Line patterning with large refractive index changes in the deep inside of glass by nanosecond pulsed YAG laser irradiation

Nanosecond (∼100 ns) pulsed (10 Hz) Nd:YAG laser operating at the wavelength (λ) of 1064 nm with pulse energies of 0.16–1.24 mJ/cm2 has irradiated 10Sm2O3·40BaO·50B2O3 glass. It is demonstrated for the first time that the structural modification resulting the large decease (∼3.5%) in the refractive index is induced by the irradiation of YAG laser with λ=1064 nm. The lines with refractive index changes are written in the deep inside of 100–1000 μm depths by scanning laser. The line width is 1–13 μm, depending on laser pulse energy and focused beam position. It is proposed that the samarium atom heat processing is a novel technique for inducing structural modification (refractive index change) in the deep interior of glass.