High-channel-count 20 GHz passively mode-locked quantum dot laser directly grown on Si with 41 Tbit/s transmission capacity

Abstract

Low cost, small footprint, highly efficient and mass producible on-chip\nwavelength-division-multiplexing (WDM) light sources are key components in\nfuture silicon electronic and photonic integrated circuits (EPICs) which can\nfulfill the rapidly increasing bandwidth and lower energy per bit requirements.\nWe present here, for the first time, a low noise high-channel-count 20 GHz\npassively mode-locked quantum dot laser grown on complementary\nmetal-oxide-semiconductor compatible on-axis (001) silicon substrate. The laser\ndemonstrates a wide mode-locking regime in the O-band. A record low timing\njitter value of 82.7 fs (4 - 80 MHz) and a narrow RF 3-dB linewidth of 1.8 kHz\nare measured. The 3 dB optical bandwidth of the comb is 6.1 nm (containing 58\nlines, with 80 lines within the 10 dB bandwidth). The integrated average\nrelative intensity noise values of the whole spectrum and a single wavelength\nchannel are - 152 dB/Hz and - 133 dB/Hz in the frequency range from 10 MHz to\n10 GHz, respectively. Utilizing 64 channels, an aggregate total transmission\ncapacity of 4.1 terabits per second is realized by employing a 32 Gbaud Nyquist\nfour-level pulse amplitude modulation format. The demonstrated performance\nmakes the laser a compelling on-chip WDM source for multi-terabit/s optical\ninterconnects in future large-scale silicon EPICs.\n