Fabrication of multimode fiber tapers with a high reproducibility of the subwavelength extremity size: application to scanning near-field optical microscope probes

Abstract

A new method for the fabrication of multimode fiber tapers is presented. The process is aimed at elaborating fiber tips with a subwavelength size extremity. After creating a Biconical Taper (BT) with a standard fusion splicer, the elongated part is immersed in an HF acid solution. The light transmitted through the BT is collected by a photodiode, and thus the chemical etching is monitored by analysing the transmitted power. After calibration, it gives rise to a high reproducibility of the tip extremity with a subwavelength size. It has been applied to the fabrication of UV-Scanning Near-Field Optical Microscope probes. Multimode fibers are only available for UV light.