Optical code division multiple access (OCDMA) techniques have attracted much attention by allowing each communicating subscriber’s simultaneous access of the entire medium with maximum security and spectral efficiency. This paper aims to design and analyze 2 dimensional OCDMA based coding scheme and corresponding network architecture to support high capacity Gigabit Passive Optical Network (GPON). The coding scheme is proposed by deploying diagonal eigenvalue unity (DEU) scheme at the frequency domain (X-axis) in combination with double weight zero cross-correlation (DW-ZCC) code at the time domain (Y-axis). The proposed 2D-DZ coding scheme provides high orthogonality in adjacent codes and resolves the problem of larger code lengths. The new coding scheme and corresponding network architecture is analyzed in terms of Gaussian Approximation analysis and simulation through OptiSystem. It is observed that the proposed 2D-DZ based OCDMA system supports data rate of up to 2 Gbps for relatively large number of subscribers and extended reach in comparison with the existing counterparts.