Toward self-powered and reliable visible light communication using amorphous silicon thin-film solar cells

Abstract

Enhancing robustness and energy efficiency is critical in visible light communication (VLC) to support large-scale data traffic and connectivity of smart devices in the era of fifthgeneration networks. To this end, we demonstrate that amorphous silicon (a-Si) thin-film solar cells with a high light absorption coefficient are particularly useful for simultaneous robust signal detection and efficient energy harvesting under the condition of weak light in this study. Moreover, a first-generation prototype called AquaE-lite is developed that consists of an a-Si thin-film solar panel and receiver circuits, which can detect weak light as low as 1 µW/cm 2. Using AquaE-lite and a white-light laser, orthogonal frequency-division multiplexing signals with data rates of 1 Mb/s and 908.2 kb/s are achieved over a 20-m long-distance air channel and 2.4-m turbid outdoor pool water, respectively, under the condition of strong background light. The reliable VLC system based on energy-efficient a-Si thin-film solar cells opens a new pathway for future satellite-air-ground-ocean optical wireless communication to realize connectivity among millions of Internet of Things devices.

A Review on Practical Considerations and Solutions in Underwater Wireless Optical Communication

“…To promote the application of PV cells in practical UWOC scenarios. In the following, we use a white laser with a large divergence angle for simultaneous lighting and optical communication in UWOC [121]. We explore PV cells with large detection areas that are capable of detecting weak light, which can alleviate the alignment issues and lays the foundation for future implementation of long-distance underwater communication.…”

AquaE-lite Hybrid-Solar-Cell Receiver-Modality for Energy-Autonomous Terrestrial and Underwater Internet-of-Things

“…In recent years, solar cells have shown significant potential for use in optical wireless communication (OWC) [5]- [14]. By converting optical signals into electrical signals by relying on the photoconductive effect without any external power, solar cells are energy-saving and more environmentally friendly than conventional PIN diodes, avalanche photodiodes, and photomultiplier tubes.…”

“…In this paper, a fully energy-autonomous hybrid-solar-cell receiver called AquaE-lite is developed and tested in various application scenarios, where this is the first step toward developing selfpowered IoT devices. In this work, we propose and demonstrate the use of a monocrystalline Si solar panel with high PCE for efficient energy harvesting, and a thin-film amorphous Si (a-Si) solar cell with a high light absorption coefficient for low-intensity optical signal detection [5], simultaneously. Compared with the use of only one kind of solar cell for simultaneous energy harvesting and signal detection [5]- [11], the proposed scheme can take full advantage of different types of solar cells to improve the energy harvesting as well as the communication performance of the system.…”

“…In this work, we propose and demonstrate the use of a monocrystalline Si solar panel with high PCE for efficient energy harvesting, and a thin-film amorphous Si (a-Si) solar cell with a high light absorption coefficient for low-intensity optical signal detection [5], simultaneously. Compared with the use of only one kind of solar cell for simultaneous energy harvesting and signal detection [5]- [11], the proposed scheme can take full advantage of different types of solar cells to improve the energy harvesting as well as the communication performance of the system. For energy-autonomous IoT devices, we first propose and demonstrate an automatic control scheme that uses a programmable-gain amplifier (PGA).…”

“…On the transmitter (Tx) side, four-quadrature amplitude modulation (4-QAM) OFDM signals were first sent by an arbitrary waveform generator (AWG) and then superposed onto the white-light laser by a bias-tee (Bias-T) after being transmitted through an amplifier (AMP) and an attenuator (ATT). The parameters of the devices and OFDM signals have been provided in [5]. White-light laser with a bias current of 670 mA was used for simultaneous illumination and communication.…”