Direct Modulation of Electrically Pumped Coupled Microring Lasers

TL;DR

This paper demonstrates that gain-loss contrast in coupled microring lasers can be used to significantly enhance their modulation bandwidth, with experimental and simulation results showing up to 1.63 times improvement.

Contribution

It introduces a novel method of modulating laser frequency response through gain-loss contrast in coupled microring lasers, validated by experiments and simulations.

Findings

Bandwidth improved by up to 1.63 times

Gain-loss contrast as a new degree of freedom

Experimental results match simulation predictions

Abstract

We demonstrate how the presence of gain-loss contrast between two coupled identical resonators can be used as a new degree of freedom to enhance the modulation frequency response of laser diodes. An electrically pumped microring laser system with a bending radius of 50 {\mu}m is fabricated on an InAlGaAs/InP MQW p-i-n structure. The room temperature continuous wave (CW) laser threshold current of the device is 27 mA. By adjusting the ratio between the injection current levels in the two coupled microrings, our experimental results clearly show a bandwidth improvement by up to 1.63 times the fundamental resonant frequency of the individual device. This matches well with our rate equation simulation model.