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

Abstract

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.

Long-Duration Optical Pulse Shaping and Complex Coding on SOI

“…Direct time-domain characterization of the output, synthesized waveforms has been carried out using Fourier-transform spectral interferometry (FTSI) where the input pulse itself is used as the reference [10], [17]. As shown in Fig.…”

“…To overcome the aforementioned limitations, we have recently proposed and experimentally demonstrated a compact on-chip OPS design based on weakly-coupled cascaded co-directional couplers, and have shown the capability of this approach to achieve sub-picosecond temporal resolutions [9], [10]. Based on this design, the so-called discrete apodization profile of cascaded co-directional couplers can be directly mapped into the output temporal response of the device.…”

“…Previous experimental demonstrations of on-chip D-STM have achieved sub-picosecond intensityonly and phase-only OPS. In particular, flat-top pulses with duration ranging from 440 fs up to ∼3 ps, and an 8-bit 0.6-Tbit/s phase-coded pulse sequence with four different phase levels have been successfully generated in silicon [10].…”

On-chip silicon photonic signaling and processing: a review

“…linear and nonlinear photonic signal processing. Linear photonic signal processing includes switching [54,55], filtering [56][57][58][59][60], optical pulse shaping [61,62], differentiation [63][64][65][66], wavelength/mode/polarization (de)multiplexing [67][68][69][70][71], and so on. Nonlinear photonic signal processing exploits various nonlinear phenomena.…”

“…However, devices based on the aforementioned material platforms have relatively large footprint, and are lack of abilities for massive integration. The development of silicon photonics offers the possibility to perform photonic signal processing on an ultracompact silicon chip [54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][102][103][104][105][106][107][108][109][110][111][112][113][114]. Silicon-on-insulator (SOI) platform is quite suitable for linear photonic signal processing for its low loss and ultracompact footprint.…”