By conducting point-by-point inscription in a continuously moving slab of a pure fused silica at the optimal depth (170 μm depth below the surface), we have fabricated a 250-nm-period nanostructure with 30 nJ, 300 fs, 1 kHz pulses from frequency-tripled Ti:sapphire laser. This is the smallest value for the inscribed period yet reported, and has been achieved with radical improvement in the quality of the inscribed nanostructures in comparison with previous reports. The performed numerical modeling confirms the obtained experimental results.
 E. Wikszak, J. Burghoff, M. Will, S. Nolte, A. Tünnermann, T. Gabler, In: Conference on Lasers and Electro-Optics, 16–21 May 2004, San-Francisco, USA, OSA Trends in Optics and Photonics, 96, CThM7 (2004)
 A. Martinez, M. Dubov, I. Khrushchev, I. Ben-nion, In: Conference on Lasers and Electro-Optics CLEO/IQEC 2004, 16–21 May 2004, San-Francisco, USA, OSA Trends in Optics and Photonics, 96, CMY6 (2004)
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.