Ultrafast laser direct writing of material independent integrated nonlinear components based on NPE

Material independent integrated nonlinear components (MIINC) based on nonlinear polarization evolution (NPE) play an important role in the emerging quantum computing, integrated photonics and ultrafast science. However, to our knowledge, no one has yet employed ultrafast laser direct writing for NPE-based MIINC. Here, for the first time, we finish the MIINC direct writing based on NPE using an ultrafast laser, and we suggest a multi-slice (MS) approach to in-fiber waveplate direct writing that allows for flexible adjustment of the phase difference, the waveplate fast and slow axis, and the stress birefringence value. To complete the measurement of the nonlinear transmittance curve, a polarization-splitter prism is attached to the output light path's back end. The measurement results agree with the theoretical calculation. MIINC based on NPE with arbitrary nonlinear transmittance curves are fabricated via the direct writing method, which is expected to be used in optical chips in the future.