Spinabhängige Polaritonstreuung und rein optische Kontrolle transversaler optischer Muster in Halbleitermikrokavitäten
Zusammenfassung der Projektergebnisse
Light is ideally suited for data transmission. However, signal processing in communication networks typically requires optical signals to be converted into electrical signals and then re-converted into optical signals for further transmission. Processing operations can only easily be implemented in electronic circuits. Purely optical approaches, however, would eliminate the neccessity to convert into electrical signals. A key element in optical circuits is an optical switch. Its characteristic feature is that a light signal is changed or switched by another light signal, e.g., in its amplitude, in its direction of propagation, or in its polarization state. Since electromagnetic light waves don’t interact directly, any such active control of light can only be achieved in nonlinear optical media. One approach to enable optical switching at very low light intensities is based on optical patterns. Besides switching at low intensities, in this approach a transistor-like response can be achieved in which a weak optical beam controls a stronger one, a pre-requisite for cascadability. The underlying nonlinear phenomenon, self organization, is ubiquitous in nature. Prominent examples are spontaneously formed regular spatial structures in water-flooded sand, animal coat patterns, or geographical variations in the population of parasitic insects. In these examples, as a result of nonlinearity, certain observables do not reflect the symmetry of the actual system, i.e., spatial homogeneity. In the present project we investigate a specific case of spontaneous symmetry breaking and self organization in planar quantum-well based semiconductor microcavites in which the fundamental optical excitations a the so-called polaritons. The system is spatially homogeneous in the quantum-well plane and plane-wave pump laser excitation in normal incidence does not spoil this symmetry. However, for pump excitation spectrally above the lower polariton branch, the system can spontaneously break its symmetry and exhibit a spatially non-homogeneous nonlinear optical response: above a certain pump threshold intensity stimulated off-axis scattering of pump-induced polaritons overcomes the intrinsic losses in the off-axis modes such that off-axis signals ‘spontaneously’ build up and are emitted from the cavity under a finite angle. It is the purpose of this project to obtain a fundamental understanding of the underlying microscopic many-particle physics and to explore the possibilities for external optical control of the patterns as a novel approach to efficient all-optical switching and control. Over the course of this project we have derived, studied, and implemented theoretical models with various different degrees of complexity. Our theoretical studies were performed in close collaboration with our experimental collaborators. Various aspects of polariton patterns were investigated as detailed in the numerous project-related publications. Key results include the realization of hexagonal polariton patterns and their optical control in a specifically designed double-cavity system, the derivation of a mode-competition model mapping the essentials of the complex electronic many-particle dynamics on a low-dimensional nonlinear dynamical systems including external control, the introduction of a novel optical control scheme with transistor functionality explicitly utilizing semiconductor-specific spindependent exciton-exciton scattering and its analysis within a low-dimensional extended Lotka-Voltera type model, the optical control of the optical spin-Hall effect, and the extension of the theoretical framework to optical parametric oscillation with polaritons emitting light with finite orbital angular momentum.
Projektbezogene Publikationen (Auswahl)
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“Patterns and switching dynamics in polaritonic quantum fluids in semiconductor microcavities“, Journal of the Optical Society of America B 33, C153 (2016)
N. H. Kwong, C. Y. Tsang, M.H. Luk, Y.C. Tse, P. Lewandowski, C. K. P. Chan, P.T. Leung, S. Schumacher, and R. Binder
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“Polarization dependence of nonlinear wave mixing of spinor polaritons in semiconductor microcavities“, Physical Review B 94, 045308 (2016)
P. Lewandowski, O. Lafont, E. Baudin, C. Y. Tsang, P. T. Leung, S. M. H. Luk, E. Galopin, A. Lemaitre, J. Bloch, J. Tignon, Ph. Roussignol, N. H. Kwong, R. Binder, and S. Schumacher
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“A population-competition model for analyzing transverse optical patterns including optical control and structural anisotropy“, New Journal of Physics 17, 083054 (2015)
Y. C. Tse, K. P. Chan, S. Luk, N. H. Kwong, P. T. Leung, R. Binder, and S. Schumacher
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“Controlling the optical spin Hall effect with light“, Applied Physics Letters 110, 061108 (2017)
O. Lafont, M. H. Luk, P. Lewandowski, N. H. Kwong, P. T. Leung, E. Galopin, A. Lemaitre, J. Tignon, S. Schumacher, E. Baudin, and R. Binder
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“Directional optical switching and transistor functionality using optical parametric oscillation in a spinor polariton fluid“, Optics Express 25, 31056 (2017)
P. Lewandowski, S. M. H. Luk, K.P. Chan, P.T. Leung, N. H. Kwong, R. Binder, and S. Schumacher
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“Optical switching of polariton density patterns in a semiconductor microcavity“, Physica Scripta 92, 034006 (2017)
N. H. Kwong, C. Y. Tsang, M.H. Luk, Y.C. Tse, C. K. P. Chan, P. Lewandowski, P.T. Leung, S. Schumacher, and R. Binder
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“Optically controlled orbital angular momentum generation in a polaritonic quantum fluid“, Physical Review Letters 119, 113903 (2017)
S. M. H. Luk, N. H. Kwong, P. Lewandowski, S. Schumacher, and R. Binder
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“Theory of optically controlled anisotropic polariton transport in semiconductor double microcavities“, Journal of the Optical Society of America B 35, 146 (2018)
S. M. H. Luk, P. Lewandowski, N. H. Kwong, E. Baudin, O. Lafont, J. Tignon, P.T. Leung, K.P. Chan, M. Babilon, S. Schumacher, and R. Binder
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“A transfer function replacement of phenomenological single-mode equations in semiconductor microcavity modeling“, Applied Optics (2020)
M. Carcamo, S. Schumacher, and R. Binder
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“Externally controlled Lotka Volterra dynamics in a linearly polarized polariton fluid“, Physical Review E 101, 012207 (2020)
M. Pukrop and S. Schumacher
