The characteristics of all optical networks such as high speed, data carrying capacity and transparency make them suitable for emerged networks domain. This paper presents an overview of research challenges in the field of all optical communication networks. Various subdomains of an all optical system, for example device-level designs, communication technique-level designs and network-level designs have been extensively investigated and presented in this paper. Further, the related research issues under each category of these domains have been discussed. These issues constitute the basic criterion for further development in all optical domain.