A multiplexing technique named orthogonal waveform (graph) division multiplexing (OGDM) and its application on the upstream data transmission in passive optical access networks (PON) are proposed. N mutually orthogonal electrical waveforms are assigned to N optical network units (ONU). For intensity modulator, ONU′s code “1” means orthogonal electrical waveform and code “0” means no waveform. Those electrical orthogonal waveforms are modulated on lasers with the same wavelength and then are combined at optical distribution network (ODN) to be transmitted to optical line terminal (OLT) in a single fiber. At OLT, the mixed signals can be separated by using correlative demodulation method. Stimulation results show that, under external modulation, the transmission distance reaches 20 km with 320 Gb/s data transmission rates in ideal situation.