Experimental demonstration of sub-picosecond optical pulse shaping in silicon based on discrete space-to-time mapping

We experimentally demonstrate on-chip optical pulse shaping based on discrete space-to-time mapping in cascaded co-directional couplers. The demonstrated shapers validate a recent design methodology that exploits the direct relationship between the discrete complex spatial apodization profile of a structure of cascaded couplers and the time-domain impulse response of the device. In this design, the amplitude and phase of the apodization profile can be controlled through the coupling strength of each coupler and the relative time delay between the waveguides connecting consecutive couplers, respectively. This design methodology has been successfully used to demonstrate direct synthesis of high-quality flat-top and phase-coded pulse trains with resolutions down to the sub-picosecond range using passive devices in a silicon-on-insulator platform.