Fabrication of strong long-period gratings in hydrogen-free fibers with 157-nm F2-laser radiation.

Long-period gratings were fabricated in standard telecommunication fiber (Corning SMF-28) by use of what is believed to be record short-wavelength light from a 157-nm F(2) laser. Strong loss peaks were formed without the need for enhancement techniques such as hydrogen loading. The magnitude of the attenuation peak was sensitive to the single-pulse laser fluence, decreasing with increasing pulse fluence as a result of nonuniform 157-nm laser interaction with both the fiber cladding and core. The long-period fiber gratings have good wavelength stability (Dlambda~7 nm) under thermal annealing at 150 degrees C.

Tunable extreme-ultraviolet radiation from 105 to 87.5 nm using Hg vapor.

Tunable, coherent radiation has been generated in the region 105 to 87.5 nm by resonant four-wave frequency mixing in Hg vapor. A glass capillary array forms an efficient XUV window with 50% transmission. An absorption spectrum of N(2) was recorded at 89 nm with a resolving power of 2 x 10(5).