Application Designer v3.0 from Liekki (Lohja, Finland) is a simulation and design software environment for fiber lasers and amplifiers with new transient analysis capability. The software provides the ability to simulate the dynamic regime and transients of active components and new components such as time-dependent signal sources and optical modulators. The new software upgrade also includes the ability to calculate non-linear effect thresholds such as Brillouin scattering and Raman scattering, and the effect of refractive index variation with optical power density. The software suite also offers an improved user interface and reporting tools.