We have proposed a method to fabricate fiber probes for near-field optical microscopy based on electroless plating under ultrasonic irradiation. The method involves four steps: (A) chemically etching a high GeO_2 doped silica fiber in a buffered HF solution with a volume ratio of 40%NH_4F : 50%HF : H_2O= 10:1:1, (B, C) the surface activation by immersing in 1.0 g/dm^3-SnCl_2 and 5.0 mg/dm^3-PdCl_2 aqueous solutions, respectively, (D) electroless nickel plating under ultrasonic irradiation. Using 1MHz-PZT plate as the ultrasonic generator for this method, we succeeded in fabricating a near-field optical probe having a submicron-sized tip protruding from a nickel film with reproducibility.
