Two‐Photon Direct Laser Writing of Inverse‐Designed Free‐Form Near‐Infrared Polarization Beamsplitter

Abstract This paper presents an inverse‐designed 3D‐printed polymer‐based broadband free‐form polarization beamsplitter in the near‐infrared. A computational inverse‐design method is used to design a thin free‐form meta‐grating to split normally incident light with different polarizations to different diffraction orders, one toward the left first order and one toward the right first order. The grating is 3D‐printed using two‐photon direct laser writing. Polarization splitting behavior is experimentally observed in the near‐infrared region for wavelengths of 1.3 and 1.55 µm, and with performance metrics close to the simulation values. The proposed platform combining inverse‐design and 3D‐printing can be extended to the design, fabrication, and integration of multiple broadband photonic structures to build devices with complex functionalities.