[Paper Review] Chip-to-chip optical multimode communication with universal mode processors

Bo Wu, Wenkai Zhang+5 more|arXiv (Cornell University)|Jun 20, 2023

Optical Network TechnologiesEngineering1 references3 citations

TL;DR

This paper proposes a reconfigurable, intelligent chip-to-chip optical multimode communication system using a universal mode processor based on a programmable 4×4 Mach-Zehnder interferometer (MZI) network. The system supports dynamic generation and sorting of both quasi-linearly polarized (LP) and orbital angular momentum (OAM) modes, achieving 25 Gbit/s transmission with high resilience to crosstalk and environmental disturbances, demonstrating programmable, universal mode control for scalable multimode optical links.

ABSTRACT

The increasing amount of data exchange requires higher-capacity optical communication links. Mode division multiplexing (MDM) is considered as a promising technology to support the higher data throughput. In an MDM system, the mode generator and sorter are the backbone. However, most of the current schemes lack the programmability and universality, which makes the MDM link susceptible to the mode crosstalk and environmental disturbances. In this paper, we propose an intelligent multimode optical communication link using universal mode processing (generation and sorting) chips. The mode processor consists of a programmable 4*4 Mach Zehnder interferometer (MZI) network and can be intelligently configured to generate or sort both quasi linearly polarized (LP) modes and orbital angular momentum (OAM) modes in any desired routing state. We experimentally establish a chip-to-chip MDM communication system. The mode basis can be freely switched between four LP modes and four OAM modes. We also demonstrate the multimode optical communication capability at a data rate of 25 Gbit/s. The proposed scheme shows significant advantages in terms of universality, intelligence, programmability and resistance to mode crosstalk, environmental disturbances and fabrication errors, demonstrating that the MZI-based reconfigurable mode processor chip has great potential in long-distance chip-to-chip multimode optical communication systems.

Motivation & Objective

• To address the lack of programmability and universality in existing mode division multiplexing (MDM) systems for chip-to-chip optical communication.
• To reduce sensitivity to mode crosstalk, environmental fluctuations, and fabrication imperfections in multimode optical links.
• To develop a reconfigurable, intelligent mode processor capable of dynamically generating and sorting both LP and OAM modes.
• To demonstrate a fully integrated, chip-based MDM communication system with high data rate and robustness.

Proposed method

• The mode processor is implemented as a programmable 4×4 Mach-Zehnder interferometer (MZI) network with tunable phase shifts and variable couplers.
• The MZI network is configured via software to route any input mode to any desired output mode, enabling universal mode processing.
• The system supports switching between four LP modes and four OAM modes by reconfiguring the MZI phase settings.
• The mode processor is integrated into a chip-to-chip optical link, with mode generation and sorting performed on-chip at both transmitter and receiver ends.
• The system uses a digital control interface to dynamically reconfigure the MZI network for different mode bases and routing states.
• The experimental setup validates the system’s ability to maintain low crosstalk and high signal integrity across mode transitions.

Experimental results

Research questions

• RQ1 Can a single, reconfigurable MZI-based processor generate and sort both LP and OAM modes in a programmable manner?
• RQ2 How does the system perform in terms of crosstalk and signal integrity when switching between different mode bases?
• RQ3 To what extent can the processor mitigate the impact of environmental disturbances and fabrication errors on mode fidelity?
• RQ4 What data rate can be achieved with universal mode processing in a chip-to-chip multimode optical link?
• RQ5 How does the system’s programmability enhance scalability and adaptability in future optical interconnects?

Key findings

• The system successfully demonstrated chip-to-chip multimode optical communication at a data rate of 25 Gbit/s with low bit error rate.
• The universal mode processor enabled dynamic switching between four LP modes and four OAM modes without hardware reconfiguration.
• The system exhibited high resilience to mode crosstalk, with minimal signal degradation during mode transitions.
• The MZI-based processor maintained low crosstalk and high signal integrity under environmental and fabrication-induced perturbations.
• The programmable nature of the MZI network allowed for real-time reconfiguration of mode routing, enabling flexible and intelligent multimode operation.
• The results confirm the feasibility of using reconfigurable MZI chips as a universal platform for scalable, high-capacity optical interconnects.