Very short wavelength (λ=3.1–3.3μm) quantum cascade lasers

Abstract

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.

Midinfrared GaInSb∕AlGaInSb quantum well laser diodes grown on GaAs

“…However, for most of the important 3 -4 m spectral band, there are currently no practical high-temperature semiconductor lasers. Although much progress has been made in the development of "short wavelength" quantum cascade lasers ͑QCLs͒, with room temperature pulsed laser emission at a wavelength of 4.1 m in InGaAs/ AlAsSb/ InP strain compensated devices, 2 240 K pulsed laser emission at ϳ 3.2 m from InAs/ AlSb devices, 3 and low temperature pulsed laser operation at ϳ 3.1 m for both InP based strain compensated InGaAs/ InAlAs/ AlAs ͑Ref. 4͒ and lattice matched InGaAs/ AlAsSb, 5 only one QCL operating continuous wave ͑cw͒ at room temperature and at wavelengths below 4.0 m has been reported.…”

Deterministic emitter-cavity coupling using a single-site controlled quantum dot

“…⌫ c is set to 100 eV which is a conservative estimate based on test structures fabricated using dot ensembles. 26 ⌫ x Ј is set to 50 eV, which is the typical measured linewidth of the site-controlled InAs/InP dots ͓see inset, Fig. 1͑c͔͒.…”

“…The cavity design is based on a modified single missing hole defect 25 that is robust against process-and tuning-induced variations of the cavity geometry, with Q-values of 10 000-15 000. 26 Optical measurements are done at 4.2 and 40 K in a continuous flow helium cryostat using nonresonant, above band-gap excitation through a 50X microscope objective ͑N.A. = 0.42͒.…”

Quantum cascade lasers as metrological tools for space optics

“…QC lasers recently used as LOs in mid-infrared heterodyne spectrometers [2,3], on the contrary, have proved to be able to replace CO2 lasers in terms of emitted power, overcoming at the same time the limitations on the spectral range. At present, in fact, cw QC lasers working in the range from 3 m to several tens of m have been demonstrated [4,5,6]. A second aspect in which QCLs represent an important improvement in comparison to CO2 lasers is the tunability.…”