Mordern broadband DWDM (dense wavelength-division multiplexing) transmission systems can carry over 100 signal channels on a single fiber. Raman amplifiers are ideally suited for compensating fiber loss in such broadband systems. These amplifiers employ multiple pump lasers, operating at different frequencies. The powers of these pumps need to be controlled dynamically, depending on the actual channel load. The design and testing of these sophisticated control algorithms require an understanding of complex system dynamics that involves time-dependent interactions of many components, via large scale experimentation that is often infeasible on hardware platforms.
PET FROG is a simulation environment for testing power control in optical line systems. Simulation is driven by discrete system events coupled to continuous mathematical representations of the device physics. The simulator models, with detailed time synchronization, signal and noise propagation along a line system consisting of multiple independently controlled transmission elements and monitoring devices, in response to events such as channel add/drops, component failures and recoveries, and message passing. The software supports experimentation in many different modes, and provides logging and visualization of all relevant effects. It serves as a versatile platform for evaluating control algorithms, facilitates systematic exploration of design parameters, and allows assessment of system reliability in various types of events.