Three-dimensional on-chip mode converter

The implementation of transverse mode, polarization, fre-quency, and other degrees of freedom (d.o.f.s) of photons is an important way to improve the capability of photonic cir-cuits. Here, a three-dimensional (3D) linear polarized (LP) LP11 mode converter was designed and fabricated using a femtosecond laser direct writing (FsLDW) technique. The converter included multi-mode waveguides, symmetric Y splitters, and phase delaying waveguides, which were con-structed as different numbers and arrangements of circular cross section waveguides. Finally, the modes (LP11a and LP11b) were generated on-chip with a relatively low insertion loss (IL). The mode converter lays a foundation for on-chip high-order mode generation and conversion between differ-ent modes, and will play a significant role in mode coding and decoding of 3D photonic circuits.(c) 2023 Optica Publish-ing Group

Automated summary

The implementation of a three-dimensional linear polarized LP11 mode converter using a femtosecond laser direct writing technique is a significant method to improve the capability of photonic circuits. The converter includes multi-mode waveguides, symmetric Y splitters, and phase delaying waveguides. The on-chip generation of LP11a and LP11b modes with relatively low insertion loss provides a foundation for high-order mode generation and mode conversion in 3D photonic circuits, playing a crucial role in mode coding and decoding.