The AE 7100 series was designed as a laboratory high performance computer controlled fiber optic physical layer simulator for use in Long haul, Enterprise and Metro optical network access testing applications. The AE 7100 is used in the design, analysis, conformance & performance testing of DWDM optical components, systems and specialized optical test equipment.

The effect of fiber physical impairments on DWDM systems can be tested, using a generic Bit Error Rate Test (BERT) system with a flexible fiber optic network physical simulator. The problem of setting up wavelength-specific channels, or lightpaths, in CWDM and DWDM systems is often called the routing and wavelength assignment (RWA) problem. In general, this problem has been studied under the assumption of an ideal physical layer. However, the network transmission performance is highly limited by the physical-layer impairments. When a channel is set up for a given link connection, impairments will be added at each fiber segment and each wavelength-routing node (WRN) to deteriorate the optical signal. The noise at the WRN mainly includes the ASE noise and switch crosstalk, while the impairments in the fiber include attenuation and dispersion effects as well as non-linear effects, such as Four Wave Mixing (FWM). These effects become increasingly more significant as the number of channels and optical pulse rate on a link increases, and of course the length of the fiber. This is a particular challenge for re-use of “old” dark fiber in the 1550 nm band which were designed for use in the 1310 nm band. This application note outlines an approach to testing using a generic test bed consisting of a Spirent AX 4000 Traffic Generator and BER Analyzer, equipped with OC-xxx (e.g. OC-192 or OC-48) interface cards and an AE 7000 series Optical Network Physical Layer Simulator.