Negative refraction at telecommunication wavelengths through plasmon-photon hybridization.

We demonstrate negative refraction at telecommunication wavelengths through plasmon-photon hybridization on a simple microcavity with metallic mirrors. Instead of using conventional metals, the plasmonic excitations are provided by a heavily doped semiconductor which enables us to tune them into resonance with the infrared photon modes of the cavity. In this way, the dispersion of the resultant hybrid cavity modes can be widely adjusted.

Ultrafast Nonlinear Response of Bulk Plasmons in Highly Doped ZnO Layers.

Longitudinal bulk plasmons in an n-doped ZnO layer system are studied by two-color femtosecond pump-probe spectroscopy in the midinfrared. The optical bulk plasmon resonance identified in linear reflectivity spectra undergoes a strong redshift and a limited broadening upon intraband excitation of electrons. The nonlinear changes of plasmon absorption decay on a time scale of 2 ps and originate from the intraband redistribution of electrons.

Efficient light emission from inorganic and organic semiconductor hybrid structures by energy-level tuning.

The fundamental limits of inorganic semiconductors for light emitting applications, such as holographic displays, biomedical imaging and ultrafast data processing and communication, might be overcome by hybridization with their organic counterparts, which feature enhanced frequency response and colour range. Innovative hybrid inorganic/organic structures exploit efficient electrical injection and high excitation density of inorganic semiconductors and subsequent energy transfer to the organic semiconductor, provided that the radiative emission yield is high. An inherent obstacle to that end is the unfavourable energy level offset at hybrid inorganic/organic structures, which rather facilitates charge transfer that quenches light emission.

Calculating Optical Absorption Spectra of Thin Polycrystalline Organic Films: Structural Disorder and Site-Dependent van der Waals Interaction.

We propose a new approach for calculating the change of the absorption spectrum of a molecule when moved from the gas phase to a crystalline morphology. The so-called gas-to-crystal shift Δ[Formula: see text] is mainly caused by dispersion effects and depends sensitively on the molecule's specific position in the nanoscopic setting. Using an extended dipole approximation, we are able to divide Δ[Formula: see text] = - in two factors, where depends only on the molecular species and accounts for all nonresonant electronic transitions contributing to the dispersion while is a geometry factor expressing the site dependence of the shift in a given molecular structure.

Controlling the growth mode of para-sexiphenyl (6P) on ZnO by partial fluorination.

We report on the impact of partial fluorination of para-sexiphenyl (6P) on the growth mode when deposited on the non-polar ZnO(101̄0) surface. The evolution of the thin film structure and morphology is monitored by in situ atomic force microscopy and in situ real-time X-ray scattering. Both 6P and its symmetrical, terminally fluorinated derivative (6P-F4) grow in a highly crystalline mode, however, with a distinctly different morphology.