Influence of Residual Facet Reflection on the Eye-Diagram Performance of High-Speed Electroabsorption Modulated Lasers

The influence of residual facet reflection on the small-signal modulation response and the large-signal eye-diagram performance of 40 Gb/s electroabsorption modulated lasers (EMLs) is studied. Measurement and simulation show that the eye-diagram performance is not only limited by the modulation bandwidth of the device, but also significantly degraded by the low frequency resonances in the frequency response due to residual facet reflection. Clear eye-opening has been demonstrated by optimizing the anti-reflection (AR) coating of the EA modulator facet.