  In this paper, we experimentally demonstrate that a silicon dual-drive
Mach-Zehnder modulator (DD-MZM) has great potential for next-generation data
center interconnections (DCIs). For intra-data center interconnections, 120
Gb/s Nyquist 4-ary pulse amplitude modulation (PAM-4) signal is successfully
generated with a silicon DD-MZM operating at C-band and transmitted over 2 km
standard single-mode fiber (SSMF) with a bit error rate (BER) of 5.55x10-4. For
inter-data center interconnections, single sideband (SSB) modulation is chosen
to avoid power fading caused by fiber chromatic dispersion and square-law
detection. We report the generation and transmission of 112 Gb/s Nyquist SSB
PAM-4 signal by using the same silicon DD-MZM and Kramers-Kronig (KK) direct
detection. A two-tap digital post filter and maximum likelihood sequence
detection (MLSD) are applied to compensate for the limited system bandwidth.
After 80 km SSMF transmission, the BER is 2.46x10-3 that is below the 7% HD-FEC
threshold of 3.8x10-3. To the best of our knowledge, our work reports the
highest single-lane bitrate of 80 km SSB transmission based on a silicon
DD-MZM. Our study also shows the feasibility of silicon photonic modulator for
DCI applications in the future.
