A method to coat a 50 nm golden film with a plasma sputtering apparatus was proposed. By considering low sensitivity on Surface Plasmon Resonance(SPR) mode mixing of multimode fibers and simulation difficulty

a SPR sensing probe of single mode fiber with the wedge structure was introduced experimentally. Firstly

the effects of parameters such as vacuum degree

electric current

distance and time on film properties and film depths were studied. The film thickness was calibrated by a profilometer and the effect of film thickness on SPR exciting phenomenon was measured by a modified SPR measurement system with a space prism. The 630 nm single mode fiber was polished into a wedge structure by fiber grinding technology

and the 50 nm golden film was coated on the inclined plane of the wedge to realize the Kretchmann prism structure on the single mode fiber. Under a microscope

the end face of multi-mode fiber with 105 m diameter of fiber core was directed at a total reflection beam and fixed to collect the reflection light of SPR

where the sensing property and reflective index of SPR single mode fiber with the wedge structure were studied. The results show that the golden film is well coated with (505) nm film thickness under the conditions of 210

-1

Pa vacuum degree

5 mA electric current

1 cm sputtering distance and 3.5 min sputtering time. When grinding angel is 15

the SPR sensor of single mode fiber with wedge structure is sensitive to liquid with refractive index between 1.333 and 1.385 and the working range of resonance valley is between 693 nm and 924 nm with the mean sensitivity of 4 442 nm/RIU. The proposed ion sputtering equipment meets the demand of SPR experiment and the SPR probe of single mode fiber with wedge construct is characterized by high sensitivity

simple procedures and great application potential.