Multimode RNGH instabilities of Fabry-Pérot cavity QCLs: impact of diffusion

Vuković, Nikola; Radovanović, J.; Milanović, V.; Boïko, D. L.

doi:10.1007/s11082-016-0515-0

Cited by 16 publications

(6 citation statements)

References 15 publications

(23 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As the pumping p is increased, the field and inversion can be solved for by the method of [33] as shown in Appendix E, the main results of which are stated here. We account for the population grating, but not the coherence grating which has been incorporated in recent work [56]. The primary modeẼ 0 grows according to…”

Section: B Population Gratingmentioning

confidence: 99%

Single-mode instability in standing-wave lasers: The quantum cascade laser as a self-pumped parametric oscillator

et al. 2016

View full text Add to dashboard Cite

We report the observation of a clear single-mode instability threshold in continuous-wave Fabry-Perot quantum cascade lasers (QCLs). The instability is characterized by the appearance of sidebands separated by tens of free spectral ranges (FSR) from the first lasing mode, at a pump current not much higher than the lasing threshold. As the current is increased, higher-order sidebands appear that preserve the initial spacing, and the spectra are suggestive of harmonically phase-locked waveforms. We present a theory of the instability that applies to all homogeneously broadened standing-wave lasers. The low instability threshold and the large sideband spacing can be explained by the combination of an unclamped, incoherent Lorentzian gain due to the population grating, and a coherent parametric gain caused by temporal population pulsations that changes the spectral gain line shape. The parametric term suppresses the gain of sidebands whose separation is much smaller than the reciprocal gain recovery time, while enhancing the gain of more distant sidebands. The large gain recovery frequency of the QCL compared to the FSR is essential to observe this parametric effect, which is responsible for the multiple-FSR sideband separation. We predict that by tuning the strength of the incoherent gain contribution, for example by engineering the modal overlap factors and the carrier diffusion, both amplitude-modulated (AM) or frequency-modulated emission can be achieved from QCLs. We provide initial evidence of an AM waveform emitted by a QCL with highly asymmetric facet reflectivities, thereby opening a promising route to ultrashort pulse generation in the mid-infrared. Together, the experiments and theory clarify a deep connection between parametric oscillation in optically pumped microresonators and the single-mode instability of lasers, tying together literature from the last 60 years.

show abstract

Section: B Population Gratingmentioning

confidence: 99%

Single-mode instability in standing-wave lasers: The quantum cascade laser as a self-pumped parametric oscillator

et al. 2016

View full text Add to dashboard Cite

show abstract

“…(14b), (14d), (14f) and (15b) a diffusion term 4k 2 c D describing the diffusion rate at which carriers diffuse away from peaks of the population grating. Here D denotes the diffusion constant, which for GaAs/AlGaAs systems is 46 cm 2 /s [19,40]. The fields f ± in Eq.…”

Section: A Maxwell-bloch Equations For a Fabry-perot Resonatormentioning

confidence: 99%

“…This paper addresses fully time dependent simulations of QCL comb operation based on the semi-classical Maxwell-Bloch (MB) laser equations [13]. Based on numerical solutions of the MB equations, mode-locking in QCLs and the emergence of coherent optical instabilities have been analyzed [14][15][16][17][18][19]. In those works, k-space dependence has not been included as it significantly increases the computational load involved and limits the simulation time to only short intervals [20].…”

Section: Introductionmentioning

confidence: 99%

Time domain modeling of terahertz quantum cascade lasers for frequency comb generation

Tzenov¹,

Burghoff²,

Hu³

et al. 2016

Opt. Express

View full text Add to dashboard Cite

The generation of frequency combs in the mid-infrared and terahertz regimes from compact and potentially cheap sources could have a strong impact on spectroscopy, as many molecules have their rotovibrational bands in this spectral range. Thus, quantum cascade lasers (QCLs) are the perfect candidates for comb generation in these portions of the electromagnetic spectrum. Here we present a theoretical model based on a full numerical solution of Maxwell-Bloch equations suitable for the simulation of such devices. We show that our approach captures the intricate interplay between four wave mixing, spatial hole burning, coherent tunneling and chromatic dispersion which are present in free running QCLs. We investigate the premises for the generation of QCL based terahertz combs. The simulated comb spectrum is in good agreement with experiment, and also the observed temporal pulse switching between high and low frequency components is reproduced. Furthermore, non-comb operation resulting in a complex multimode dynamics is investigated.

show abstract

“…This treatment of SHB can be extended by considering higher spatial frequencies of the inversion grating in Equation . Furthermore, it has been suggested to consider the formation of a grating, and its relaxation due to diffusion, also for the off‐diagonal density matrix elements in Equation …”

Section: Reduction To 1d Modelmentioning

confidence: 99%

Optoelectronic Device Simulations Based on Macroscopic Maxwell–Bloch Equations

Jirauschek

Riesch

Tzenov

2019

Advcd Theory and Sims

View full text Add to dashboard Cite

Due to their intuitiveness, flexibility, and relative numerical efficiency, the macroscopic Maxwell-Bloch (MB) equations are a widely used semiclassical and semi-phenomenological model to describe optical propagation and coherent light-matter interaction in media consisting of discrete-level quantum systems. This review focuses on the application of this model to advanced optoelectronic devices, such as quantum cascade and quantum dot lasers. The Bloch equations are here treated as a density matrix model for driven quantum systems with two or multiple discrete energy levels, where dissipation is included by Lindblad terms. Furthermore, the 1D MB equations for semiconductor waveguide structures and optical fibers are rigorously derived. Special analytical solutions and suitable numerical methods are presented. Due to the importance of the MB equations in computational electrodynamics, an emphasis is placed on the comparison of different numerical schemes, both with and without the rotating wave approximation. The implementation of additional effects which can become relevant in semiconductor structures, such as spatial hole burning, inhomogeneous broadening, and local-field corrections, is discussed. Finally, links to microscopic models and suitable extensions of the Lindblad formalism are briefly addressed. of a lower bandgap material than the adjacent layers, which restricts the free electron motion in that layer to the in-plane directions and gives rise to quantized energy states in growth direction. As a consequence of the further restriction of the energy spectrum and the even stronger carrier localization, additional improvement can be expected from 2D or 3D confinement, resulting in quantum wire/dash and quantum dot (QD) structures, respectively. Indeed, QD [1][2][3] and quantum dash [4] lasers and laser amplifiers have been shown to exhibit excellent characteristics. In Figure 1, the formation of quantized states in quantum wells, wires, and dots is schematically illustrated. The term quantum dash refers to an elongated nanostructure, that is, some kind of short quantum wire. By contrast, the term nanowire does not necessarily indicate strong quantum confinement. For example, in nanowire lasers, the nanowire geometry typically serves as a single-mode optical waveguide resonator, while the active region is based on a heterostructure or quantum well, as in a conventional laser diode. [5,6] Semiconductor optoelectronic devices usually rely on electron-hole recombination, that is, optical transitions between conduction and valence band states. The associated resonance wavelength is largely determined by the semiconductor bandgap, which establishes a lower bound on the transition energy. Thus, the coverage of a certain spectral region depends on the existence of suitable semiconductor materials, which for example restricts the availability of practical optoelectronic sources and detectors in the mid-infrared and terahertz regions. An alternative concept is based on intersubband devices, which employ so-called i...

show abstract

Multimode RNGH instabilities of Fabry-Pérot cavity QCLs: impact of diffusion

Cited by 16 publications

References 15 publications

Single-mode instability in standing-wave lasers: The quantum cascade laser as a self-pumped parametric oscillator

Single-mode instability in standing-wave lasers: The quantum cascade laser as a self-pumped parametric oscillator

Time domain modeling of terahertz quantum cascade lasers for frequency comb generation

Optoelectronic Device Simulations Based on Macroscopic Maxwell–Bloch Equations

Contact Info

Product

Resources

About