Intrinsic second harmonic generation from un-poled doped silica multilayered thin films.

Abstract

[EN]Second harmonic light generation (SHG) was observed from as-deposited silica glass thin films suitable for waveguiding, without the need for an inversion symmetry-breaking poling treatment. Thin film stacks of up to 16 layers of alternating 2% phosphorus-doped and undoped silica glass on silica substrates were prepared and probed with a pulsed Nd:YAG laser at 1064 nm. We observed that even though these structures were not poled, they possess a net second order non-linearity with a value of the order of 0.03 pm/V. The SHG increased with the number of layers (total thicknesses between 4 and 9.6 µm have been tested) and also depended on the thickness ratio between the doped and undoped layers. Annealing at 800°C for 4 hours removed the nonlinearity completely.