Energetic ion beams with diverse energies, species and beam dimensions have been extensively utilized to modify the properties of materials to achieve versatile applications in many aspects of industry, agriculture and scientific research. In optics, the ion‐beam technology has been applied to fabricate various micro‐ and submicrometric guiding structures on a wide range of optical crystals through the efficient modulation of the refractive indices or structuring of the surface, realizing various applications in many branches of photonics. The ion‐beam fabricated optical waveguides and other photonic structures have shown good guiding performance as well as properties related to the materials, suggesting promising potential for many aspects of photonics. This paper gives the state‐of‐the‐art review of fabrication, characterization and application on the ion‐beam‐processed micro‐ and submicrometric photonic structures by highlighting the most recent research progress. A brief prospect is presented by focusing on a few potential spotlights.

Two-dimensional transition metal dichalcogenides (TMDCs) exhibit excellent optoelectronic properties. However, the large band gaps in many semiconducting TMDCs make optical absorption in the near-infrared (NIR) wavelength regime impossible, which prevents applications of these materials in optical communications. In this work, we demonstrate that Ar ion irradiation is a powerful post-synthesis technique to tailor the optical properties of the semiconducting tungsten disulfide (WS) by creating S-vacancies and thus controlling material stoichiometry. First-principles calculations reveal that the S-vacancies give rise to deep states in the band gap, which determine the NIR optical absorption of the WS monolayer. As the density of the S-vacancies increases, the enhanced NIR linear and saturable absorption of WS is observed, which is explained by the results of first-principles calculations. We further demonstrate that by using the irradiated WS as a saturable absorber in a waveguide system, the passively Q-switched laser operations can be optimized, thus opening new avenues for tailoring the optical response of TMDCs by defect-engineering through ion irradiation.

We report the formation of optical waveguides in the self-Raman Nd:YVO(4) laser crystal by femtosecond laser inscription. The confocal fluorescence and Raman images have revealed that the waveguide is constituted by a locally compressed area in which the original fluorescence and Raman gains of the Nd:YVO(4) system are preserved. Thus the obtained structures emerge as promising candidates for highly efficient self-Raman integrated laser sources.

We report the improvement of ultrafast laser written optical waveguides in Yb:YAG ceramics by tailoring the presence of heat accumulation effects. From a combination of ytterbium micro-luminescence and micro-Raman structural analysis, maps of lattice defects and stress fields have been obtained. We show how laser annealing can strongly reduce the concentration of defects and also reduce compressive stress, leading to an effective 50% reduction in the propagation losses and to more extended and symmetric propagation modes.A. Benayas and W.F. Silva contributed equally to this work.

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We report on the microstructuring of Nd:YAG crystals by direct proton-beam writing. Buried channel waveguides have been fabricated with full spatial control by the combined variation of crystal position and proton energy. The fluorescence images of the obtained structures have been used to evaluate the potential application of the fabricated structures for laser gain as well as to elucidate the mechanism at the basis of the refractive index increment induced at the end of the proton path. We have concluded that this increment is very likely a local enhancement in the electronic polarizability caused by nuclear collisions.

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