This thesis discusses the routing and wavelength assignment (RWA) problem for the wavelength routed optical networks (WRONs). Firstly, we present an optical network design and evaluation simulator which is specialized in design and evaluation of optical network topology, reconfiguration, restoration, and RWA algorithm. Our simulator is implemented with modularized, platform-independent, and extensible architecture which is light-weight and suitable to verify the simulation results. Next, we propose two novel heuristic RWA algorithms for the static and dynamic traffic models, respectively. The proposed algorithm for the static model evenly distributes and compactly arranges the routing paths over the network according to load balanced scheme, namely minimum loaded path first (MLPF). The MLPF algorithm can increase network throughput and reduce blocking probability. For the dynamic model, we propose dynamic hop count shifting (DYHOS) algorithm which can dynamically adjust hop count of a lightpath according to the volume of the incoming traffic load and blocking ratio in the network. The DYHOS algorithm finds an available route while minimizing the waste of network resources. This algorithm also increases the network throughput and reduces the blocking probability. Through the computer simulation, we verify the performance of proposed algorithms, where the performance is the blocking probability for the given number of wavelength used.