# Self-aligned connection between two single mode fibers with a near infrared photopolymerization process

Nessim Jebali, Céline Molinaro, Julien Roul, Julie Jermann, Jean Baptiste

Doucet, Benjamin Reig, Olivier Soppera, Véronique Bardinal

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Nessim Jebali, Céline Molinaro, Julien Roul, Julie Jermann, Jean Baptiste Doucet, et al. Self-aligned connection between two single mode fibers with a near infrared photopolymerization process. Journées Nationales des Technologies Emergentes JNTE 2024, Télécom Saint Etienne, Nov 2024, Saint Etienne (FR), France. hal-04974323

HAL Id: hal-04974323

https://laas.hal.science/hal-04974323v1

Submitted on 3 Mar 2025

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Self-aligned connection between two single mode fibers with a near infrared
photopolymerization process

Nessim Jebaliª, Céline Molinaroᵇ,ᶜ, Julien Roulª, Julie Jermannᵇ,ᶜ,
Jean-Baptiste Doucetª, Benjamin Reigª, Olivier Sopperaᵇ,ᶜ and Véronique Bardinalª

ª Université de Toulouse, CNRS, 7 Avenue du Colonel Roche, 31400 Toulouse, France

ᵇ Université de Haute-Alsace, CNRS, IS2M UMR 7361, F-68100 Mulhouse, France

ᶜ Université de Strasbourg, F-67081 Strasbourg, France

Connecting optical fibers to each other or VCSELs (vertical-cavity surface-emitting lasers) to optical fibers is an important step in the development of high-speed optical data communication and compact optical instrumentation systems. However, coupling tolerances on lateral misalignments are tight, particularly in the case of single-mode fibers or devices. Many techniques based on either active [1] or passive alignment [2] were proposed to solve this issue, but most of them are time consuming or costly. A simple alternative is to create a self-written waveguide (SWW). The principle of SWW approach consists in inserting a photosensitive material between the optical parts to be coupled and in exposing it to a laser beam emitted from both facets in order to build a self-aligned, light-induced optical link [3]. In this work, we developed a specific SWW process that is easily applicable to VCSEL-to-fiber coupling as the writing wavelength is in the near infrared range (850 nm) and thus directly matched to the mode to be transmitted. First results obtained on 780 HP fiber-to-fiber connection show a coupling efficiency as high as 82% for a distance of 300 µm, to be compared to only 18 % in the air and 33% in an index matching layer [4]. Moreover, this value remains higher than 60 % for distances up to 500 µm, demonstrating that an efficient waveguide is effectively created.

References :

[1] M. Grabherr, M. Zorn, and Lin R. Borowski "Advanced single-mode VCSEL fiber pigtail", Proc. SPIE 12904, Vertical-Cavity Surface-Emitting Lasers XXVIII, **129040C** (13 March 2024).

[2] P. Maier, et al., "3D-printed facet-attached optical elements for connecting VCSEL and photodiodes to fiber arrays and multi-core fibers", Optics Express, **Vol. 30**, No. 26, December 19, 2022

[3] S.J. Frisken. "Light-induced optical waveguide uptapers." Optics Letters **18.13** (1993): 1035-1037

[4] N. Jebali, et al. "NIR photopolymerization self-writing process for fiber-to-fiber single mode coupling." Proc. SPIE 13002, Semiconductor Lasers and Laser Dynamics XI. Vol. **130020I** (20 June 2024).