Two-Step 3D Printed Few-Mode Fiber Mode Power Equalizer

We proposed and demonstrated an all-fiber type few-mode fiber mode power equalizer fabricated using two-photon polymerization (TPP) 3D printing technology, aimed at addressing the key challenge of mode-dependent loss between different modes in mode-division multiplexing (MDM) systems. Differential attenuation between the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{L} \mathrm{P}_{{0 1}}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{LP}_{{11}}$</tex> modes was generated by precisely 3D printing three-layer waveguide structures on the end face of the few-mode fiber, thereby achieving mode power equalization between the modes. The innovative TPP 3D printing technique enables the flexible fabrication of waveguides with multi-layer refractive index profiles, effectively manipulating the attenuation of different modes, which will be particularly useful in few-mode fiber transmission systems.