Investigating the Onset of the Strong Coupling Regime by Fine‐Tuning the Rabi Splitting in Multilayer Organic Microcavities. Issue 17 (27th June 2018)

• Record Type: Journal Article
• Authors: Tropf, Laura; Gather, Malte C.
• Is Part Of: Advanced optical materials. Volume 6:Issue 17(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-06-27
• Subjects: disorder -- excitons -- light–matter coupling -- polaritons -- small molecules; Optical materials -- Periodicals; Photonics -- Periodicals; 620.11295
• DOI: 10.1002/adom.201800203
• Languages: English
• ISSNs: 2195-1071

Abstract

Abstract: Given the prevalence of disorder in many organic semiconductors, the applicability of simple models to describe their behavior in the strong coupling regime, such as the two‐level coupled oscillator, is not evident. Here, the validity of the two‐level coupled oscillator model and the simple dependence of the coupling strength on the number of absorbers and the electric field is tested experimentally in metal‐clad microcavities containing a disordered film of small molecules. Multilayer microcavities are produced by combining different thin film deposition techniques. These allow for isolating the relevant parameters and thus to confirm the coupling strength is proportional to 1) the square root of the number of absorbers and 2) the amplitude of the electric field. By changing either of these two parameters, the microcavities are shifted from the weak to the strong coupling regime. Moreover, careful analysis reveals that there is a threshold coupling strength for the onset of the Rabi splitting. Two independent investigations show that this threshold is comparable to the losses in the cavities. These results validate the coupled two‐level Hamiltonian for microcavities containing disordered organic semiconductors, even though the assumption of a single exciton level represents a strong simplification for these systems. Abstract : The threshold for the onset of strong light–matter coupling is demonstrated to be comparable to losses in the system. Microcavities containing organic thin films are transitioned between the weak and strong coupling regimes by changing either the film position or film thickness. Both independent methods yield a threshold value for the coupling strength similar to the (dominating) photon losses.