140 μm single-polarization passive fully aperiodic large-pitch fibers operating near 2 μm

Dia Darwich (1) , Mostafa Sabra (1) , Rémi Du Jeu (1, 2) , Marie-Alicia Malleville (1, 3) , Romain Dauliat (1) , Raphaël Jamier (1) , Aurélien Benoit (1) , Kay Schuster (4) , Philippe Roy (1)

1 XLIM-PHOT - Photonique Fibre et Sources Cohérentes
2 TOSA - Thales Optronique S.A.
3 Eolite Systems
4 Leibniz IPHT - Leibniz Institute of Photonic Technology

In this paper, we demonstrate a single-polarization feature out of passive very-large-mode-area fully aperiodic large-pitch fibers. It has been previously shown theoretically that one of the two polarizations of the fundamental mode is selectively coupled to a cladding mode. This coupling does not require fiber bending, which permits us to avoid any decrease in mode effective area. The coupling is achieved owing to boron-doped silica inclusions implemented into the microstructured cladding and acting as stress-applying parts. This mechanism has been assessed experimentally in this work using fibers of two different core diameters: 60 μm and 140 μm, providing mode field areas of 3637  μm2 and 14,590  μm2, respectively, at 1942 nm. The tested fibers have a length of 45 cm and an outer diameter exceeding 1 mm, yielding rod-type fibers. Each sample has been characterized using an unpolarized laser source emitting at 1942 nm. This laser, based on a thulium-doped large-mode-area step-index fiber, has a spectral bandwidth of about 0.5 nm. After passing through a piece of the passive fiber, a polarization extinction ratio higher than 16 dB has been achieved.

Domaines: Optique [physics.optics]

Dia Darwich, Mostafa Sabra, Rémi Du Jeu, Marie-Alicia Malleville, Romain Dauliat, et al.. 140 μm single-polarization passive fully aperiodic large-pitch fibers operating near 2 μm. Applied optics, 2017, 56 (33), pp.9221-9224. ⟨10.1364/AO.56.009221⟩. ⟨hal-01644724⟩