Optical MUX/DEMUX assembly

An optical assembly for demultiplexing wavelength channels, the optical assembly comprising:

• an optical port assembly comprising an array of optical ports;
• a retro-reflecting Z-block of optically transmissive material comprising a port facing face and a back face;
• and
• an array of optical filters located along the port facing face in an optical alignment with respective ones of the optical ports, wherein the optical filters are configured to selectively transmit light of corresponding wavelength channels;
• wherein the back face of the retro-reflecting Z-block comprises a main reflective surface between first and second angled reflective surfaces, said first and second angled reflective surfaces together forming a retroreflector for light entering the retro-reflective Z-block via a first optical port of the array of optical ports,
• wherein the retro-reflecting Z-block is configured to direct light entering the retro-reflecting Z-block from the first optical port to each of the optical filters starting with one of the optical filters optically aligned with one of the optical ports at an opposite end of the array of optical ports from the first optical port.