Multiterawatt Hybrid (Solid/Gas) Femtosecond Systems in the Visible

A novel hybrid (solid/gas) approach to the development of femtosecond high‐intensity laser systems operating in the visible is presented in this chapter. Behind this approach is a combination of a solid‐state front end relying on widespread and highly developed techniques for femtosecond pulse generation in the near infrared with a photochemically driven boosting amplifier operating in the visible spectral range. Historical background of developing photochemically pumped gas lasers on broad bandwidth electronic transitions in molecules and physical principles of their operation are briefly summarized as well. The architecture and the design issues of the hybrid femtosecond systems relying on the amplification of the second harmonic of Ti:sapphire front ends in the photodissociation XeF(C‐A) power‐boosting amplifiers driven by the VUV radiation from electron‐beam‐to‐VUV‐flash converters are described, as well as breakthrough results of proof‐of‐principle experiments demonstrating a high potential of the hybrid approach. Wavelength scaling of laser‐matter interaction is shortly discussed to demonstrate advantages of shorter driver wavelengths for some applications with main emphasis placed on recombination‐pumped soft X‐ray lasers

Frank-Condon principle and adjustment of optical waveguides with nonhomogeneous refractive indices

The adjustment of two different selfocs is considered using both exact formulas for the mode-connection coefficients expressed in terms of Hermite polynomials of several variables and a qualitative approach based on the Frank-Condon principle. Several examples of the refractive-index dependence are studied and illustrative plots for these examples are presented. The connection with the tomographic approach to quantum states of a two-dimensional oscillator and the Frank-Condon factors is established.Comment: 8 pages, 4 figures, published version (layout of figures changed, typos corrected, references added

The Baikal Neutrino Telescope - Results and Plans

New results from the Baikal neutrino telescope NT200, based on the first 5 years of operation (1998-2003), are presented. We derive an all-flavor limit on the diffuse flux of astrophysical neutrinos between 20 TeV and 50 PeV, extract an enlarged sample of high energy muon neutrino events, and obtain limits on the flux of high energy atmospheric muons. In 2005, the upgraded telescope NT200+ will be commissioned: 3 additional distant strings with only 12 photo-multipliers each will rise the effective volume to 20 Mton at 10 PeV for this largest running neutrino telescope in the Northern hemisphere