Near normal incidence MUX/DEMUX designs may include an optical demultiplexer coupled to a photonics die, where the optical demultiplexer comprises an input fiber, thin film filters at a first surface of a substrate, a first mirror at the first surface of the substrate, and a second mirror at a second surface of the substrate. The optical demultiplexer may receive an input optical signal comprising a plurality of wavelength optical signals, reflect the input optical signal from the first mirror to the second mirror, reflect the input optical signal from the second mirror to a first of the thin film filters, communicate an optical signal at a first wavelength to the photonics die while reflecting others to the second mirror, reflect the other signals to a second of the plurality of thin film filters, and communicate an optical signal at a second wavelength to the photonics die.