image: Figure | Working principle of the optical neural network chip for OAM mode switching. a, Schematic of the fibre-chip-fibre OAM modes optical switching. DEMUX: Demultiplexer; MUX: Multiplexer. b, Flowchart of the gradient descent algorithm and curve showing the variation of the experimentally measured maximum crosstalk with optimization iteration cycles during the switch from channels 1, 2, and 3 to channels 2, 3, and 1. b, BER versus OSNR curves of QPSK, 8-QAM, and 16-QAM signals at position x4 under two different switching states, along with constellation diagrams at position x4 for switching state 1, switching state 2, and single-channel transmission. (Switching state 1: Input channels 1, 2 and 3 swapped to output channels 2, 3 and 1. Switching state 2: Input channels 1, 2 and 3 swapped to output channels 1, 2 and 3.)
Credit: by Zhengsen Ruan, Yuanjian Wan, Lulu Wang, Wei Zhou, and Jian Wang
The rapid development of technologies such as the Internet, mobile communications, and artificial intelligence has dramatically increased the demand for high-capacity communication systems. Among various solutions, Mode-Division Multiplexing (MDM) has emerged as a crucial technique, utilizing spatial modes like Orbital Angular Momentum (OAM) to enhance communication capacity.
In a recent study, a team of scientists led by Professor Jian Wang from Huazhong University of Science and Technology introduced a flexible mode-switching system based on an optical neural network chip. This system is capable of switching between different OAM modes in a multimode fibre, a critical function for modern optical communication networks. The optical neural network chip provides the necessary flexibility, enabling arbitrary mode switching among the three OAM modes within the fibre.
The system also features an advanced gradient descent algorithm, which ensures that the crosstalk between channels remains below −18.7 dB, thereby maintaining the integrity of the transmitted signals. This was demonstrated experimentally, where different modulation formats were successfully transmitted across various modes.
The introduction of this optical-neural-network-based mode-switching system marks a significant advancement in the field of optical communications, offering a practical solution for multimode fibre networks. The ability to achieve low-crosstalk mode switching paves the way for more efficient and flexible optical networks, capable of meeting the growing demands of modern communication systems.
Journal
Light: Advanced Manufacturing
Article Title
Flexible orbital angular momentum mode switching in multimode fibre using an optical neural network chip