While both technologies share a similar physical topology, WDM-PON employs passive WDM MUX/DEMUX devices for wavelength management, creating a wavelength-based point-to-point logical connection that ensures user resource isolation. While it follows the FTTx point-to-multipoint topology, there are marked differences between the two technologies: TDM-PON WDM-PON TDM-PON WDM-PON While both technologies. The passive optical network (PON) is an optical fiber based network architecture, which can provide much higher bandwidth in the access network compared to traditional copper-based networks. Incorporating wavelength-division multiplex-ing (WDM) in a PON allows one to support much higher bandwidth. A Wavelength Division Multiplexing Passive Optical Network (WDM-PON) is an advanced optical access network architecture that uses wavelength division multiplexing (WDM) to deliver high-bandwidth services to end-users. Each signal is assigned a unique wavelength of light, enabling independent data streams to coexist without. The authors have studied WDM-PONs with centralised lightwave source and direct detection, where a wavelength-reuse system is employed to transmit the uplink data by using a colourless transmitter at the optical network unit (ONU). This integration allows multiple wavelengths to transmit data over a single fiber, significantly enhancing efficiency.