An apparatus for use in an optical transceiver module that incorporates an integrated multiplexer/demultiplexer for high speed data transfer applications. One example embodiment includes a transmissive block arranged to interface with a transmit optical port, a receive optical port, and a plurality of optical subassemblies. The transmit optical port may transmit a first multiplexed optical signal and the receive optical port may receive a second multiplexed optical signal. Filters may be positioned between the transmissive block and one or more of the optical subassemblies to transmit signals at predetermined wavelengths while reflecting other signals incident thereon.