Intensity-modulated refractometer based on mode-mismatch in surface waveguides inscribed by femtosecond laser direct writing

• Tipo: Artigo em Revista Científica Internacional
• Data: 2021

Autores

Amorim, VA (Autor) Outra; Viveiros, D (Autor) FCUP; Maia, JM (Autor) Outra; Marques, PVS (Autor) FCUP

Revista

Título: Optics and Laser Technology

Vol. 135

ISSN: 0030-3992

Editora: Elsevier

Indexação

ISI Web of Knowledge - 2 Citações

Scopus - 2 Citações

Outras Informações

ID Authenticus: P-00T-1EZ

DOI: 10.1016/j.optlastec.2020.106723

Abstract (EN): Optical waveguides were fabricated at the surface of Eagle2000 glass substrates, using femtosecond laser direct writing and wet etching, and their potential as intensity-modulated refractometers was assessed. Through the analysis of their broadband spectral response to different refractive index oils, we observed that mode mismatch is present when the guided mode reaches the surface of the substrate and interacts with the external medium, thus enabling the use of such optical waveguides in refractive index sensing. Refractive indices equal to or greater than that of the substrate also induced a coupling mechanism that was shown not to be suitable in these devices. The device's wavelength of operation was found to be tunable by controlling the distance between the surface and the center of the optical waveguide. However, the sensitivity was seen to diminish by increasing the latter, being nonexistent for distances greater than 5.5 mu m. In this study, the maximum sensitivity values were found for a surface to core center distance between 1 and 2 mu m, in the biological range, and 2.5 to 3 mu m, for a refractive index nearing that of the substrate. Accordingly, maximum sensitivities of approximate to 25 dB/RIU and approximate to 1200 dB/RIU were found between 1.300 < n(D)(25)degrees(C) < 1.400 and 1.490 < n(D)(25)degrees(C) < 1.500, respectively.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 6