This paper describes the implementation of an energy efficient Optical Network Unit (ECONU) on an Altera Stratix 4GT Field Programmable Gate Array (FPGA). An overview of the ECONU architecture along with its frame format design is also provided. The Finite State Machine (FSM) implementation for switching the ONU "on" and "off" is based on the sleep request encoded in the frames. The performance of the ECONU prototype is evaluated through hardware testbed and the obtained results are also discussed.