Liekki Application Designer v3.0 from Liekki (Way Gambrills, MD) is a simulation and design software environment for fiber lasers and amplifiers with new transient analysis capability. Liekki’s v3.0 provide the ability to simulate the dynamic regime and transients of active components, as well as 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 also offers an improved user interface and reporting tools.