ESD polarity effect study of monolithic, integrated DFB-EAM EML for 100/400G optical networks

We study the polarity effect of electrostatic discharge (ESD) of the integrated electro-absorption modulated laser (EML) devices for 100/400G applications. We show that the ESD of integrated EML exhibits stronger polarity dependence compared to the discrete laser diode or planar photodiode devices, likely related to the interface state. The ESD polarity ratio of forward vs. reverse bias is 32.5 for the EML, more asymmetrical compared to the planar devices where the ESD polarity ratio is in the range of 3.0-5.5. Physical model is developed to account for the ESD polarity effect. The chip-level characterization of ESD polarity is important for the design of the module package that can provide additional ESD improvement with impedance matching. With the matching resistor in the module, the reverse ESD threshold can be improved by a factor of 5.