Fuentes Lorenzo, OmarVaiano, PatrizioDel Villar, IgnacioCorres Sanz, Jesús MaríaMatías Maestro, Ignacio2021-03-042021-08-2120201539-4794 (Electronic)10.1364/OL.402177https://academica-e.unavarra.es/handle/2454/39282The full width at half maximum (FWHM) of lossy mode resonances (LMRs) in the optical spectrum depends on the homogeneity of the thin film deposited. In this Letter, a method for improving the FWHM is applied for an LMR generated by a D-shaped optical fiber in reflection configuration. For this purpose, three samples with different attenuation were deposited with DC sputtering thin films of SnO2−x, and a further controlled immersion of the samples in water was performed. A laser-cleaner method was used to improve the FWHM characteristics of one of the samples from 106 to 53 nm. This improvement can be applied to thin-film-based sensors where there is a problem with the inhomogeneity of the coating thickness. Moreover, with this technique, it was proved that a coated length of just 3–4 mm permits the generation of an LMR, with implications for the miniaturization of the final device.5 p.application/pdfeng© 2020 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.Fiber lasersLaser ablationOptical fibersSensorsSurface plasmon resonanceThin filmsinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccess