The infrared probe is the pivotal part of scanning near-infrared microscopy. The fabrication methods of it are different according to the different kinds of materials, most popular up to now is the adiabatic pulling of optical fibers during heating with CO2 laser and afterwards chemical etching. In this paper, a method of etching is presented; how to deal with the polymer and to strip away the Se-S layer, and how to etch inner core into a high quality tip are introduced in details. The production of large cone angles and smooth probe is further studied, Finally, we use the Beijing free electron laser as light source, The spectrum signals of GaN varying with different wavelengths were detected and analyzed under the near field condition, and obtained the primary result.