Traveling-Wave Electroabsorption Modulated Laser Based on Identical Epitaxial Layer Scheme and HSQ Planarization

Electroabsorption modulated lasers (EMLs), comprising a distributed feedback (DFB) laser and electroabsorption modulator (EAM) monolithically integrated into the same chip, are attractive because of their compact size, low fabrication cost, and their capability to offer a high modulation speed with low drive voltage, low chirp, and high extinction ratio [1] , [2] . The modulation speed of the EML is limited by the RC constant of the EAM electrode, which is conventionally configured with either a lumped or travelling-wave (TW) electrode. The latter approach overcomes the RC limit by including the EAM in a microwave circuit matched to the source [3] . However, due to restrictions imposed by size and materials, TW EAMs have to date been integrated externally using a specifically designed material structure or monolithically using selective area growth.