Polarization Properties of Solid-Core Photonic Crystal Fibers for 1550 nm

Due to its microstructure, photonic crystal fibers present wavelength regions with polarization-dependent loss, an aspect not observed in conventional fibers. We include this fact in their polarization characterization. In this research, the use of polarimetric methods to two different types of large-mode-area microstructured fibers has shown that both samples exhibited elliptical birefringence with residual torsion. We present the modifications required to perform the evaluation and justify its theoretical bases.

Comparison of Fiber-to-Waveguide Couplers in Point Diffraction Interferometer Based on Waveguide Reference Wavefront Source

To improve the power of reference wavefront generated by reference wavefront source (RWS) based on silicon nitride (SiN) waveguide in point diffraction interferometer (PDI), we design the Y-branch coupler and grating coupler, and then compare the maximum coupling efficiency, 3 dB fabrication tolerance, 3 dB alignment tolerance and polarization dependent loss of two couplers. Our results show that grating coupler has higher coupling efficiency, lower etching difficulty and alignment difficulty, while Y-branch coupler has lower coating difficulty. To get the maximum efficiency, mode in the fiber must be TE mode no matter for grating coupler or Y-branch coupler. This paper improves the power of the wavefront by selecting appropriate fiber-to-waveguide couplers for waveguide RWS. PDI based on the power improved waveguide RWS is expected to be used in many measurement fields.