# High-Speed GaN-Based Superluminescent Diode for 4.57 Gbps Visible Light Communication
## 5 Conclusions  
In this work, a 442 nm SLD is fabricated with a 8.3\({}^{\circ}\) tilted angle on its front facet. A high-speed blue SLD-based VLC system is demonstrated with a record transmission rate of 4.57 Gbps and a BER of 3.5 \(\times\) 10\({}^{-3}\), which is below the FEC BER limit of 3.8 \(\times\) 10\({}^{-3}\). The modulation bandwidth is 1.35 GHz. Adaptive bit-loading DMT is an efficient modulation scheme. Our work suggests that GaN-based SLD is a promising transmitter to build high data rate, high-speed VLC systems, benefiting from the large modulation bandwidth, with the possibility of enabling other functionalities, including simultaneous lighting and sensing.  
**Author Contributions:** Device testing, data analysis and writing the manuscript: [PERSON]; modulation algorithm: F.H.; device fabrication: J.W., C.M. and S.W.; VLC testing: Y.H., J.H., S.Y. and Y.M.; writing-review and editing: [PERSON], J.Z., Z.L. and L.X.; supervision and review: N.C. and C.S. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research is partially funded by the Natural Science Foundation of China Project, grant number 61925104, 62031011; Natural Science Foundation of Shanghai, grant number 21 ZR1406200; Peng Cheng Laboratory project, grant number PCL2021A14; Fudan University-CIOMP Joint Fund; The joint project of China Mobile Research Institute & X-NET.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Data is available upon request.  
**Acknowledgments:** The authors thank [PERSON] from Jiangsu Institute of Advanced Semiconductors and the characterization &test facilities at Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), CAS for the assistance in FIB milling.  
**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Year** & **Wavelength** & **Substrate** & **Spectral** & **Modulation** & **Data Rate** & **Modulation** & **Ref** \\  & & & **FWHM** & **Bandwidth** & **Scheme** & **Ref** \\ \hline
2016 & 405 nm & Semipolar GaN & 9 nm & 807 MHz (\(-\)3 dB) & 1.3 Gbps & OOK & [12] \\
2018 & 442 nm & c-GaN & 6.5 nm & 405 MHz (\(-\)3 dB) & 1.45 Gbps & NRZ-OOK & [5] \\
2019 & 442 nm & c-GaN & 7 nm & 1 GHz (\(-\)3 dB) & - & - & [16] \\
2019 & 443 nm & c-GaN & 5.1 nm & - & 3.4 Gbps & DMT & [9] \\
2019 & 416 nm & Transparent GaN & 6 nm & - & - & - & [17] \\
2020 & 443 nm & c-GaN & 4.3 nm & 750 MHz & 3.8 Gbps & DMT & [13] \\
2020 & 428 nm & m-GaN & 3 nm & 2.5 GHz (\(-\)3 dB) & - & - & [14] \\
2020 & 442 nm & c-GaN & 4 nm & 600 MHz & 2.95 Gbps & MAPNN-CAP & [15] \\
**2021** & **442 nm** & **c-GaN** & **12 nm** & **1.35 GHz** & **4.57 Gbps** & **DMT** & **This work** \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of GaN-based SLDs for VLC applications.