Improved CW operation of GaAs-based QC lasers: T/sub max/= 150 K

Page, H.; Dhillon, Sukhdeep; Calligaro, M.; Becker, C.; Ortiz, V.; Sirtori, Carlo

doi:10.1109/jqe.2004.828259

Cited by 37 publications

(29 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The output characteristics of these structures are then evaluated using the full self-consistent rate equation model. 24,25 The results of the calculations performed for the existing structure show excellent agreement with the experimentally obtained values [13][14][15] and, at the same time, a noticeable improvement is predicted for the optimized QCLs.…”

Section: Introductionsupporting

confidence: 79%

“…Several mid-infrared GaAs-based QCL have achieved pulsed room temperature operation. [13][14][15][16][17] However, the output characteristics of these devices are still poor in comparison to InP based mid-infrared QCLs, demanding further optimization of layer structures and investigations of the influences of relevant physical and technological parameters. 18,19 As the GaAs/ AlGaAs system is lattice matched, the alloy composition and layer width can be varied independently.…”

Section: Introductionmentioning

confidence: 99%

“…[13][14][15]. Two types of active regions with appropriate injectors/collectors are developed, with the intention of focusing on two important design features: improved temperature behavior and a more efficient extraction mechanism.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Towards automated design of quantum cascade lasers

Mirčetić

Indjin

Ikonić

et al. 2005

Journal of Applied Physics

View full text Add to dashboard Cite

We present an advanced technique for the design and optimization of GaAs/ AlGaAs quantum cascade laser structures. It is based on the implementation of the simulated annealing algorithm with the purpose of determining a set of design parameters that satisfy predefined conditions, leading to an enhancement of the device output characteristics. Two important design aspects have been addressed: improved thermal behavior, achieved by the use of higher conduction band offset materials, and a more efficient extraction mechanism, realized via a ladder of three lower laser states, with subsequent pairs separated by the optical phonon energy. A detailed analysis of performance of the obtained structures is carried out within a full self-consistent rate equations model of the carrier dynamics. The latter uses wave functions calculated by the transfer matrix method, and evaluates all relevant carrier-phonon and carrier-carrier scattering rates from each quantized state to all others within the same and neighboring periods of the cascade. These values are then used to form a set of rate equations for the carrier density in each state, enabling further calculation of the current density and gain as a function of the applied field and temperature. This paper addresses the application of the described procedure to the design of ϳ 9 m GaAs-based mid-infrared quantum cascade lasers and presents the output characteristics of some of the designed optimized structures.

show abstract

Section: Introductionsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Towards automated design of quantum cascade lasers

Mirčetić

Indjin

Ikonić

et al. 2005

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…30 Achieving cw operation in midinfrared GaAsbased QCLs is a very challenging task due to the relatively high threshold current densities. Nevertheless, cw operation has been reported 29,32,33 with operating temperatures up to 150 K. 33 However, the output characteristics of midinfrared GaAs-based devices are still rather poor in comparison to InP-based midinfrared QCLs, which can lase in cw regime at room temperature. 6 For further improvements, a detailed knowledge of crucial design parameters as well as an understanding of relevant physical limitations of particular designs and further investigation of the influences of relevant physi-cal and technological parameters are highly desirable.…”

Section: Introductionmentioning

confidence: 99%

Influence of doping density on electron dynamics in GaAs∕AlGaAs quantum cascade lasers

Jovanović

Höfling

Indjin

et al. 2006

Journal of Applied Physics

View full text Add to dashboard Cite

A detailed theoretical and experimental study of the influence of injector doping on the output characteristics and electron heating in midinfrared GaAs/ AlGaAs quantum cascade lasers is presented. The employed theoretical model of electron transport was based on a fully nonequilibrium self-consistent Schrödinger-Poisson analysis of the scattering rate and energy balance equations. Three different devices with injector sheet doping densities in the range of ͑4 -6.5͒ ϫ 10 11 cm -2 have been grown and experimentally characterized. Optimized arsenic fluxes were used for the growth, resulting in high-quality layers with smooth surfaces and low defect densities. A quasilinear increase of the threshold current with sheet injector doping has been observed both theoretically and experimentally. The experimental and calculated current-voltage characteristics are in a very good agreement. A decrease of the calculated coupling constant of average electron temperature versus the pumping current with doping level was found.

show abstract

“…Influence of the injector doping, 14 the lattice temperature, 15 and carrier escape via weakly localized ⌫ states 16 were attributed as major limiting factors, for the high temperature operation and attainable gain, that determine the increase of I th and dynamic working range of ϳ9 m GaAs-based QCLs. Nevertheless, cw operation has been reported 10,17 with operating temperatures up to 150 K. However, the output characteristics are still inferior compared to InP MIR QCL. 18 Apart from ⌫-band related scattering, particularly in AlAs material, the importance of ⌫-X transport processes was examined in detail.…”

mentioning

confidence: 99%

Spectroscopy of GaAs∕AlGaAs quantum-cascade lasers using hydrostatic pressure

Jin

Ahmad

Sweeney

et al. 2006

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

The authors have measured the output spectrum and the threshold current in 9.2 m wavelength GaAs/ Al 0.45 Ga 0.55 As quantum-cascade lasers at 115 K as a function of hydrostatic pressure up to 7.3 kbars. By extrapolation back to ambient pressure, thermally activated escape of electrons from the upper lasing state up to delocalized states of the ⌫ valley is shown to be an important contribution to the threshold current. On the other hand leakage into the X valley, although it has a very high density of states and is nearly degenerate with the ⌫ band edge in the barrier, is insignificant at ambient pressure. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2364159͔Since the realization of the GaAs-based quantumcascade laser ͑QCL͒, 1 an impressive extension of the attainable infrared frequency range has been achieved. It can operate at wavelengths as long as 160 m, 2 or in dual frequency regime up to 215 m. 3 The design of GaAs/ AlGaAs QCLs can be made very flexible by varying the Al content due to naturally occurring near lattice matched material system across the full range of Al contents. Hence, following the terahertz emitting QCL, 4 several laser designs based on 15% Al content in the barriers were presented, approaching high temperature pulsed operation 5 or close to liquid nitrogen temperature cw operation. 6 GaAs-based QCLs emitting in the midinfrared ͑MIR͒ spectral region have so far used Al contents of 33%, 1 45%, 7-9 and 100%, 10-12 respectively, and have been subjected to a high external magnetic field. 13 Pulsed room temperature operation has been reported only for designs with 45% Al content 7-9 and for a hybrid GaAs/ InAs/ AlAs design. 11 Achieving cw operation in MIR GaAs-based QCLs is a very challenging task due to the relatively high threshold current densities ͑I th ͒. Influence of the injector doping, 14 the lattice temperature, 15 and carrier escape via weakly localized ⌫ states 16 were attributed as major limiting factors, for the high temperature operation and attainable gain, that determine the increase of I th and dynamic working range of ϳ9 m GaAs-based QCLs. Nevertheless, cw operation has been reported 10,17 with operating temperatures up to 150 K. However, the output characteristics are still inferior compared to InP MIR QCL. 18 Apart from ⌫-band related scattering, particularly in AlAs material, the importance of ⌫-X transport processes was examined in detail. 19,20 Recently, in the Sb-based QCLs the ⌫-X intervalley scattering is attributed as a possible limiting factor for the emission shorter than ϳ4 m. 21 The temperature sensitivity of the GaAs/ Al x Ga 1−x As QCL's I th decreases as the Al content increases from 33% to 45% in the barrier region. This is attributed to the increase in the activation energy for thermal escape 12 of electrons from the quantum well into the upper ⌫ miniband of the injector, which reduces its magnitude. However, at high Al concentrations the participation of lateral X and L valleys is believed to be an important factor deteriorating the device perfor...

show abstract

Improved CW operation of GaAs-based QC lasers: T/sub max/= 150 K

Cited by 37 publications

References 19 publications

Towards automated design of quantum cascade lasers

Towards automated design of quantum cascade lasers

Influence of doping density on electron dynamics in GaAs∕AlGaAs quantum cascade lasers

Spectroscopy of GaAs∕AlGaAs quantum-cascade lasers using hydrostatic pressure

Contact Info

Product

Resources

About