Tailoring the optical properties of wide-bandgap based microcavities via metal films

Abstract

We report on the tuning of the optical properties of II-VI-material-based microcavity samples, which is achieved by depositing Ag films on top of the structures. The micro-reflectivity spectra show a spectral shift of the sample resonance dependent on the metal layer thickness. By comparison of the experimental findings with the theoretical calculations applying the transfer matrix method on a metal-dielectric mirror structure, the influence of the metal layer particularly with regard to its partial oxidation was explored. Tamm plasmon modes are created at the interface between an open cavity with three ZnSe quantum wells and a metal layer on top. When tuning the excitonic emission relative to the mode by changing the sample temperature, an anticrossing of the resonances was observed. This is a clear indication that the strong coupling regime has been achieved in that sample configuration yielding a Rabi splitting of 18.5 meV. These results are promising for the realization of polariton-based optical devices with a rather simple sample configuration.

Observation of a hybrid state of Tamm plasmons and microcavity exciton polaritons

“…Four resonances can be observed in the reflectivity spectrum which is comparable to the calculated spectrum. The difference between the measurement and the calculation, especially the spectral linewidth of the lower and upper resonances, is mainly due to metal oxidation 24 and absorption losses which were not taken into account for the calculation. The presence of the TP mode which forms a hybrid TP-microcavity exciton polariton state is identified as being the reason for the formation of four resonances.…”

“…However, by employing Tamm plasmons (TPs) 22 23 which are formed at the interface between a metal and a distributed Bragg reflector (DBR) the trapping potential can be enhanced. The utilization of these TP resonances in order to observe strong coupling with QW excitons has already been reported 24 25 26 27 . An interesting technique has been proposed theoretically by Kaliteevski et al .…”

Influence of the sample design on the strong light-matter coupling in ZnSe-based periodic structures

“…In order to fully exploit the promising properties of a Bragg-polariton sample one has to achieve the strong coupling regime near room temperature without scaling up the fabrication effort. One possibility is the usage of a thin metal layer which can drastically increase the optical quality of the structure, as already reported [12]. To emphasize this idea, we present a micro-reflectivity measurement at RT of a planar cavity sample which consists of a 12-pair bottom DBR, a λ/2 cavity, and a 1.5-pair top DBR, as shown in Figure 2 (b).…”

Tamm Polaritons and Cavity Modes in the FIR Range

“…While the formation of plasmon-polaritons, with an exponentially decaying amplitude inside the metal is due to the negative dielectric constant of the metal below its plasma frequency, in the latter case the exciton has no role in the formation of the OTS but just couples to it. The metal film was used as adjustable means for making a microcavity (sometimes called Tamm microcavity) [8]. The purpose here is to extend these ideas to a different (namely FIR) spectral range and to find states at the interface between a polar semiconductor (such as GaAs) and a Bragg reflector suitable for the far-infrared (FIR) range.…”