Semiclassical model for the relative intensity noise of intersubband quantum cascade lasers

Gensty, T.; Elsäßer, Wolfgang

doi:10.1016/j.optcom.2005.07.020

Cited by 55 publications

(34 citation statements)

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“…For example, it has been found experimentally, and verified theoretically, that the scaling behavior of the intensity noise as a function of the emitted power is different with respect to interband lasers, resulting directly from the cascaded level scheme and the different carrier lifetime. 2,3 The linewidth enhancement factor (␣ factor) determines the dynamics of semiconductor lasers, because it accounts for the coupling between amplitude and phase of the light as defined in Eq. (1),…”

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Measurements of the α factor of a distributed-feedback quantum cascade laser by an optical feedback self-mixing technique

et al. 2006

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We demonstrate measurements of the ␣ factor of a distributed-feedback quantum cascade laser (QCL) by using a newly modified self-mixing interferometric technique exploring the laser itself as the detector. We find a strong dependence of the ␣ factor on the injection current, ranging from −0.44 at 120 mA to 2.29 at 180 mA, which can be attributed to the inherent physics of QCLs. © 2006 Optical Society of America OCIS codes: 140.5960, 140.3070, 040.5570, 120.3180. Today, quantum cascade lasers (QCLs) have evolved to be among the most important light sources in the mid-infrared (MIR) to far-infrared (FIR) wavelength range. The lasing transition in QCLs occurs between subsequently cascaded quantized energy levels within the conduction band. Hence the emitted wavelength does not depend on the energy bandgap as in conventional semiconductor lasers, but it is determined by the energy difference of discrete levels in the conduction band originating from the bandgapengineered design of the laser device.1 With the advent of this new type of laser structure, a series of questions on the laser performance and the relevant physical mechanisms have been brought up. For example, it has been found experimentally, and verified theoretically, that the scaling behavior of the intensity noise as a function of the emitted power is different with respect to interband lasers, resulting directly from the cascaded level scheme and the different carrier lifetime.2,3 The linewidth enhancement factor (␣ factor) determines the dynamics of semiconductor lasers, because it accounts for the coupling between amplitude and phase of the light as defined in Eq. (1),Here, r and i are the real and the imaginary parts of the susceptibility, respectively, and n is the carrier density. 4 The ␣ factor therefore describes how gain and refractive index change with respect to each other when the carrier density varies.5 From the very beginning of the first technological realizations of QCLs, there has been an urgent need to measure the ␣ factor of QCLs and to check whether the particular level scheme gives rise to a different physics, e.g., ifQCLs exhibit an ␣ factor close to zero as expected for a nondetuned atomiclike level scheme. The standard technique used for interband semiconductor lasers is the Hakki-Paoli method, which relies on measuring the wavelength shift of the longitudinal laser modes below threshold. However, this method gives only access to ␣ values below threshold, and for low ␣ values its accuracy may be affected by temperature effects. 6 An approach based on injection locking 7 is the only method, to date, that has been applied to QCLs above threshold.Our purpose in this paper is fourfold. First, we apply the self-mixing (SM) technique to the MIR spectral range using QCLs. Second, by directly using the laser itself as a detector instead of an external photodetector, we are able to obtain nice and clean SM signals. Third, by applying a modified analysis method, we are able to extract the ␣ factor from the measurement of these wavefo...

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Measurements of the α factor of a distributed-feedback quantum cascade laser by an optical feedback self-mixing technique

et al. 2006

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“…1 in Ref. [12]). The carriers are injected into level 3, i.e., the upper laser level, by resonant tunneling.…”

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“…We consider the rate equations formulated by Gensty et al [11] and Gensty and Elsäßer [12]. The active region of a QC laser consists of a period of N p cascaded gain stages (N p = 25 − 35).…”

Section: Formulationmentioning

confidence: 99%

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Nonlinear dynamics of an injected quantum cascade laser

2013

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The stability properties of an injected quantum cascade laser are investigated analytically on the basis of current estimates of the laser parameters. We show that in addition to stable locking, Hopf bifurcations leading to pulsating intensities are possible. We discuss the stability diagrams in terms of the detuning and the injection rate for different values of the linewidth enhancement factor. The analysis indicates domains of coexistence between two stable steady states (bistability) or between a stable steady state and stable periodic oscillations. All predictions are verified numerically by determining bifurcation diagrams from the laser rate equations.

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“…2 and 3) self−consistently, we need to attain N i which can be fined from the laser rate equations [8,16] …”

Section: Simulation and Theoretical Modelmentioning

confidence: 99%

Modelling of GaN quantum dot terahertz cascade laser

Asgari

Khorrami

2013

Opto-Electronics Review

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In this paper GaN based spherical quantum dot cascade lasers has been modelled, where the generation of the terahertz waves are obtained. The Schrödinger, Poisson, and the laser rate equations have been solved self-consistently including all dominant physical effects such as piezoelectric and spontaneous polarization in nitride-based QDs and the effects of the temperature. The exact value of the energy levels, the wavefunctions, the lifetimes of electron levels, and the lasing frequency are calculated. Also the laser parameters such as the optical gain, the output power and the threshold current density have been calculated at different temperatures and applied electric fields.

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Semiclassical model for the relative intensity noise of intersubband quantum cascade lasers

Cited by 55 publications

References 29 publications

Measurements of the α factor of a distributed-feedback quantum cascade laser by an optical feedback self-mixing technique

Measurements of the α factor of a distributed-feedback quantum cascade laser by an optical feedback self-mixing technique

Nonlinear dynamics of an injected quantum cascade laser

Modelling of GaN quantum dot terahertz cascade laser

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