We study analytically the polarization behaviour of directional couplers composed of birefringent waveguides, showing that they can induce polarization transformations that depend on the specific input-output path considered. On the basis of this study, we propose and demonstrate experimentally, by femtosecond laser writing, directional couplers that yield a polarization-independent power splitting and, at the same time, preserve the polarization state of the propagating light. More in detail, we devise two di erent approaches to realize such devices: the first one is based on local birefringence engineering by additional refractive index modification tracks, while the second one exploits ultra-low birefringence waveguides (b = 1.2 × 10−6), obtained by thermal annealing.

Symmetric polarization-insensitive directional couplers fabricated by femtosecond laser writing

Corrielli, Giacomo;Atzeni, Simone;PIACENTINI, SIMONE;PITSIOS, IOANNIS;Crespi, Andrea;Osellame, Roberto
2018

Abstract

We study analytically the polarization behaviour of directional couplers composed of birefringent waveguides, showing that they can induce polarization transformations that depend on the specific input-output path considered. On the basis of this study, we propose and demonstrate experimentally, by femtosecond laser writing, directional couplers that yield a polarization-independent power splitting and, at the same time, preserve the polarization state of the propagating light. More in detail, we devise two di erent approaches to realize such devices: the first one is based on local birefringence engineering by additional refractive index modification tracks, while the second one exploits ultra-low birefringence waveguides (b = 1.2 × 10−6), obtained by thermal annealing.
Atomic and Molecular Physics, and Optics
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1056597
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