An electrically pumped polariton laser

Abstract

Conventional semiconductor laser emission relies on stimulated emission of photons, which sets stringent requirements on the minimum amount of energy necessary for its operation. In comparison, exciton-polaritons in strongly coupled quantum well microcavities can undergo stimulated scattering that promises more energy-efficient generation of coherent light by 'polariton lasers'. Polariton laser operation has been demonstrated in optically pumped semiconductor microcavities at temperatures up to room temperature, and such lasers can outperform their weak-coupling counterparts in that they have a lower threshold density. Even though polariton diodes have been realized, electrically pumped polariton laser operation, which is essential for practical applications, has not been achieved until now. Here we present an electrically pumped polariton laser based on a microcavity containing multiple quantum wells. To prove polariton laser emission unambiguously, we apply a magnetic field and probe the hybrid light-matter nature of the polaritons. Our results represent an important step towards the practical implementation of polaritonic light sources and electrically injected condensates, and can be extended to room-temperature operation using wide-bandgap materials.

Optical bistability in electrically driven polariton condensates

“…2(a). Confirming the observations that we have reported previously [9], we observe a double threshold in the input-output characteristics [35][36][37][38], which strongly suggests a crossover from the linear regime to polariton lasing (at j = 50 A/cm 2 , and a subsequent transition (at j = 110 A/cm 2 ) into the regime of cavity mediated from an electron-hole plasma. It is worth noting that while the second threshold into the weak coupling regime acquires the shape of a smooth S in the double logarithmic plot, the polariton lasing threshold features a sudden increase in intensity.…”

“…The intrinsic λ-thick GaAs Fabry-Pérot cavity spacer contains four InGaAs quantum wells (QWs). Strong coupling conditions are confirmed by photoreflection measurements and angular resolved electroluminescence for various excitonphoton detuning conditions, and we can extract a Rabi splitting of 5.5 meV (6 meV for a magnetic field of 5 T) [9]. In order to facilitate efficient current injection into the QWs, we etch micropillars with a diameter of 20 μm into the layer structure, which are later planarized by a polymer (benzocyclobuthene), and ring contacts are lithographically defined and evaporated on the top of the pillars.…”

“…Rather conveniently, polariton condensates can be generated optically [2,3], and electrical injection of polaritons in GaAs-based microcavities has also been demonstrated [9,10]. It is in particular the latter scheme which provides an entirely different platform for practical polariton devices, ranging from light sources with low power consumption to electrically controlled integrated circuits.…”

“…The sample which we study in this work is similar to the one discussed in Ref. [9]. It is composed of 23 (27) doped AlAs/GaAs distributed Bragg reflectors (DBRs) in the bottom (top) mirror.…”

Effects of optical polarization on hybridization of radiative and evanescent field modes

“…For a hybrid structure illustrated in Fig.1a, we encounter radiative field modes, such as photons and polaritons [13][14][15][16][17], as well as evanescent field modes, e.g., surface and graphene plasmons [18][19][20]. Research on optical responses of graphene electrons has been reported previously [20,21], but most of those efforts have been limited to the radiation or grating-deflection field coupling.…”