Electric field induced structural modification and second order optical nonlinearity in potassium niobium silicate glass

• Second harmonic generation properties have been studied in 23 K2O center dot 27Nb(2)O(5) center dot 50 SiO2 glass subjected to thermal poling. The poling-induced optical nonlinearity. with chi((2)) = 3.8 pm/V, has been related to structural modifications within a surface layer of a few microns on the anode side, as evidenced by means of confocal micro-Raman mapping along the sample thickness. The data indicate that the structural changes result from a charge transport process that causes network modifications in an alkali depleted layer whose thickness is comparable with that of the non-linear region. The Raman data also indicate that in the alkali depleted layer the network polymerization degree increases as a consequence of ion migration. The origin of the nonlinearity and the mechanisms activated by poling are discussed. The mechanism of non-bridging-oxygen to bridging-oxygen bond switching is proposed to explain ion migration and the subsequent structural changes in the glass.

Keyword

Non-linear optics

Raman spectroscopy

Silicates

Poling

ionic-transport-properties

2nd-harmonic generation

borophosphate

glasses

atomic-structure

blocking anode

oxide glasses

surface

sodium

irradiation

depletion

Publication and Content Type

ref (subject category)

art (subject category)