Abstract

The optical encoding of χ⁽²⁾ gratings in silica-based glasses with light and its second harmonic (SH) has exhibited a variety of effects related to the phase and intensity of the encoding beams. Previous studies in germane silicate fibers have demonstrated that simultaneity of the writing pulses is needed for encoding optimum effective χ⁽²⁾ values. These observations were complicated, however, by modal-dispersion and group-velocity effects and by the fact that the fibers are longer than the pulses themselves.¹ In this work we report on the results of writing pulse-delay effects in bulk- samples of lead-oxide-doped (F8) and barium-oxide-doped (SK5) silicate glasses as well as a germanosilicate fiber preform (~4% GeO₂). In another set of experiments, we used simultaneous writing pulses at 1.064 μm and 5S2 nm preceded by a 1.064-μm or 532-nm pulse in an attempt to understand the possible role of absorption in the encoding process.

© 1993 Optical Society of America