Highly reliable, ultra-wideband, isolator-free quantum-dot mode-locked frequency combs for optical interconnects beyond 3.2Tb/s

TL;DR

This paper presents a highly reliable, ultra-wideband quantum-dot mode-locked frequency comb source operating at 100 GHz spacing, enabling high-throughput optical interconnects beyond 3.2 Tb/s with exceptional stability and longevity.

Contribution

It introduces a novel, compact, and temperature-stable quantum-dot frequency comb source with record bandwidth and reliability, suitable for practical high-speed optical interconnects.

Findings

Operates up to 140°C with stable performance

Achieves 3.328 Tb/s throughput with low power consumption

Demonstrates a mean time to failure of approximately 207 years

Abstract

Quantum dot mode-locked laser-based optical frequency combs are emerging as a critical solution for achieving low-cost, high-efficiency, and large-capacity optical interconnects. The practical implementation of wavelength division multiplexing interconnects necessitates a temperature-stable OFC source with a minimum 100 GHz channel spacing to enable high-bandwidth modulation while mitigating the complexity of optical filtering and detection. By leveraging the advanced co-doping technique and a colliding pulse mode-locking scheme, here, we report a compact, ultra-wideband, highly reliable, isolator-free 100 GHz-spacing InAs/GaAs QD OFC source operating up to a record temperature of 140 {\deg}C. The comb source delivers a record 3 dB optical bandwidth of 14.312 nm, containing flat-top comb lines, each supporting 128 Gb/s PAM-4 modulation, which results in a total throughput of 3.328 Tb/s with an extremely low power consumption of 0.394 pJ/bit at 25{\deg}C. Performance remains stable at 85 {\deg}C, with negligible degradation of device critical metrics. Remarkably, accelerated aging tests under harsh conditions (85 {\deg}C with 8x threshold current injection) revealed a mean time to failure of approximately 207 years. The QD OFC source demonstrated in this work, for the first time, establishes a concrete link between fundamental research on comb sources and their practical deployment in next-generation, high-density optical interconnect systems.