Methods and systems for CWDM MUX/DEMUX designs for silicon photonics interposers are disclosed and may include an optical transceiver including a silicon photonics interposer, a polarization splitter, a lens array, and a prism with a coarse wavelength division multiplexing (CWDM) coating and a high reflectivity (HR) coating. The polarization splitter, lens array, and prism are coupled to the silicon photonics interposer. An input optical signal of a plurality of different wavelengths and polarizations may be received. Signals of different polarization may be spatially separated using the polarization splitter and signals of a first wavelength range may be reflected into the lens array using the CWDM coating while signals in a second wavelength range may be passed through. Signals of the second wavelength range may be reflected to the lens array using the HR coating, and optical signals may be coupled into the silicon photonics interposer using the lens array.