Probability density tomography of microcavity polaritons confined in cylindrical traps of various sizes

Abstract

a b s t r a c tWe present the optical tomography of the probability density of microcavity polaritons, confined in three dimensions by cylindrical traps of various sizes. Collecting the photoluminescence emitted by the quasimodes under continuous nonresonant laser excitation, we reconstruct a three dimensional mapping of the photoluminescence, from which we can extract the spatial distribution of the confined states at any energy. We discuss the impact of the confinement shape and size on the probability density patterns. Microvavity polaritons are half-light half-matter quasiparticles, arising from the strong coupling between the electromagnetic mode of a semiconductor microcavity and a quantum well (QW) exciton [1]. The in-plane dispersion of the polaritons is dominated by their photonic component [2], and provides them with an effective mass 10 4 smaller than the free electron mass. Microcavity polaritons can therefore be confined in the in-plane directions by traps with sizes in the micrometer range. While the imaging of carriers confined in semiconductor heterostructures is generally forbidden due to the small confinement size, probability density (PD) patterns of polaritons confined in micrometer size traps can be accessed by standard optical means [3,4].We previously engineered a GaAs/AlAs microcavity with a single embedded InGaAs QW, featuring traps for the exciton-polaritons. These traps consist in quasi-circular mesas which were etched on the cavity spacer to locally enlarge the cavity length, thus providing a cylindrical confining potential for the photonic modes. More details about the sample and its fabrication are given in Ref. [5].

Coherent oscillations between orbital angular momentum polariton states in an elliptic resonator

“…The transverse mode patterns of these zero dimensional (0D) polariton states have been observed in traps of different sizes. 16 These patterns are similar to the optical mode profiles observed in cylindrical CdTe micropillars. 17 A spatially resolved spectrum of the photoluminescence emitted by the confined states in a 10 μm mean diameter trap under nonresonant pumping is shown in Fig.…”

“…2(a). Spatially resolved spectroscopy 16,17,[19][20][21][22] allowed to measure an energy splitting between |x and |y of E = 50 ± 25 μeV. These eigenstates can be selectively excited using resonant cw excitation.…”

Phase-resolved imaging of confined exciton-polariton wave functions in elliptical traps

“…5 A direct consequence of their small effective mass ͑or large de Broglie wavelength͒ is the possibility to confine polaritons in traps of sizes in the micrometer range. [6][7][8] Images of the two-dimensional distribution of the confined states probability density can be realized either using a tomography technique 9,10 or by directly imaging the coherent emission of a given state when it is resonantly excited with a continuous wave laser. 10,11 The emission intensity gives direct information on the probability density of the confined polariton states.…”

Magnetic Field Induced Redistribution of Exciton-Polariton Density on Confined Modes

“…1 and 2), starting from the mesa ground state. Their spatial proles are those of a quasi-cylindrical connement potential [9,12]. Figure 2 illustrates the PL spectra in the magnetic eld at 0 T, 2.5 T, and 5 T. We observe that the energy of the emission shifts to higher energy.…”

“…They have an advantage of having an extremely small eective mass of the order of 10 −4 of the free electron mass which allows to conne them inside three-dimensional traps of the size of several µm [57] or to manipulate their conned states [8]. The micrometer size of the traps allows to use standard optics for imaging the conned state wave function, giving the full information about the real space amplitude and phase [9]. This property makes them a very promising system in contrast to semiconductor quantum dots which are orders of magnitude smaller and for which there is no easy optical access to image single state wave function.…”