SiP Ring Resonator Modulator-based Transmitters for Short-Reach Applications

Silicon photonics (SiP) is a key enabling technology for high-symbol rate communication to enable future 800 Gbps and 1.6 Tbps solutions in scalable and energy efficiency way. The 800G pluggable multi-source agreement (MSA) suggests that intensity-modulated direct-detection (IM/DD) is the most sustainable way forward [1]. Recent advances [2–12] in SiP enable dense integration, high yield, and low energy consumption for optical interconnects. Monolithic integration of SiP and complementary metal-oxide semiconductor (CMOS) eliminates need of additional packaging and integration allowing to introduce compact arrayed waveguide grating routers [2] or extremely efficient wavelength division multiplexing filters [3]. All silicon avalanche photodiode [4] has demonstrated $0.73 \mathrm{~A} / \mathrm{W}$, and more than 38 GHz RF bandwidth in O-band operation. To ensure high symbol rate operation high operational bandwidth of each transceiver component is necessary. High-bandwidth SiP slow light modulator [5] and wide free spectral range SiP ring resonator modulator (RRM) [6] have been demonstrated. On-off keying (OOK) at highest symbol rate should be considered thanks to high energy efficiency and simple driving electronics. At expense of more complex driver electronics pulse amplitude modulation with 4 levels also can be considered if the modulator extinction ratio supports it. SiP RRM have unique advantages as low power consumption, small footprint, high scalability, suitability for multichannel operation and easier integration with CMOS drivers and electronics. Recently SiP RRM was used to demonstrate 160 Gbaud OOK [7]. SiP RRM with integrated laser demonstrated 128 Gbaud OOK/PAM4 [8]. Multichannel integration advantages of SiP RRM have been shown by implementing $4 \times 112 \mathrm{Gbps}$ [9], $4 \times 224 \mathrm{Gbps}$ [10] and $16 \times 56 \mathrm{Gbps}$ [11] in O-band as well $32 \times 16 \mathrm{Gbps}$ [12] in C-band. In this paper, we report on several SiP RRM-based transmitters to achieve high symbol rate with performance below 6.7% overhead (OH) hard-decision forward error correction (HD-FEC) threshold of $4.5 \times 10^{-3}$ [13]. We demonstrate on-off keying (OOK) transmission for optical-back-to-back and after transmission over 100 meters of single mode fiber (SMF). RRMs are characterized with [14].