3D-printed facet-attached optical elements for beam shaping in optical phased arrays

TL;DR

This paper introduces a novel 3D-printed facet-attached optical element integrated with an optical phased array, enabling precise beam shaping and steering with high accuracy and a wide steering range, using in-situ multi-photon lithography.

Contribution

The work presents a new method for fabricating integrated beam shapers directly onto waveguide facets using high-resolution 3D printing, improving alignment and steering capabilities.

Findings

Achieved a ±30° steering range without grating lobes.

Demonstrated a beam divergence of approximately 2° FWHM.

Validated the approach as a versatile alternative to traditional grating structures.

Abstract

We demonstrate an optical phased-array (OPA) equipped with a 3D-printed facet-attached element for shaping and deflection of the emitted beam. The beam shaper combines freeform refractive surfaces with total-internal-reflection (TIR) mirrors and is in-situ printed to edge-emitting waveguide facets using high-resolution multi-photon lithography, thereby ensuring precise alignment with respect to on-chip waveguide structures. In a proof-of-concept experiment, we achieve a grating-lobe free steering range of $\pm 30{\deg}$ and a full-width-halfmaximum (FWHM) beam divergence of approximately $2{\deg}$. The concept opens an attractive alternative to currently used grating structures and is applicable to a wide range of integration platforms.