TOAD-based optical data format converter

An optical data format converter and method using a Terahertz Optical Asymmetric Demultiplexer (TOAD) to increase or decrease the duty cycle of an optical signal. To increase the duty cycle, such as converting RZ pulses to NRZ format, the optical data is injected at the clock input port of the TOAD and a continuous wave (CW) laser feeds the data input port. A stretched copy of the input signal will appear at the output port of the TOAD, with the output pulse width determined by the TOAD sampling window. To decrease the duty cycle, the optical data is injected at the data input port of the TOAD and a pulsed control signal is injected at the clock input port. The switching window is selected to be smaller than that period of the NRZ signal causing only the portion of the NRZ signal that overlaps the window to appear at the output of the TOAD.