Ultralow birefringent glass waveguide fabricated by femtosecond laser direct writing

Optical waveguides prepared by femtosecond laser direct writing have birefringent properties, which can affect polarization encoding and entanglement on chips. Here, we first propose a shape-stress dual compensation fabrication scheme to decrease birefringence. Ultralow birefringent waveguides (1 x 10(-9)) were obtained by controlling the cross sectional shape of the main waveguide and adjusting the position of the auxiliary lines. In addition, we prepared polarization-independent directional coupler and demonstrated the evolution of polarization-independent waveguide array with different polarized light. In the future, ultralow birefringent waveguides will be widely applied in polariza-tion encoding and entangled quantum photonic integrated circuits. (c) 2023 Optica Publishing Group

Automated summary

Optical waveguides prepared by femtosecond laser direct writing have birefringent properties, which can affect polarization encoding and entanglement on chips. In this study, we propose a shape-stress dual compensation fabrication scheme to decrease birefringence and obtained ultralow birefringent waveguides (1 x 10(-9)) by controlling the shape and position of the waveguide. We also demonstrate the evolution of polarization-independent waveguide array with different polarized light and suggest that ultralow birefringent waveguides will have extensive applications in polarization encoding and entangled quantum photonic integrated circuits.