A 100-Gb/s PAM4 Optical Transmitter in a 3-D-Integrated SiPh-CMOS Platform Using Segmented MOSCAP Modulators
A 100-Gb/s PAM4 Optical Transmitter in a 3-D-Integrated SiPh-CMOS Platform Using Segmented MOSCAP Modulators
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DOI：
10.1109/jssc.2022.3210906
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发表时间：
2023-01
影响因子：
5.4
通讯作者：
Arian Hashemi Talkhooncheh;Weiwei Zhang;Minwo Wang;D. Thomson;M. Ebert;L. Ke;G. Reed;A. Emami
中科院分区：
文献类型：
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作者：
Arian Hashemi Talkhooncheh;Weiwei Zhang;Minwo Wang;D. Thomson;M. Ebert;L. Ke;G. Reed;A. Emami
本文介绍了一种在三维集成硅光子学CMOS平台上实现的100 Gb/s四电平脉冲幅度调制（PAM 4）光发射机系统。该光子芯片包括推挽分段马赫-曾德尔调制器（MZM）结构，使用高电容（415 fF-1.1 pF），但光学效率（$V_{\pi }L= 0.8\，\，\text {V}\cdot $ cm）的金属氧化物硅电容器（MOSCAP）相位调制器。两对有效长度为170和450 $\mu \text{m}$的U形调制器段由双通道28 nm CMOS驱动器以50 GBd驱动，该驱动器倒装芯片键合到光子芯片。驱动器内核利用数字可控预失真（PD）和电感峰化来实现足够的电光带宽（EOBW）。这些驱动器为使用0.9 V电源和片内串行化器的调制器提供1.2 Vppd摆幅，可生成50 Gb/s数据流。电子芯片消耗240 mW，实现2.4 pJ/bit的能效。整体EOBW，没有任何PD，增加了约56%和48%，分别为170-和450- $\mu \text{m}$段，相比，他们的EOBW测量65-GHz 50- $\Omega $终止探针。光子芯片的光输入功率为+10 dBm，掺铒光纤放大器将输出信号放大11 dB。50 Gb/s非归零（NRZ）光学原始眼图具有4.3 dB消光比（ER）和1.2 dBm的光调制幅度（OMA）。100 Gb/s PAM 4光学原始眼图显示4.3 dB ER和1.4 dBm OMA，经过五抽头前馈均衡（FFE）滤波器后，发射机色散眼图闭合四元数（TDECQ）为1.53 dB。当温度从30 °C升高到90 °C时，在1 V的最佳正向偏置电压下，PAM 4 TDECQ变化53%。
This article presents a 100-Gb/s four-level pulse-amplitude modulation (PAM4) optical transmitter system implemented in a 3-D-integrated silicon photonics-CMOS platform. The photonics chip includes a push–pull segmented Mach–Zehnder modulator (MZM) structure using highly capacitive (415 fF–1.1 pF), yet optically efficient ( $V_{\pi }L= 0.8\,\,\text{V}\cdot $ cm) metal–oxide–silicon capacitor (MOSCAP) phase modulators. Two pairs of U-shaped modulator segments with effective lengths of 170 and 450 $\mu \text{m}$ are driven at 50 GBd by a dual-channel 28-nm CMOS driver, which is flip-chip bonded to the photonics chip. The driver cores utilize digitally controllable pre-distortion (PD) and inductive peaking to achieve sufficient electro-optical bandwidth (EOBW). The drivers deliver 1.2-Vppd swing to modulators using a 0.9-V supply and on-chip serializers that generate 50-Gb/s data streams. The electronics chip consumes 240 mW achieving 2.4-pJ/bit energy efficiency. The overall EOBW, without any PD, is increased by approximately 56% and 48% for the 170- and 450- $\mu \text{m}$ segments, respectively, when compared to their EOBW measured by 65-GHz 50- $\Omega $ terminated probes. The optical input power to the photonics chip is +10 dBm, and an erbium-doped fiber amplifier amplifies output signals by 11 dB. The 50-Gb/s nonreturn to zero (NRZ) optical raw eye diagram exhibits 4.3-dB extinction ratio (ER) and 1.2 dBm of optical modulation amplitude (OMA). The 100-Gb/s PAM4 optical raw eye diagram shows 4.3-dB ER and 1.4-dBm OMA with a transmitter dispersion eye closure quaternary (TDECQ) of 1.53 dB after a five-tap feed-forward-equalization (FFE) filter. The PAM4 TDECQ changes by 53% when the temperature is increased from 30 °C to 90 °C at the optimum forward bias voltage of 1 V.