We designed and implemented the QSFP28 optical transceiver using PAM4. This study makes the following contributions: (1) 50 Gbps high-capacity long-distance transmission, only PIN-PD was used to minimize circuit complexity and was implemented at low cost over traditional. By combining four-level pulse amplitude modulation (PAM4) with dense wavelength division multiplexing (DWDM) technology, these transceivers enable high-capacity, long-reach optical links up to 80–100 km while maintaining low power consumption and high spectral efficiency. In Proceedings of the 2019 21st International Conference on Advanded Communication Technology (ICACT), PyeongChang, Korea, 17–20 February 2019. These authors contributed equally to this work. Juniper Networks transceivers are hot-removable and hot-insertable field-replaceable units (FRUs). You can remove and replace them without powering off your device or disrupting device. Page 2 Preface Audience: This installation note provides instructions for installing FS Quad Small Form-factor Pluggable 28 (QSFP28) and Small Form-factor Pluggable Double Density (SFP-DD) transceiver modules. These modules are hot- swappable input/output (I/O) devices that plug into 100GBASE. In this evolving landscape, QSFP28 PAM4 DWDM (Dense Wavelength Division Multiplexing) emerges as a practical and high-performance solution for extending 100G and 400G signals across metro, campus, and inter-data-center links. The name breaks down simply: “Quad” means four lanes, “SFP” refers to the Small Form-factor Pluggable mechanical standard “28” indicates each lane runs at 28 Gbps.