In this talk, I will introduce optimized non-overlapping Schwarz domain decomposition methods for wave equations in the harmonic regime. The construction of the algorithms will be explained in details as well as their convergence properties. An important point concerning the efficiency of these methods is related to the construction of transmitting boundary conditions between the subdomains. To this end, a review of existing boundary conditions and new conditions will be proposed. Finally, numerical simulations will illustrate the behavior of the domain decomposition methods for acoustic (Helmholtz) and electromagnetic (Maxwell) equations.