High-speed hybrid circuit

An optoelectronic module, comprising:

• a printed circuit board including a core layer and a first cap layer affixed to a surface of the core layer, wherein the first cap layer comprises a material having a relative permittivity and a loss tangent that are both lower than a material comprising the core layer, the first cap layer defining a top side of the printed circuit board;
• an optical transmitter window formed as a first void on the top side of the printed circuit board;
• an optical receiver window formed as a second void on the top side of the printed circuit board;
• a cavity formed as a third void opposite the first void and the second void on a bottom side of the printed circuit board;
• a heat sink at least partially disposed in the cavity, the heat sink having a first side forming a bottom of the optical transmitter window and a bottom of the optical receiver window;
• an optical transmitter circuit die including at least one transmitter die bond pad electrically coupled to the top side of the printed circuit board, the optical transmitter circuit die mounted to the bottom of the optical transmitter window;
• an optical receiver circuit die including at least one receiver die bond pad electrically coupled to the top side of the printed circuit board, the optical receiver circuit die mounted to the bottom of the optical receiver window;
• and
• a lens mounted to the heat sink.