Mapping Twisted Light into and out of a Photonic Chip

TL;DR

This paper demonstrates the first integrated photonic chip capable of supporting and faithfully transmitting twisted light with orbital angular momentum, enabling high-capacity classical and quantum information processing.

Contribution

It introduces a laser-direct-written waveguide supporting OAM modes and experimentally shows efficient, low-crosstalk transmission of twisted light states through a photonic chip.

Findings

Supports OAM modes with up to 60% efficiency

Faithful mapping of twisted light into and out of the chip

Transmission of quantum single-photon OAM states

Abstract

Twisted light carrying orbital angular momentum (OAM) provides an additional degree of freedom for modern optics and an emerging resource for both classical and quantum information technologies. Its inherently infinite dimensions can potentially be exploited by using mode multiplexing to enhance data capacity for sustaining the unprecedented growth in big data and internet traffic, and can be encoded to build large-scale quantum computing machines in high-dimensional Hilbert space. While the emission of twisted light from the surface of integrated devices to free space has been widely investigated, the transmission and processing inside a photonic chip remain to be addressed. Here, we present the first laser-direct-written waveguide being capable of supporting OAM modes and experimentally demonstrate a faithful mapping of twisted light into and out of a photonic chip. The states OAM$_{0}$, OAM$_{-1}$, OAM$_{+1}$ and their superpositions can transmit through the photonic chip with a total efficiency up to 60% with minimal crosstalk. In addition, we present the transmission of quantum twisted light states of single photons and measure the output states with single-photon imaging. Our results may add OAM as a new degree of freedom to be transmitted and manipulated in a photonic chip for high-capacity communication and high-dimensional quantum information processing.