An optical attenuator can be used in series with the device under test (DUT). An optical transport network (OTN) is a digital wrapper that encapsulates frames of data, to allow multiple data sources to be sent on the same channel. The company offers innovative solutions for the development, installation, management and. Structured modules from fiber basics to 400G coherent. In-depth coverage of DWDM, OTN, coherent optics, network design, and more — written by field engineers.