In this experiment, we generate PAM4 signals based on a dual-polarization Mach-Zehnder modulator (DP-MZM) without DAC. Two high-speed binary OOK signals with different driving voltages are used to modulate a DP-MZM. After modulation, the intensity of the optical OOK signal in a polarization state is 0.7 times of the other. In this way, up to 200-Gbit/s PAM4 signals can be successfully generated. We also measure the BER performance of the generated PAM4 signals after 1-km dispersion shifting fiber (DSF) transmission. Based on the experimental results, the generated 160-Gbit/s PAM4 signal can be successfully transmitted over 1-km DSF, satisfying the hard-decision forward error correction (HD-FEC) threshold of $3.8\times 10 ^{\mathbf {-3}}$ . Moreover, the system can support up to 200-Gbit/s PAM4 signal transmission over 1-km DSF when satisfying the soft-decision forward error correction (SD-FEC) threshold of $2\times 10 ^{\mathbf {-2}}$ .

中文翻译：

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通过不带 DAC 的双极化 Mach-Zehnder 调制器生成 200-Gbit/s PAM4

在本实验中，我们基于没有 DAC 的双极化 Mach-Zehnder 调制器 (DP-MZM) 生成 PAM4 信号。两个具有不同驱动电压的高速二进制 OOK 信号用于调制 DP-MZM。调制后的偏振态光OOK信号的强度是另一个的0.7倍。通过这种方式，可以成功生成高达 200-Gbit/s 的 PAM4 信号。我们还测量了 1 公里色散位移光纤 (DSF) 传输后生成的 PAM4 信号的 BER 性能。根据实验结果，生成的 160-Gbit/s PAM4 信号可以在 1-km DSF 上成功传输，满足硬判决前向纠错 (HD-FEC) 阈值 $3.8\times 10 ^{\mathbf {-3}}$ . 此外，当满足以下软判决前向纠错（SD-FEC）阈值时，系统可以支持高达 200-Gbit/s PAM4 信号在 1-km DSF 上传输。 $2\times 10 ^{\mathbf {-2}}$ .