Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 12: HL Poster I

HL 12.24: Poster

Montag, 1. April 2019, 17:30–20:00, Poster E

Coupled Organic Microcavities with Balanced Gain and Loss for Experimental Studies on Non-Hermitian Physics — •Karla Roszeitis¹, Markas Sudzius¹, Hartmut Fröb¹, Jan Carl Budich², and Karl Leo¹ — ¹Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), TU Dresden, Germany — ²Institute for Theoretical Physics, TU Dresden, Germany

Photonic systems are perfect model systems to experimentally investigate topological effects. One way to achieve topological non-trivial phases is to construct a parity-time symmetric system, comprising gain and loss, leading to non-hermitian terms in the corresponding Hamiltonian. In our experiments we realize a parity-time symmetric setup, consisting of two coupled organic microcavities. While one cavity contains an absorbing dye (loss cavity), the other can be pumped with a 532-nm laser (gain cavity). By thoroughly tuning the pump power as well as other parameters (e.g. coupling strength between the cavities) we achieve a parity-time symmetric system with pronounced modes in the visible regime.

We model the above mentioned system by a non-hermitian Hamiltonian H of the form H = d(k) · σ. Here, d ∈ C is a vector with complex components, k denotes the wave vector, and σ the vector of Pauli matrices. By the interplay between theoretical analysis of the Hamiltonian and recording of spectra we predict and explain the non-hermitian behaviour of the spectrum, in particular the mode splitting. Further research will address the ability of the gain cavity to exceed lasing threshold, steering the system into non-linear regime.