit for the differential gain coefficient is 1.32, which is low, but it exhibits carrier inversion and would lase, making it a good preliminary design upon which to make modif...
Semiconductor …, 2004
Using microprobe photoluminescence we measured the electronic and lattice temperatures in operating quantum cascade lasers having similar chirped-superlattice active regions but different (GaAs/AlAs or GaAs/Al 0.45 Ga 0.55 As) conduction band discontinuities. Our results demonstrate the establishment of a thermalized hot-electron distribution. Coupling between the electronic ensemble and the lattice increases with the band-offset and influences the optical characteristics of the devices.