Far-Infrared Quantum Cascade Lasers Operating in the AlAs Phonon Reststrahlen Band

Ohtani, K.; Beck, Mattias; Süess, Martin; Faist, Jérôme; Andrews, A. M.; Zederbauer, Tobias; Detz, Hermann; Schrenk, W.; Strasser, G.

doi:10.1021/acsphotonics.6b00750

Cited by 44 publications

(31 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…5 Activation-type behaviour of Auger process prohibits the operation of laser diodes based on narrow-gap materials at noncryogenic temperatures. [6][7][8] For this reason, quantum-cascade lasers (QCLs) become superior at 1-5 THz frequencies, 9 but they cannot operate in the 5-10 THz window 10,11 where lattice absorption and phonon-assisted depopulation of lasing levels are strong. 12 Still, laser diodes have much simpler design compared to QCLs, and if the problem of AR could be mitigated, they can beat QCLs in cost efficiency at most wavelengths.…”

mentioning

confidence: 99%

Fundamental Limits to Far-Infrared Lasing in Auger-Suppressed HgCdTe Quantum Wells

et al. 2019

View full text Add to dashboard Cite

A challenge of bridging the terahertz gap with semiconductor lasers faces an inevitable problem of enhanced non-radiative Auger recombination with reduction of photon energy. We show that this problem can be mitigated in mercury-cadmium-telluride quantum wells (HgCdTe QWs) wherein the Auger process is suppressed due to formation of quasi-relativistic electron-hole dispersion imposing strong energy-momentum restrictions on recombining carriers. Such dispersion is formed upon interaction of topological states at the two QW interfaces. We characterize the lasing properties of HgCdTe QWs quantitatively by constructing a microscopic theory for recombination, absorption, and gain, and show the feasibility of lasing down to ∼ 50 µm at liquid nitrogen temperature with threshold currents two orders of magnitude lower than in existing lasers. Our findings comply with recent experimental data on stimulated far-infrared emission from HgCdTe QWs and show the directions toward achievement of maximum possible lasing wavelength.

show abstract

mentioning

confidence: 99%

Fundamental Limits to Far-Infrared Lasing in Auger-Suppressed HgCdTe Quantum Wells

et al. 2019

View full text Add to dashboard Cite

show abstract

“…In fact, the corresponding energy range from 20 to 60 meV includes various molecular vibrations [1][2][3], as well as optical phonons in solids [4,5] and low-energy collective modes in correlated materials such as superconductors [6]. Quantum cascade lasers [7] provide a continuous wave source tunable in this spectral window. Pulses can also be produced by photoconductive switches [8,9] or via laser-induced air plasma generation [10][11][12].…”

mentioning

confidence: 99%

Coherent Field Transients below 15 THz from Phase-Matched Difference Frequency Generation in 4H-SiC

Fischer

Bühler

Kurihara

et al. 2017

Conference on Lasers and Electro-Optics

View full text Add to dashboard Cite

We experimentally demonstrate tunable, phase-matched difference frequency generation covering the spectral region below 15 THz using 4H-SiC as a nonlinear crystal. This material combines a non-centrosymmetric lattice and strong birefringence with broadband transparency at low optical frequencies. Thorough refractive index measurements in the terahertz spectral range allow us to calculate phase-matching conditions for any near-infrared pump laser source. 4H-SiC is also exploited as a detector crystal for electro-optic sampling. The results allow us to estimate the effective second-order nonlinear coefficient. The generation of coherent radiation in the spectral region between 5 and 15 THz is a major challenge for solid-state sources, despite its relevant interest for the study of fundamental excitations in condensed matter systems. In fact, the corresponding energy range from 20 to 60 meV includes various molecular vibrations [1][2][3], as well as optical phonons in solids [4,5] and low-energy collective modes in correlated materials such as superconductors [6]. Quantum cascade lasers [7] provide a continuous wave source tunable in this spectral window. Pulses can also be produced by photoconductive switches [8,9] or via laser-induced air plasma generation [10][11][12]. However, to obtain stable and intense electric fields combined with femtosecond temporal resolution, the workhorse approach relies on the generation of coherent field transients by frequency mixing processes in nonlinear crystals [13,14]. A typical setup is based on difference frequency generation (DFG) driven by an ultrafast laser system. Unfortunately, in the elusive spectral region between 5 and 15 THz, most nonlinear crystals applied for DFG such as GaSe, AgGaS 2 (AGS), and BBO, exhibit strong optical phonon resonances that lead to reststrahlen bands where radiation cannot penetrate into the material [see Fig. 1(a)]. In addition, isotropic materials such as ZnTe are lacking birefringence and, therefore, do not allow adjustment of phase matching. Furthermore, organic nonlinear crystals [15] show heavily structured spectra in the frequency range of interest and display inherently low damage thresholds. Recently, preliminary investigations by Naftaly et al.[16] suggested 4H-SiC as a crystal suitable for nonlinear optics in the multi-terahertz range. So far, this outstanding material has received little attention in experimental works that are limited to the demonstration of nonlinear properties in the near infrared [17], mid-infrared DFG above the optical phonon frequencies [18], and emission of 1 THz radiation from 6H-SiC [19].In this Letter, we experimentally demonstrate the application of 4H-SiC for the generation of ultrashort field transients tunable between 5 and 15 THz, and its use as an electro-optic sampling (EOS) crystal.SiC exhibits a large plurality of polymorphs with hexagonal, cubic, and rhombohedral symmetry [20]. Owing to its technological relevance, high-quality synthetic crystals of 4H-SiC are available. Its lattice, sketched in...

show abstract

“…The non-localized low-energy vibrational modes lying in the far-IR region also present a great potential for an efficient conformational discrimination [31] but, compared to the near-IR and UV domains, the available setups in this domain still lack of sensitivity. In a near future, new generation of QCL far-IR sources [32,33] will offer real opportunities to probe and resolve at low temperature the lowest energy vibrational bands of individual conformers even for highly flexible molecules characterized by a rich conformational landscape. The conformational analysis is, for these molecules, the first step for a correct determination of the vibrational cross sections.…”

Section: Discussionmentioning

confidence: 99%

Jet-cooled rovibrational spectroscopy of methoxyphenols using two complementary FTIR and QCL based spectrometers

Asselin

Bruckhuisen

Roucou

et al. 2019

The Journal of Chemical Physics

View full text Add to dashboard Cite

Methoxyphenols (MP) are a significant component of biomass burning emissions which mainly exists in our atmosphere in the gas phase where they contribute to the formation of secondary organic aerosols (SOA). Rovibrational spectroscopy is a promising tool to monitor atmospheric MPs and infer their role in SOAs formation. In this study, we bring a new perspective on the rovibrational analysis of MP isomers by taking advantage of two complementary devices combining jet-cooled environments and absorption spectroscopy: the Jet-AILES and the SPIRALES setups. Based on Q-branches frequency positions measured in the Jet-AILES FTIR spectra and guided by quantum chemistry calculations, we propose an extended vibrational and conformational analysis of the different MP isomers in their fingerprint region. Some modes such as far-IR out-of-plane-OH bending or mid-IR in-plane-CH bending allow to assign individually all the stable conformers. Finally, using the SPIRALES setup with three different EC-QCL sources centered on the 930-990 cm −1 and the 1580-1690 cm −1 ranges, it was possible to proceed to the rovibrational analysis of the ν 18 ring in-plane bending mode of the MP meta isomer providing a set of reliable excited state parameters which confirms the correct assignment of two conformers. Interestingly, the observation of broad Q-branches without visible P-and R-branches in the region of the CC ring stretching bands was interpreted as being probably due to a vibrational perturbation. These results highlight the complementarity of broadband FTIR and narrowband laser spectroscopic techniques to reveal the vibrational conformational signatures of atmospheric compounds over a large infrared spectral range.

show abstract

Far-Infrared Quantum Cascade Lasers Operating in the AlAs Phonon Reststrahlen Band

Cited by 44 publications

References 26 publications

Fundamental Limits to Far-Infrared Lasing in Auger-Suppressed HgCdTe Quantum Wells

Fundamental Limits to Far-Infrared Lasing in Auger-Suppressed HgCdTe Quantum Wells

Coherent Field Transients below 15 THz from Phase-Matched Difference Frequency Generation in 4H-SiC

Jet-cooled rovibrational spectroscopy of methoxyphenols using two complementary FTIR and QCL based spectrometers

Contact Info

Product

Resources

About