Inscription of surface waveguides in glass by femtosecond laser writing for enhanced evanescent wave overlap

• Type: Article in International Scientific Journal
• Date: 2020

Authors

Amorim, VA (Author) Other; Maia, JM (Author) Other; Viveiros, D (Author) FCUP; Marques, PVS (Author) FCUP

Journal

Title: Journal of Optics

Vol. 22

ISSN: 2040-8978

Publisher: Institute of Physics Publishing

Indexing

ISI Web of Knowledge - 5 Citations

Scopus - 5 Citations

Other information

Authenticus ID: P-00S-HPK

DOI: 10.1088/2040-8986/aba03f

Abstract (EN): Near-surface optical waveguides were fabricated in alkaline earth boro-aluminosilicate glass (Eagle2000), by femtosecond laser direct writing, using two distinct approaches. First, the capability of directly inscribing optical waveguides close to the surface was tested, and then, compared to the adoption of post writing wet etching to bring to the surface waveguides inscribed at greater depths. Laser ablation was found to limit the minimum surface to core center distance to 6.5 mu m in the first method, with anisotropic wet etching limiting the latter to 3 mu m without any surface deformation; smaller separations can be achieved at the cost of the planar surface topography. Furthermore, the waveguide's cross-section was seen to vary for laser inscription nearing the surface, observations that were also corroborated by its distinct guiding characteristics when compared to the adoption of post writing wet etching. The spectral analysis (in the 500-1700 nm range) also evidenced an increase in insertion loss for longer wavelengths and smaller surface to core center separations, caused, most likely, by coupling loss due to the interaction between the propagating mode and the surface. Different lengths of waveguide exposed to the surface were also tested, revealing that scattering loss due to surface roughness is not an issue at the centimeter scale.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6