# Vector Vortex Beam Emitter Embedded in a Photonic Chip

## TL;DR

This paper reports the first successful embedding of a vector vortex beam emitter within a photonic chip, enabling efficient on-chip generation of complex light modes for advanced optical communication and quantum computing.

## Contribution

It introduces a novel integrated vector vortex beam emitter in a photonic chip using femtosecond laser writing, with detailed mode conversion analysis and high efficiency.

## Key findings

- Achieved up to 30% efficiency in vector vortex beam emission from a chip.
- Demonstrated scalar vortex beam emission with 74% efficiency.
- Provided an expanded coupled-mode model for understanding mode conversion and fabrication effects.

## Abstract

Vector vortex beams simultaneously carrying spin and orbital angular momentum of light promise additional degrees of freedom for modern optics and emerging resources for both classical and quantum information technologies. The inherently infinite dimensions can be exploited to enhance data capacity for sustaining the unprecedented growth in big data and internet traffic, and can be encoded to build quantum computing machines in high-dimensional Hilbert space. So far much progress has been made in the emission of vector vortex beams from a chip surface into free space, however, the generation of vector vortex beams inside a photonic chip hasn't been realized yet. Here, we demonstrate the first vector vortex beam emitter embedded in a photonic chip by using femtosecond laser direct writing. We achieve a conversion of vector vortex beams with an efficiency up to 30% and scalar vortex beams with an efficiency up to 74% from Gaussian beams. We also present an expanded coupled-mode model for understanding the mode conversion and the influence of the imperfection in fabrication. The fashion of embedded generation makes vector vortex beams directly ready for further transmission, manipulation and emission without any additional interconnection. Together with the ability to be integrated as an array, our results may enable vector vortex beams become accessible inside a photonic chip for high-capacity communication and high-dimensional quantum information processing.