Objectives

The overall objective of this proposal is to investigate and demonstrate the use of the orbital angular momentum (OAM) modes of light for communications and networking. Specifically, it has two primary objectives:

Objective 1: Exploiting the use of OAM modes in optical fibres as a disruptive means of increasing optical fibre transmission capacity for short-reach high data density applications.

The achievement of this objective will be demonstrated over a multiplexed transmission testbed utilising OAM multiplexing and wavelength division multiplexing (WDM) dimensions. The target will be a 10x or more capacity increase by employing 10 or more OAM multiplexed channels over a conventional WDM system. Specifically, the combination of 10x OAM states with 16 wavelength channels will provide a total of 160 multiplexed channels. To demonstrate full compatibility with legacy technologies, each channel will transmit amplitude modulation (AM), differential phase shift keying (DPSK), Polarisation Diversity and WDM up to 100 Gb/s, thus demonstrating a total capacity of 16 Tb/s over a distance of 1-2 km, with the use of OAM multiplexing as an additional layer built upon AM, DPSK, Polarisation Diversity and WDM transmission layers, with minimised channel encoding overhead. Fibres with high index contrast and high concentration of germanium oxide doping and/or air core structures will be employed to support OAM modes.

Objective 2: Exploiting the use of OAM domain as a switching resource in conjunctions with the wavelength domain to significantly improve the scalability and the power consumption of the switches in data-centres applications.

A 10x improvement of the scalability of the data-centre switches will be targeted with the study and development of an OAM-based switch fully compatible with the WDM layer. A two-layer switch exploiting 10 modes on the OAM layer and 16 wavelengths on the WDM layer will be developed. At the final stage of the project, a switch exploiting 10 OAM modes and 16 wavelengths as switching domains will be implemented. In order to demonstrate compatibility with the switches currently employed in the data-centres, the switch will be tested with Ethernet signals at 20 Gb/s/OAM/wavelength.

The developed two-layer switch will enable a more than 10x reduction of power consumption/Gb/s with respect to the current commercial switches employed in data-centres.

For what concerns the OAM switch configuration time, 100 ns will be demonstrated, which represents an 8x improvement with respect to commercial switches.

Objectives 1 and 2 will be enabled by integrated high performance OAM components build on silicon photonics technology, thus fully CMOS-compatible.