  Low cost, small footprint, highly efficient and mass producible on-chip
wavelength-division-multiplexing (WDM) light sources are key components in
future silicon electronic and photonic integrated circuits (EPICs) which can
fulfill the rapidly increasing bandwidth and lower energy per bit requirements.
We present here, for the first time, a low noise high-channel-count 20 GHz
passively mode-locked quantum dot laser grown on complementary
metal-oxide-semiconductor compatible on-axis (001) silicon substrate. The laser
demonstrates a wide mode-locking regime in the O-band. A record low timing
jitter value of 82.7 fs (4 - 80 MHz) and a narrow RF 3-dB linewidth of 1.8 kHz
are measured. The 3 dB optical bandwidth of the comb is 6.1 nm (containing 58
lines, with 80 lines within the 10 dB bandwidth). The integrated average
relative intensity noise values of the whole spectrum and a single wavelength
channel are - 152 dB/Hz and - 133 dB/Hz in the frequency range from 10 MHz to
10 GHz, respectively. Utilizing 64 channels, an aggregate total transmission
capacity of 4.1 terabits per second is realized by employing a 32 Gbaud Nyquist
four-level pulse amplitude modulation format. The demonstrated performance
makes the laser a compelling on-chip WDM source for multi-terabit/s optical
interconnects in future large-scale silicon EPICs.

Optics;Applied Physics