Fachgruppe Physik/Astronomiehttps://hdl.handle.net/20.500.11811/6462026-04-17T19:07:34Z2026-04-17T19:07:34ZStrong coupling between WS<sub>2</sub> monolayer excitons and a hybrid plasmon polariton at room temperatureZhang, YuhaoSchill, Hans-JoachimIrsen, StephanLinden, Stefanhttps://hdl.handle.net/20.500.11811/131092025-05-30T15:00:30Z2024-04-15T00:00:00ZStrong coupling between WS<sub>2</sub> monolayer excitons and a hybrid plasmon polariton at room temperature
Zhang, Yuhao; Schill, Hans-Joachim; Irsen, Stephan; Linden, Stefan
Light–matter interactions between plasmonic and excitonic modes have attracted considerable interest in recent years. A major challenge in achieving strong coupling is the identification of suitable metallic nanostructures that combine tight field confinement with sufficiently low losses. Here, we report on a room-temperature study on the interaction of tungsten disulfide (WS<sub>2</sub>) monolayer excitons with a hybrid plasmon polariton (HPP) mode supported by nanogroove grating structures milled into single-crystalline silver flakes. By engineering the depth of the nanogroove grating, we can change the character of the HPP mode from propagating surface plasmon polariton-like (SPP-like) to localized surface plasmon resonance-like (LSPR-like). Using reflection spectroscopy, we demonstrate strong coupling with a Rabi splitting of 68 meV between the WS<sub>2</sub> monolayer excitons and the lower HPP branch for an optimized nanograting configuration with 60 nm deep nanogrooves. In contrast, only weak coupling between the constituents is observed for shallower and deeper nanogratings since either the field confinement provided by the HPP is not sufficient or the damping is too large. The possibility to balance the field confinement and losses render nanogroove grating structures an attractive platform for future applications.
2024-04-15T00:00:00ZSpectroscopic Gas Sensor Based on a Fiber Fabry-Perot CavitySaavedra, CarlosPandey, DeepakAlt, WolfgangMeschede, DieterPfeifer, Hanneshttps://hdl.handle.net/20.500.11811/107482023-03-30T12:00:35Z2022-10-17T00:00:00ZSpectroscopic Gas Sensor Based on a Fiber Fabry-Perot Cavity
Saavedra, Carlos; Pandey, Deepak; Alt, Wolfgang; Meschede, Dieter; Pfeifer, Hannes
Optical spectroscopic sensors are powerful tools for analyzing gas mixtures in industrial and scientific applications. Whilst highly sensitive spectrometers tend to have a large footprint, miniaturized optical devices usually lack sensitivity or wideband spectroscopic coverage. By employing a widely tunable, passively stable fiber Fabry-Perot cavity (FFPC), we demonstrate an absorption spectroscopic device that continuously samples over several tens of terahertz. Both broadband scans using cavity mode width spectroscopy to identify the spectral fingerprints of analytes and a fast, low-noise scan method for single absorption features to determine concentrations are exemplary demonstrated for the oxygen A-band. The introduced scan method uses an injected modulation signal in a Pound-Drever-Hall feedback loop together with a lock-in measurement to reject noise at other frequencies. The FFPC-based approach provides a directly fiber-coupled, extremely miniaturized, light-weight, and robust platform for analyzing small analyte volumes that can straightforwardly be extended to sensing at different wavelength ranges, liquid analytes and other spectroscopic techniques with only little adjustments of the device platform.
2022-10-17T00:00:00ZFluctuation-Dissipation Relation for a Bose-Einstein Condensate of PhotonsÖztürk, Fahri EmreVewinger, FrankWeitz, MartinSchmitt, Julianhttps://hdl.handle.net/20.500.11811/107432023-03-30T09:30:42Z2023-01-20T00:00:00ZFluctuation-Dissipation Relation for a Bose-Einstein Condensate of Photons
Öztürk, Fahri Emre; Vewinger, Frank; Weitz, Martin; Schmitt, Julian
For equilibrium systems, the magnitude of thermal fluctuations is closely linked to the dissipative response to external perturbations. This fluctuation-dissipation relation has been described for material particles in a wide range of fields. Here, we experimentally probe the relation between the number fluctuations and the response function for a Bose-Einstein condensate of photons coupled to a dye reservoir, demonstrating the fluctuation-dissipation relation for a quantum gas of light. The observed agreement of the scale factor with the environment temperature both directly confirms the thermal nature of the optical condensate and demonstrates the validity of the fluctuation-dissipation theorem for a Bose-Einstein condensate.
2023-01-20T00:00:00Z