800 Gb/s/200 m FSO link with a WDM-PAM4 scheme and SLM-based beam tracking technology
Hai‐Han Lu, Xu-Hong Huang, Wen-Shing Tsai, Chao-Yu Feng, Cing-Ru Chou, Yihao Chen, Yu‐Ting Huang, Agustina Nainggolan
Abstract
An 800 Gb/s/200 m free-space optical (FSO) link with a wavelength-division multiplexing (WDM)-four-level pulse amplitude modulation (PAM4) scheme and spatial light modulator (SLM)-based beam tracking technology is constructed. To the best of our knowledge, this is the first one that adopts a WDM-PAM4 scheme and an SLM-based beam tracking technology to simultaneously afford a high transmission capacity of 800 Gb/s and resolve the laser beam misalignment problem due to target device movement. By adopting a 16-wavelength WDM-PAM4 scheme, the transmission capacity of the FSO link is considerably enhanced with an 800 Gb/s ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>50</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">G</mml:mi> <mml:mi mathvariant="normal">b</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi mathvariant="normal">s</mml:mi> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">P</mml:mi> <mml:mi mathvariant="normal">A</mml:mi> <mml:mi mathvariant="normal">M</mml:mi> <mml:mn>4</mml:mn> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> </mml:mrow> <mml:mi>λ</mml:mi> <mml:mo>×</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>16</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mi>λ</mml:mi> </mml:math> ) total capacity. By deploying an SLM-based beam tracking technology, the laser beam misalignment problem is practically resolved for providing an FSO link with high link accessibility. This demonstrated WDM-PAM4 FSO link fully meets the requirements of high-speed, long-reach, and high-reliability transmissions.