Multi-wavelength 128 Gbit s⁻¹ λ ⁻¹ PAM4 optical transmission enabled by a 100 GHz quantum dot mode-locked optical frequency comb

Abstract

Semiconductor mode-locked lasers (MLLs) with extremely high repetition rates are promising optical frequency comb (OFC) sources for their usage as compact, high-efficiency, and low-cost light sources in high-speed dense wavelength-division multiplexing (DWDM) transmissions. The fully exploited conventional C- and L- bands require the research on O-band to fulfil the transmission capacity of the current photonic networks. In this work, we present a passive two-section InAs/InGaAs quantum-dot (QD) MLL-based OFC with a fundamental repetition rate of ~100 GHz operating at O-band wavelength range. The specially designed device favours the generation of nearly Fourier-transform-limited pulses in the entire test range by only pumping the gain section while with the absorber unbiased. The typical integrated relative intensity noise (RIN) of the whole spectrum and a single tone are -152 dB/Hz and -137 dB/Hz in the range of 100 MHz to 10 GHz, respectively. Back-to-back (B2B) data transmissions for 7 selected tones have been realised by employing a 64 Gbaud four-level pulse amplitude modulation format (PAM-4). The demonstrated performance shows the feasibility of the InAs QD MLLs as a simple structure, easy operation, and low power consumption OFC sources for high-speed fibre-optic communications.

Advances of semiconductor mode-locked laser for optical frequency comb generation

“…In comparison, heterogeneous integration of multiple photonic devices has great advantages of flexibility and relatively mature fabrication process, but can be challenging in large-scale foundry production [72]. Table 1 summarizes some representative research results regarding III-V semiconductor comb sources [73][74][75][76][77][78][79][80][81][82][83]. Both the O-band and C-band III-V semiconductor mode-locked OFCs with high repetition rates and narrow linewidth are demonstrated.…”

“…In order to achieve a larger mode-spacing (≥100 GHz), which is more desirable in the DWDM transmission systems, a short laser cavity is needed. The 100 GHz QD mode-locked OFC sources with 128 Gbit/s/λ PAM-4 transmission ability were also presented by using a similar passive two-section InAs QD MLL but with a short laser cavity of 405 μm [78,84].…”