At high current densities, the characteristics of organic laser diode structures are strongly influenced by a variety
of loss processes such as bimolecular annihilations, field-induced exciton dissociation and induced absorptions
due to polarons and triplet excitons. Here, we investigate a TE<sub>2</sub>-mode organic double-heterostructure laser diode
by numerical simulation. The electrical properties are described using a numerical drift-difusion model and the
optical characteristics are modeled using a transfer matrix method. When annihilation processes are included,
a threshold current density of 8.5 kA/cm<sup>2</sup> is derived for the considered device. Laser operation is not achieved
when field-induced exciton dissociation is considered. For induced absorptions, maximum relative cross sections
of 9.6 × 10<sup>-8</sup> for polarons and 1.4 × 10<sup>-4</sup> for triplet excitons have been calculated, which would still allow laser
operation. For higher relative absorption cross sections, laser operation is suppressed for all current densities.
Furthermore, the impact of field quenching is analyzed and the separation of singlet excitons from polarons and
triplet excitons in the time domain is studied.
The interaction of surface acoustic waves (SAWs) and light is spatially restricted to a region close to the surface approximately given by the acoustical wavelength. Therefore optical waveguides very close to the surface are required for high-frequency i.e. short-wavelength acoustic waves. In contrast to existing collinear integrated acoustooptical devices we are aiming at the regime where the optical and acoustical wavelengths are comparable. The periodically modulated refractive index caused by the SAWs may serve as a tunable and switchable optical add/drop comparable to fiber Bragg gratings, though not static. Another aspect of this regime is the phonon energy, which is non-negligible compared to the energy of the photons. So a significant energy shift i.e. wavelength conversion caused by scattering processes can be exploited. Existing integrated optical waveguides based on silica, SOI, lithiumniobate or III-V semiconductors are not suitable for a realization of such components, due to small piezoelectric coefficients or weak optical confinement. In contrast, heterostructures made of II-VI compounds are promising candidates for the proposed applications. Using Beam Propagation simulations we developed an optimized ridge waveguide structure based on a CdSe/CdS heterostructure, grown by molecular beam epitaxy. The waveguide is defined by wet-chemical etching using a standard photoresist mask. The mode field dimensions are about 1 μm x 2 μm, which requires fiber coupling using lensed fibers. We present measured coupling and propagation losses and discuss the integration with acoustical waveguides.