Micro‐Optics 3D Printed via Multi‐Photon Laser Lithography

Abstract The field of 3D micro‐optics is rapidly expanding, and essential advances in femtosecond laser direct‐write 3D multi‐photon lithography (MPL, also known as two‐photon or multi‐photon polymerization) are being made. Micro‐optics realized via MPL emerged a decade ago and the field has exploded during the last five years. Impressive findings have revealed its potential for beam shaping, advanced imaging, optical sensing, integrated photonic circuits, and much more. This is supported by a game‐changing and increasing industrial interest from key established companies in this field. In this review, the origin and the advancement of micro‐optics fabrication with MPL are detailed by describing the chronology, distinguishing discrete application groups, providing generalized technical data on the processes and available materials, and discussing the foreseen near‐future advances.