The receiver module. All data signals are differential and support a data rates up to 10.3 G per channel. What’s the difference of these two links? From the viewpoint of optical transceiver module structure, parallel single-mode seems more cost effective because it uses a single uncooled CW laser which splits its output power into four integrated silicon modulators.
Besides, its array-fiber coupling to an MTP connector is relatively simple. From the viewpoint of infrastructure, parallel single mode is more expensive, because when the link distance is long, parallel singlemode uses 8 optical singlemode fibers while coarse wavelength division multiplexing uses only 2 optical singlemode fibers.