Currently the world is experiencing a rapid increase of total amount of transmitted data, and it is expected that it will increase threefold over the next five years. Fiber optic communication systems are well suited solution for transmission of rapidly increasing data amount. These optical systems are especially suitable in access networks to provide telecommunication services between service provider side and end users. Therefore, in order to ensure faster data transmission, it is necessary to look for new solutions how to improve the architecture and performance of optical access transmission systems. The research of high-speed WDM-PON and SS-WDM PON optical access systems, as well as development of spectrum sliced transceiver, which fully integrates into the infrastructure of next generation passive optical networks (NGPON), is made in this doctoral thesis. Research on sources of signal latency in optical transmission systems and solutions of reduction is made as well. As a result, thesis summarizes the completed research in which the current and future fiber optical access systems (NGPON) as well as their performance improvement techniques are evaluated.