Ultrashort pulse laser ablation through a multi-core fiber

Abstract

Ultrashort pulse laser ablation is a useful tool in material processing and biomedical fields [1]. A key challenge to expanding the applications of laser ablation is delivering high peak power, ultrashort laser pulses beyond the reach of conventional microscope objectives. Optical fiber endoscopes are widely used to guide light in confined spaces. However, the endoscopic delivery of a focused ultrashort pulse with peak power high enough to perform laser ablation is susceptible to nonlinear distortions or damage of the fiber itself. Focusing and scanning the pulse through single-mode fibers requires the use of distal optics, which will significantly increase the size of the endoscope. To bypass the current limitations in delivering, focusing and scanning a high peak power ultrashort pulse, we combine multicore fibers (MCFs) with wavefront shaping techniques. In this way, the pulse energy is spread between the thousands of cores of the MCF, thereby mitigating fiber damage and the nonlinearities when delivering an ultrashort pulse of high peak power. Additionally, the use of wavefront shaping techniques allows light to be focused and scanned at the distal end of a fiber without using any distal end optical components, thus maintaining an ultrathin size of the endoscope.