An optical transceiver converting and coupling an information-containing electrical signal with an optical fiber including a housing conforming to the industry standard XENPAK.TM. form factor including an electrical connector for coupling with an external electrical cable or information system device and for transmitting and/or receiving an information-containing electrical communications signal, and a fiber optic connector adapted for coupling with an external optical fiber for transmitting and/or receiving an optical communications signal. At least one electro-optical subassembly is provided in the housing for converting between an information-containing electrical signal and a modulated optical signal corresponding to the electrical signal, along with a modular, interchangeable communications protocol processing printed circuit board in the housing for processing the communications signal into a predetermined electrical or optical communications protocol, such as the IEEE 802.3ae 10 Gigabit BASE LX4 physical layer.