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Abstract

Gold is useful for infrared polarization-insensitive mirrors on silica. However, gold does not adhere to bare silica. The adherence is enhanced by depositing an optically thin glue layer of Ni-P on a silica surface after sensitization of the surface with SnF.sub.2 and activation with PdCl.sub.2 /HCl. The Ni-P layer is deposited in a thickness sufficient to enhance adherence of gold to the surface of silica but insufficient to act as a barrier to the passage of infrared radiation to or from the gold layer. One measure of the Ni-P thickness is the absorbance of the glue layer of >0.008 at 550 nm (>0.003 at 850 nm) as measured by a spectrophotometer. A 100-150 nm thick gold layer, deposited by e-beam deposition on this adhesion layer, adheres well enough to pass the commonly used 'Scotch tape adhesion test'. The ability to make gold adhere to silica with very low optical loss is useful in fabrication of lightwave devices which require the use of reflecting surfaces, such as on optical fibers or waveguides.

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First Claim