The preparation of epitaxial potassium-tantalate-niobate (KTa0.7Nb0.3O3, KTN) films on strontium-titanate substrates by means of pulsed excimer laser evaporation in vacuum is reported. In the most successful deposition experiments, a segmented evaporation target consisting of a semicircular KTN single crystal and a semicircular potassium nitrate pellet was utilized−to our knowledge for the first time; it was thus possible to overcome the otherwise observed partial loss of the volatile potassium and to avoid potassium deficiency in the KTN films. Rutherford backscattering spectrometry and x ray diffraction results indicate that the samples have the desired stoichiometric composition as well as the orientation prescribed by the substrate crystal.

Nonlinear optical polymers contain molecular dipoles with very large hyperpolarizabilities in a glassy polymer matrix. Two typical examples—a guest-host system with dispersed polar dye molecules and a side-chain material with chemically attached molecular dipoles—were investigated by means of poling experiments, dielectric spectroscopy, thermally stimulated depolarization, and electro-optical thermal analysis. The dielectric behavior of both polymers can be described by the phenomenological Havriliak–Negami equation, and the existence of master curves for both materials demonstrates the validity of the time-temperature superposition principle above the respective glass transitions. Temperature-dependent mean relaxation times and relaxation-time distributions calculated from the dielectric data allow for an optimization of poling times. The dielectric relaxation strengths obtained from poling current and field, from dielectric measurements, and from thermally stimulated depolarization are in very good agreement and thus represent a useful measure of the polarization in poled polymers. From the temperature dependence of the polarization, optimal poling temperatures may be derived. Electro-optical thermal analysis yields the same temperature-stability curves as thermally stimulated depolarization and is therefore a valuable tool for investigating the stability of poled polymers, especially since it is not sensitive to charge effects. Optimal poling fields and currents must be selected as a compromise between high dipole mobilities (short relaxation times) and low bulk conductivities.

Modal dispersion phase-matched second harmonic generation is demonstrated in new poled polymer waveguide geometries with a nonlinear optical core consisting of two side-chain polymers with different glass transition temperatures. After poling above and between the respective glass transitions, the sign of the nonlinear optical coefficient is reversed in the two polymers, thereby improving the overlap integral. Conversion efficiencies up to 7%/W cm2 were achieved in the first experiments

The sensitivity of a series of silicon trap detectors has been measured as a function of beam polarization. Measurements and numerical simulation show that very small departures from the ideal orientation of the photodiodes mounted in the trap induces a significant sensitivity to the state of polarization of the beam. Consequences of this polarization dependence for the use of trap detectors as transfer detectors in high-accuracy applications, particularly in cryogenic radiometry, are discussed.