Highly power-efficient quantum cascade lasers

Liu, Peter Q.; Hoffman, Anthony J.; Escarra, Matthew D.; Franz, Kale J.; Khurgin, Jacob B.; Dikmelik, Yamaç; Wang, Xiaojun; Fan, Jen-Yu; Gmachl, Claire F.

doi:10.1038/nphoton.2009.262

Cited by 164 publications

(85 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…There will be more total output power at a given input power regardless of the cavity shape and gain mechanism, if the pumping distribution is chosen appropriately. When complemented with active-region quantum design [3,[31][32][33], spatially selective pumping can provide devices operating at optimal operation conditions and deliver maximal power under given fabrication and pump power constraints.…”

mentioning

confidence: 99%

Enhancement of laser power-efficiency by control of spatial hole burning interactions

Malik

Türeci

2014

Nature Photon

View full text Add to dashboard Cite

The laser is an out-of-equilibrium nonlinear wave system where the interplay of the cavity geometry and nonlinear wave interactions, mediated by the gain medium, determines the self-organized oscillation frequencies and the associated spatial field patterns. In the steady state, a constant energy flux flows through the laser from the pump to the far field, with the ratio of the total output power to the input power determining the power-efficiency. While nonlinear wave interactions have been modelled and well understood since the early days of laser theory, their impact on the power-efficiency of a laser system is poorly understood. Here, we show that spatial hole burning interactions generally decrease the power efficiency. We then demonstrate how spatial hole burning interactions can be controlled by a spatially tailored pump profile, thereby boosting the power-efficiency, in some cases by orders of magnitude.Power-efficiency of lasers is a key property to be maximized to reduce energy requirements for on-chip applications, facilitate thermal management and pack lasers into smaller volumes. Earlier work on solid-state lasers addressed the quantum design of the gain medium and the optimization of carrier transport, demonstrating strong improvements in power-efficiency [1,2]. Far less systematic work has addressed the fundamental factors limiting the power efficiency of lasers and effective methods to overcome these, taking into account specific resonator properties. In particular, the impact of spatial hole burning interactions is poorly understood [3]. A case in point are the findings of Ref. [4], where the output power of microcavity quantum cascade lasers was found to increase exponentially with boundary deformation, resulting in a power enhancement over two orders of magnitude with respect to identical lasers of circular cross-section. After more than a decade of theoretical development, the fundamental factors behind this dramatic increase in power efficiency remain unknown. The goal of this paper is to provide a theoretical analysis of the mechanisms at work that enable such dramatic improvements in laser power efficiency.Typically, the pump power in a microlaser is deposited uniformly across the entire cavity area [ Fig. 1(a)] and lasing naturally occurs in cavity modes with the longest cavity lifetimes. Here we show the existence of a maximally power-efficient "optimally out-coupled mode" that may never turn on in a uniformly pumped cavity due to spatial-hole burning interactions. We further show that a non-uniform pump distribution designed to selectively pump the optimally out-coupled mode can lead to strong power enhancements.Spatially non-uniform pump distributions can be realized by fabricating patterned contacts [5], by spatially non-uniform doping in the case of current injection lasers [6,7], or by using spatial light modulators or special lenses for optically pumped lasers [8,9] (see Fig. 1(b)). We discuss the optimal spatial profile of the pump for a given resonator to maximize the power effic...

show abstract

mentioning

confidence: 99%

Enhancement of laser power-efficiency by control of spatial hole burning interactions

Malik

Türeci

2014

Nature Photon

View full text Add to dashboard Cite

show abstract

“…The cascading mechanism was popularized by the well-known quantum cascade laser (QCL) [1][2][3][4][5] , which in fact has a very short (picosecond, ps) upper lasing level lifetime characteristic of intersubband transitions. In spite of this liability and thanks in part to the exceptionally weak temperature dependence of its threshold, QCLs now realize multi-watt CW output powers from single narrow ridges operating at room temperature (RT) 2,6 .…”

mentioning

confidence: 99%

Rebalancing of internally generated carriers for mid-infrared interband cascade lasers with very low power consumption

et al. 2011

View full text Add to dashboard Cite

The interband cascade laser differs from any other class of semiconductor laser, conventional or cascaded, in that most of the carriers producing population inversion are generated internally, at semimetallic interfaces within each stage of the active region. Here we present simulations demonstrating that all previous interband cascade laser performance has suffered from a significant imbalance of electron and hole densities in the active wells. We further confirm experimentally that correcting this imbalance with relatively heavy n-type doping in the electron injectors substantially reduces the threshold current and power densities relative to all earlier devices. At room temperature, the redesigned devices require nearly two orders of magnitude less input power to operate in continuous-wave mode than the quantum cascade laser. The interband cascade laser is consequently the most attractive option for gas sensing and other spectroscopic applications requiring low output power and minimum heat dissipation at wavelengths extending from 3 µm to beyond 6 µm.

show abstract

“…13,14 In this letter, we present the diagonal transition QCD, a design, where the active transition occurs between two energy levels, each localized in different, but adjacent wells. The same concept has been demonstrated for quantum cascade lasers, 15 by using a diagonal active transition, the upper laser lifetime could be increased, which eventually improved the slope efficiency and decreased the threshold current density. A diagonal transition QCD has generally a smaller overlap of the wave-functions of the active energy levels, where the non-optical scattering rate between the two levels is reduced, which enhances the extraction efficiency and resistance.…”

mentioning

confidence: 86%

Diagonal-transition quantum cascade detector

Reininger

Schwarz

Detz

et al. 2014

Applied Physics Letters

View full text Add to dashboard Cite

We demonstrate the concept of diagonal transitions for quantum cascade detectors (QCD). Different to standard, vertical QCDs, here the active transition takes place between two energy levels in adjacent wells. Such a scheme has versatile advantages. Diagonal transitions generally yield a higher extraction efficiency and a higher resistance than vertical transitions. This leads to an improved overall performance, although the absorption strength of the active transition is smaller. Since the extraction is not based on resonant tunneling, the design is more robust, with respect to deviations from the nominal structure. In a first approach, a peak responsivity of 16.9 mA/W could be achieved, which is an improvement to the highest shown responsivity of a QCD for a wavelength of 8 μm at room-temperature by almost an order of magnitude.

show abstract

Highly power-efficient quantum cascade lasers

Cited by 164 publications

References 10 publications

Enhancement of laser power-efficiency by control of spatial hole burning interactions

Enhancement of laser power-efficiency by control of spatial hole burning interactions

Rebalancing of internally generated carriers for mid-infrared interband cascade lasers with very low power consumption

Diagonal-transition quantum cascade detector

Contact Info

Product

Resources

About