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Photonic jet: key role of injection for etchings with a shaped optical fiber tip
preprintposted on 2023-11-29, 05:06 authored by Robin Pierron, Julien Zelgowski, Pierre Pfeiffer, Joël Fontaine, Sylvain Lecler
We demonstrate the key role of the laser injection into a multimode fiber to obtain a photonic jet (PJ). PJ, a high concentrated propagating beam with a full width at half maximum smaller than the diffraction limit, is here generated with a shaped optical fiber tip using a pulsed laser source (1064~nm, 100~ns, 35~kHz). Three optical injection systems of light are compared. For similar etched marks on silicon with diameters around 1~$\mu$m, we show that the required ablation energy is minimum when the injected light beam is close to the fundamental mode diameter of the fiber. Thus, we confirm experimentally that to obtain a PJ out of an optical fiber, light injection plays a role as important as that of the tip shape, and therefore the role of the fundamental mode in the process.