Design of 4-Channel 25 Gbaud/s PAM-4 Optical Transmitter Module for Short Reach Applications

A 4-channel 850nm VCSEL array optical transmitter module for 50 Gb/s PAM-4 transmission applications was proposed and demonstrated without digital signal processing (DSP). The proposed module was separately measured by 25 Gb/s NRZ and 25GBaud PAM-4 transmissions over 100-meter OM4 multi-mode fiber (MMF). For 25 Gb/s NRZ transmission, the module can be achieved the error-free (BER <; 1.0E-12) transmission under test with the forward error correction (FEC). Also, the clear eye diagrams can be measured for 50 Gb/s PAM-4 transmissions. Therefore, the 4-channel 850 nm VCSEL transmitter module was verified to suitable for 200GBASE-SR4 applications and beyond.