Ultra-Sharp Single-Crystal Nano Fiber Probes

We present how an effective fiber drawing process followed by low-cost and controllable etching enables atomically smooth YAG crystal fiber, producing high-crystallinity, defect-free, and ultra-sharp tapered probes with apexes down to 1.5 nm.

I. Introduction

Recently, single-crystal-fiber materials such as yttrium aluminium garnet (YAG) have emerged as a replacement of glass fibers for sensing applications [1]. Higher thermal conductivity and mechanical hardness [2], relatively narrow Raman signals [3], stronger damage threshold [4] as well as remarkable nonlinearity [5] are advantages of single-crystal materials compared with typical amorphous glass. Because of above advantages, single-crystal based optical fibers, or crystalline fibers, recently have attracted considerable interests [6]. However, fabrication of high-quality crystalline fibers with nanosized diameter is still challenging to date as result of limitation of growth technique.