To accommodate the demand of exponentially increasing global wireless traffic driven by the coming beyond 5G and 6G, wireless communication has stepped into the millimeter wave (MMW) band to exploit large available bandwidth. The future wireless application scenarios require wireless communication systems with high speed, low cost, a small footprint and simple configuration, and the integrated light source-based intensity modulation and direct detection (IM-DD) photonic-wireless system can better meet the demand than the traditional system based on bulky components. In this paper, we experimentally demonstrate a lens-free pulse-amplitude-modulation with four levels (PAM-4) and discrete multi-tone with 16-quadrature amplitude modulation (DMT-16QAM) MMW photonic-wireless transmission system in the W-band using an integrated mode-locked laser (MLL) chip and a mixer-based receiver, which could be applicable for flexible wireless applications. The integrated MLL as an on-chip single light source is used to generate W-band signals and simplify the transmitter. The signal-to-noise ratio of the generated wireless signal is improved by two coherent optical carriers both modulated with data and then beating in the photodiode. In addition, we investigate the IM-DD configuration by employing an envelope detector (ED) to receive the PAM-4 signal for further simplifying the system. The ED-based photonic-wireless system is more suitable for the applications with lower data rate and low cost. For higher data rate, the mixer-based PAM-4/DMT-16QAM systems with up to 31.75 Gbit/s net data rate are more favorable, although the cost is also higher.

中文翻译：

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W波段集成了基于MLL芯片的PAM-4 / DMT-16QAM光子无线链路，可实现灵活的应用

为了适应由超越5G和6G带来的全球无线流量呈指数增长的需求，无线通信已进入毫米波（MMW）频段，以利用较大的可用带宽。未来的无线应用场景要求无线通信系统具有高速，低成本，占用空间小和配置简单的特点，并且集成的基于光源的强度调制和直接检测（IM-DD）光子无线系统可以更好地满足需求。基于庞大组件的传统系统。在本文中，我们实验性地展示了采用集成式四电平（PAM-4）的无透镜脉冲幅度调制和具有16正交幅度调制（DMT-16QAM）的WMW宽带MMW光子无线传输系统的离散多音调锁模激光（MLL）芯片和基于混频器的接收器，可适用于灵活的无线应用。集成的MLL作为片上单个光源用于生成W波段信号并简化发送器。生成的无线信号的信噪比通过两个相干的光载波来改善，这两个光载波都经过数据调制，然后在光电二极管中跳动。此外，我们通过采用包络检波器（ED）来接收PAM-4信号来研究IM-DD配置，以进一步简化系统。基于ED的光子无线系统更适合具有较低数据速率和低成本的应用。对于更高的数据速率，尽管成本也更高，但具有高达31.75 Gbit / s净数据速率的基于混合器的PAM-4 / DMT-16QAM系统更为有利。