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Photoablation of synthetic fused quartz by simultaneous irradiation of multi-wavelength beams of a vacuum-ultraviolet (VUV) laser using high-order anti-Stokes Raman scattering is described. The VUV laser, which emits widely spread Raman-shifted lines from 133 nm to 594 nm, is ideal for effective laser ablation of the fused quartz. The well-defined patterns with a cross-sectional profile of a rectangular shape are formed by using a contact mask at an ablation rate as high as 13 nm/s. An effective absorption coefficient of 3.4×10-5 cm-1, which indicates that the multi-wavelength irradiation effect has an important role in the process, is obtained.

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We apply canonical Poisson-Lie T-duality transformations to bosonic open string worldsheet boundary conditions, showing that the form of these conditions is invariant at the classical level, and therefore they are compatible with Poisson-Lie T-duality. In particular the conditions for conformal invariance are automatically preserved, rendering also the dual model conformal. The boundary conditions are defined in terms of a gluing matrix which encodes the properties of D-branes, and we derive the duality map for this matrix. We demonstrate explicitly the implications of this map for D-branes in two non-Abelian Drinfel'd doubles.

Up-converted beams of a conventional quadrupled Nd:YAG laser by anti-Stokes Raman scattering in hydrogen are characterized as a vacuum ultraviolet light source. The beams diverge with the increase of the hydrogen pressure and also with the increase of the order of anti-Stokes scattering. Although the profiles of anti-Stokes beams vary from a Gaussian-like shape to a typical ring shape, the maximum energy conversion is always obtained with a near-Gaussian beam profile. The output energy ranges from 5.9 mJ for the first-order anti-Stokes wave (240 nm) to 8 μJ for the ninth-order anti-Stokes wave (133 nm). The energy of the sixth-order anti-Stokes wave (160 nm) fluctuates ±45% of the average output energy. The beam characteristics are described well by a model on the basis of phase matching between four waves related to each Raman process.