Electro-absorption modulators (EAM) and monolithically integrated electro-absorption modulated lasers (EML) and methods of fabrication are disclosed. Vertically stacked waveguides for a distributed feedback (DFB) laser, an electro-absorption modulator (EAM) and a passive output waveguide are vertically integrated, and the DFB laser, EAM and output waveguide are optically coupled using laterally tapered vertical optical couplers. Laterally tapered vertical optical couplers provide an alternative to conventional butt-coupling of a laser and EAM, offering improved reliability for high power operation over extended lifetimes. The EML may comprise monolithically integrated electronic circuitry, e.g., driver and control electronics for the DFB laser and EAM. Beneficially, integrated EAM driver and control circuitry comprises a high-speed electro-optical control loop for very high-speed linearization and temperature compensation, e.g. to enable advanced modulation schemes, such as PAM-4 and DP-QPSK, for analog optical data center interconnect applications. Some embodiments are compatible with fabrication using a single epitaxial growth.

A method includes forming a laser diode structure including an active layer sandwiched between an n-type contact layer and a p-type contact layer; forming an n-type contact on the n-type contact layer, wherein the n-type contact includes a first noble metal; forming a p-type contact on the p-type contact layer, wherein the p-type contact includes a second noble metal; forming a conductive routing layer on the n-type contact and on the p-type contact, wherein the conductive routing layer is free of noble metals, wherein the conductive routing layer fully covers the n-type contact and the p-type contact; and forming a passivation layer over the conductive routing layer.