Abstract: An optoelectronic package with direct free space optical communication between pairs of optical transmitters and receivers located on different substrate surfaces in a closely spaced stack of chip carrying substrates is disclosed. The transmitters and receivers are aligned so that a light beam from each transmitter follows an optical path toward its respective receiver. In the stack of substrates, the transmitters and receivers are mounted on the surfaces of the substrates, many of which are separated by intervening substrates. These intervening substrates have vias, holes or transparent regions, or other optical means, at locations along the optical paths connecting the transmitters and receivers. Lenses or other concentrating means, where required, are adjacent to a transmitter so that its diverging light is focused on the intended receiver. Substrates are aligned so that the light from transmitters shines through the optical means in intervening substrates to the receivers.