A new scheme for stabilizing the carrier-envelope (CE) phase of a few-cycle laser pulse train is demonstrated. Self-phase modulation and difference-frequency generation in a single periodically poled lithium niobate crystal that transmits the main laser beam allows CE phase locking directly in the usable output. The monolithic scheme obviates the need for splitting off a fraction of the laser output for CE phase control, coupling into microstructured fiber, and separation and recombination of spectral components. As a consequence, the output yields 6-fs, 800-nm pulses with an unprecedented degree of short- and long-term reproducibility of the electric field waveform.

Polysilicon layers with thicknesses between 8 and 600 nm deposited by low-pressure chemical vapor deposition at temperatures ranging from 560 to 640°C were characterized by spectroscopic ellipsometry ͑SE͒ to determine the layer thicknesses and compositions using multilayer optical models and the Bruggeman effective-medium approximation. The dependence of the structural parameters on the layer thickness and deposition temperature have been investigated. A better characterization of the polysilicon layer is achieved by using the reference data of fine-grained polysilicon in the optical model. The amount of voids in the polysilicon layer was independently measured by Rutherford backscattering spectrometry ͑RBS͒. The SE and RBS results show a good correlation. The comparison of the surface roughness measured by SE and atomic force microscopy ͑AFM͒ shows that independently of the AFM window sizes, a good correlation of the roughness determined by SE and AFM was obtained.

The advantage of PARMS for the manufacturing of high performance low loss coatings is demonstrated with UV-and VIS band pass filter based on HfO2 respectively Nb2O5 and SiO2.

No abstract