SSBI-Free Direct Detection via Phase Diverse of Residual Optical Carrier Enabled by Finite Extinction Ratio IQ Modulator for Datacenter Interconnections

TL;DR

This paper presents a cost-effective, SSBI-free direct detection method for datacenter interconnections that leverages phase diversity caused by finite-extinction ratio IQ modulators, achieving high data rates over long distances.

Contribution

It introduces a novel approach transforming the finite-ER limitation of IQ modulators into an advantage for SSBI-free detection, eliminating extra hardware and complexity.

Findings

Achieved 400 Gb/s data rate over 100 km SSMF.

Gained 1.78 dB Global-SNR improvement.

Demonstrated cost-effective, low-complexity interconnection solution.

Abstract

Cost-effective, low-complexity and spectrally efficient interconnection can offer fundamental guiding law for future datacenter. In this work, we demonstrate a cost-efficient SSBI-free direct detection for datacenter interconnection, leveraging the phase diversity of residual optical carrier caused by finite-extinction ratio (ER) IQ modulators, combining the device cost-effective IQ modulator with finite-ER and efficient SSBI-free phase-diverse direct detection receiver. Specifically, the proposed solution transforms the inherent limitation of finite-ER of cost-effective IQ modulator into the residual optical carrier advantage of SSBI-free direct detection systems, eliminating SSBI without additional hardware and control complexity. A digital pre-distortion and offset correction algorithms, and a PD-thermal-noise constrained SSBI-free direct detection and signal recovery algorithms are derived and implemented. Comprehensive simulations are conducted. A Global-SNR gain of 1.78 dB and 400 Gb/s data rate are achieved in 100-km SSMF transmission when (ER_i, ER_o)= (7 dB, 25 dB) of IQ modulator. The proposed solution enables low-complexity, cost-effective, and spectrally-efficient interconnects for next-generation datacenters.