High-temperature, high-power, continuous-wave operation of buried heterostructure quantum-cascade lasers

Evans, Arthur; Yu, Jae Su; David, J.P.R.; Doris, L.; Mi, K.; Slivken, S.; Razeghi, Manijeh

doi:10.1063/1.1641174

Cited by 138 publications

(76 citation statements)

References 10 publications

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“…[2][3][4][5][6][7] This is enabled by their complex structure, in which the sequence of alternating layers of different semiconductor materials is repeated many times. The first QCLs have been realized in the InGaAs/ AlInAs system, lattice matched on InP, and a significant improvement of the device performance, such as broad-band emission 8 or continuous wave room temperature 9 and ultrahigh power operation 10 has been achieved since. On the other hand, the GaAs/ AlGaAs system offers more growth flexibility, and since the first QCL realization 5 an impressive extension of the emission wavelength range from mid-infrared to terahertz 11,12 has been demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Towards automated design of quantum cascade lasers

Mirčetić

Indjin

Ikonić

et al. 2005

Journal of Applied Physics

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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.

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Section: Introductionmentioning

confidence: 99%

Towards automated design of quantum cascade lasers

Mirčetić

Indjin

Ikonić

et al. 2005

Journal of Applied Physics

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“…1 However, more than 20 years passed until the experimental realization was demonstrated by Faist et al at Bell Laboratories on an InP substrate. 2 Since then tremendous progress in QCL research has resulted in bidirectional, 3 multiwavelength, 3,4 ultrabroadband, 5 above room temperature continuous-wave ͑cw͒ operation, [6][7][8] sum-frequency and higher order harmonic generation, [9][10][11] and fully integrated electrically pumped Raman lasers. 12 Moreover, laser operation has been reported on other material systems, i.e., AlGaAs on a GaAs substrate 13 and Al͑Ga͒Sb on InAs.…”

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

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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.

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“…This device had no DFB structure and operated in single mode, most likely because of a small defect in the laser cavity. Recently, high-power cw QCLs have been developed to operate at 4.3-6 µm at power levels up to 600 mW [6], but as Fabry-Pérot devices these lasers exhibit multimode emission. More recently, new devices emitting at ∼ 9 and 5.4 µm with an embedded DFB structure have been developed [7,8].…”

Section: Introductionmentioning

confidence: 99%

Mid-infrared trace-gas sensing with a quasi- continuous-wave Peltier-cooled distributed feedback quantum cascade laser

et al. 2004

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A recently developed distributed feedback quantum cascade laser (QCL) capable of thermoelectric-cooled (TEC) continuous-wave (cw) operation and emitting at ∼ 9 µm is used to perform laser chemical sensing by tunable infrared spectroscopy. A quasi-continuous-wave mode of operation relying on long current pulses (∼ 5 Hz, ∼ 50% duty cycle) is utilized rather than pure cw operation in order to extend the continuous frequency tuning range of the quantum cascade laser. Sulfur dioxide and ammonia were selected as convenient target molecules to evaluate the performance of the cw TEC QCL based sensor. Direct absorption spectroscopy and wavelengthmodulation spectroscopy were performed to demonstrate chemical sensing applications with this novel type of quantum cascade laser. For ammonia detection, a 18-ppm noise-equivalent sensitivity (1 σ) was achieved for a 1-m absorption path length and a 25-ms data-acquisition time using direct absorption spectroscopy. The use of second-harmonic-detection wavelengthmodulation spectroscopy instead of direct absorption increased the sensitivity by a factor of three, achieving a normalized noiseequivalent sensitivity of 82 ppb Hz −1/2 for a 1-m absorption path length, which corresponds to 2 × 10 −7 cm −1 Hz −1/2 . PACS 42.55.Px; 42.62.Fi; 07.88.+y IntroductionTunable laser spectroscopy has proved to be a technique well suited for achieving gas-phase concentration measurements from the ppm level to the low ppb range. Compact laser sources that emit in the mid infrared, where most molecules exhibit fundamental and therefore strong absorption ro-vibrational bands, are particularly useful. Among the available tunable laser sources, distributed feedback (DFB) quantum cascade lasers (QCLs) offer several unique advantages for the design of compact field-deployable optical sensors, such as high output power, narrow laser line width, compactness, robustness, single-mode operation, and . Until now, due to the relatively short upper-state lifetime of the involved intersubband transitions occurring in QCLs, their high operating voltage of nearly 10 V, and the associated large heat dissipation within the active zone, single-frequency operation has been achieved only in a pulsed mode at room temperature. Pulsed QCL operation suffers from three drawbacks: (1) due to thermal chirping, even a ∼ 10-ns pulse generates typical QCL line widths of ∼ 200-300 MHz, which is substantially larger than the Fourier-transform limit; (2) the main sensitivity limitation of a pulsed DFB QCL based spectrometer arises from the pulse to pulse intensity fluctuations that require the use of an additional reference beam for normalization [3,4]; and (3) the generation of nanosecond current pulses requires high-speed driving electronics and detectors as well as fast data acquisition. To overcome these drawbacks, considerable effort has been made towards achieving a DFB QCL that is able to operate in a continuouswave (cw) mode at room temperature.A first device, employing high-reflection-coated facets and operating up t...

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High-temperature, high-power, continuous-wave operation of buried heterostructure quantum-cascade lasers

Cited by 138 publications

References 10 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

Mid-infrared trace-gas sensing with a quasi- continuous-wave Peltier-cooled distributed feedback quantum cascade laser

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