High Spectral Efficiency Long-wave Infrared Free-Space Optical Transmission with Multilevel Signals
Journal of Lightwave Technology 2023
Mengyao Han, Mahdieh Joharifar, Muguang Wang, Richard Szhatz, Rafael Puerta, Yan-Ting Sun, Gregory Maisons, Johan Abautret, Roland Teissier, Lu Zhang, Sandis Spolītis, Vjačeslavs Bobrovs, Sebastian Lourdudoss, Xianbin Yu, Sergei Popov, Oskars Ozoliņš, Xiaodan Pang

This study explores the potential of long-wave infrared free-space optical (FSO) transmission that leverages multilevel signals to attain high spectral efficiency. The FSO transmission system consists of a directly modulated-quantum cascade laser (DM-QCL) operating at 9.15 μm and a mercury cadmium telluride (MCT) detector. To fully understand the system, we conduct measurements on the DM-QCL chip and MCT detector and assess the overall amplitude response of the DM-QCL, MCT detector, and all electrical components. We apply various signals, including on-off keying (OOK), 4-level pulse amplitude modulation (PAM4), 6-level PAM (PAM6), and 8-level PAM (PAM8) to maximize the bit rate and spectral efficiency of the FSO transmission. Through a two-dimensional sweeping of the laser bias current and MCT detector photovoltage, we optimize the transmission performance. At the optimal operation point, the FSO system achieved impressive results which are up to 6 Gbaud OOK, 3.5 Gbaud PAM4, 3 Gbaud PAM6, and 2.7 Gbaud PAM8 signal transmissions, with a bit error rate performance below 6.25% overhead hard decision-forward error correction limit when the DM-QCL operates at 10°C. We also evaluate the eye diagrams and stability of the system to showcase its remarkable transmission performance. Our findings suggest that the DM-QCL and MCT detector-based FSO transceivers offer a highly competitive solution for the next generation of optical wireless communication systems.

Atslēgas vārdi
Bit error rate | Detectors | Free-space optical communication | intensity modulation | Laser beams | long-wave infrared | Modulation | quantum cascade laser | Quantum cascade lasers | Spectral efficiency | Wireless communication

Han, M., Joharifar, M., Wang, M., Szhatz, R., Puerta, R., Sun, Y., Maisons, G., Abautret, J., Teissier, R., Zhang, L., Spolītis, S., Bobrovs, V., Lourdudoss, S., Yu, X., Popov, S., Ozoliņš, O., Pang, X. High Spectral Efficiency Long-wave Infrared Free-Space Optical Transmission with Multilevel Signals. Journal of Lightwave Technology, 2023, Vol. 41, No. 20, 6514.-6520.lpp. ISSN 0733-8724. Pieejams: doi:10.1109/JLT.2023.3287934

Publikācijas valoda
English (en)
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