Bi-LSTM-Augmented Deep Neural Network for Multi-Gbps VCSEL-Based Visible Light Communication Link

Abstract

With the remarkable advances in vertical-cavity surface-emitting lasers (VCSELs) in recent decades, VCSELs have been considered promising light sources in the field of optical wireless communications. However, off-the-shelf VCSELs still have a limited modulation bandwidth to meet the multi-Gb/s data rate requirements imposed on the next-generation wireless communication system. Recently, employing machine learning (ML) techniques as a method to tackle such issues has been intriguing for researchers in wireless communication. In this work, through a systematic analysis, it is shown that the ML technique is also very effective in VCSEL-based visible light communication. Using a commercial VCSEL and bidirectional long short-term memory (Bi-LSTM)-based ML scheme, a high-speed visible light communication (VLC) link with a data rate of 13.5 Gbps is demonstrated, which is the fastest single channel result from a cost-effective, off-the-shelf VCSEL device, to the best of the authors’ knowledge.

End-to-End Learning for VCSEL-Based Optical Interconnects: State-of-the-Art, Challenges, and Opportunities

“…Besides FCNNs, CNNs [87], recurrent neural networks (RNNs) [85], [88]- [91], and long short-term memory (LSTM) NNs [92] are also used to improve the equalization performance at the cost of computational complexity and training epochs. However, it is possible to use transfer learning to use the knowledge gained from NNs trained for equalization with FCNN and train an RNN with a reduced number of epochs [91].…”

Experimental Demonstration of 38 Gbps Over 2.5 m OWC Systems With Eye-Safe 850 nm SM-VCSELs

“…Due to their vertical emission and ease of fabrication, VC-SELs can be monolithically integrated into two-dimensional (2D) arrays for spatial diversity and multiple-input multipleoutput (MIMO) OWC systems. Experimental works on gigabit OWC were implemented with individual VCSEL sources at wavelengths of 650 nm [6], 850 nm [7], and 1310 nm [8] with data rates of up to 25 Gbps.…”