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

Shujie Pan,Mingchen Guo,Zihao Wang,Jie Yan,Peter M Smowton,Lei Wang,Siming Chen,Mengya Liao,Alwyn Seeds,Dingyi Wu,Xi Xiao,Hongguang Zhang,Ting Wang,Zizhuo Liu,Mingchu Tang,Huiyun Liu,Xiao Hu

doi:10.1088/1361-6463/ac4365

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 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 of the whole spectrum and a single tone are −152 and −137 dB Hz−1 in the range of 100 MHz–10 GHz, respectively. Back-to-back data transmissions for seven selected tones have been realised by employing a 64 Gbaud four-level pulse amplitude modulation format. 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.

Highlights

The optical frequency combs (OFCs) with a straightforward connection between optical and microwave domains are used in numerous fields, such as medical diagnostics [1], atomic clock distribution/recovery [2], precision measurements [3,4,5], gas spectroscopy [6, 7], and optical communications [8,9,10,11,12]
We present a passive two-section InAs/InGaAs quantum-dot (QD) mode-locked lasers (MLLs)-based OFC with a fundamental repetition rate of ∼100 GHz operating at O-band wavelength range
Considering all points listed above, in this work, we report a passively QD MLL-based O-band transform-limited OFC source generated at ∼100 GHz fundamental repetition rate with sub-picosecond pulse durations

Summary

Introduction

The optical frequency combs (OFCs) with a straightforward connection between optical and microwave domains are used in numerous fields, such as medical diagnostics [1], atomic clock distribution/recovery [2], precision measurements [3,4,5], gas spectroscopy [6, 7], and optical communications [8,9,10,11,12] To support such a broad application divergence, the last two decades have witnessed an expansion of the laser-based comb technology [13, 14]. While the MLLs-based OFC sources with a larger mode-spacing (⩾100 GHz) are more desirable in the DWDM transmission systems for the potentially reduced number of light sources required, it is challenging to obtain the needed high gain in an ultimate short cavity, especially for QD materials devices. Our results suggest the proposed two-section QD MLL is a powerful candidate for simple structure, low-cost, high efficiency and integrable DWDM light sources

Material and device design

Methods

Characterisation and discussion

Data transmission experiment and results

Conclusions