Quantum cryptography is a new branch of cryptology and physics that relies on the use of protocols designed to exploit quantum mechanical phenomena to achieve the secrecy of cryptographic keys. The purpose of quantum key distribution is for two or more correspondents, who share no secret information initially, to agree on random keys, which remain secret against attacks from more powerful analytic or computational tools. In this thesis, several novel secure optical communication network models are presented. The security of these network models is achieved using quantum cryptographic-key distribution. Both point-to-point and multiple access broadcast networks ore considered. Furthermore, in developing these models, the simplicity, generality find flexibility are highly maintained. Thus, it is possible to use these models efficiently for software simulation purposes. Each secure optical communication network model is assumed to be composed of many communication nodes (stations) that are connected by three types of fiber optic channels. These are the quantum, authenticated public, and timing channels. Errors can occur in quantum transmission due to eavesdropping and system inefficiencies, Thus, an error elimination technique is implemented. In this technique, several rounds of random permutations and block parity comparisons are done between the transmitter and receiver. Then, another strategy of random subset parity comparisons is performed. Blocks or subsets of discordant parities are subjected to a bisective search to find error locations and eliminate them. After all quantum transmission errors are discovered and discarded, an important mathematical technique called privacy amplification is implemented. Using this technique, eavesdropper information about the final cryptographic key is reduced to an arbitrary value smaller than one bit. This essentially is achieved by publicly choosing length-reducing transformations to apply to primary keys so that partial eavesdropper information about inputs conveys almost no knowledge of the outputs. In the designing of secure models for multiple access broadcast networks, both the broadcasting and multicasting quantum transmission modes are enabled. This is done via introducing electro-optic switches in the implementation of quantum channels. Hence, the efficiency of quantum cryptography protocols can significantly be increased, in many situations. All network quantum cryptography protocols are simulated via the object-oriented programming (OOP) approach using the Borland C ++ Compiler Version 4.5. Simulation results for both error elimination and privacy amplification stages are presented. \