channel, a resonator first demultiplexes a spectral slice of an input optical signal and routes it to a therm phase shifter before being multiplexed back onto a common output waveguide via a second identical res A six-channel system (twelve resonators and six phase shifters) is built on the SOI platform fabricated by Photonics. Resonators are designed using multimode waveguides for the benefit of a reduced sidewall ro and propagation loss. A single shaper channel exhibits a ∼ 900 MHz linewidth, ∼ 115 GHz FSR, and ∼ 6 d sertion loss. Doped silicon slabs placed adjacent to the waveguides are used for thermo-optic tuning of re and phase shifters. Loopback waveguides are formed from both the input and output of the shaper. Our f setup is also shown in Fig. 1(a).Using the loopback waveguide bidirectionally and employing spectral filters, we simultaneously perform multi-heterodyne spectroscopy (MHS) and dual-comb spectroscopy (DCS) me ments on two adjacent free spectral ranges (FSRs) of the shaper (Fig. 1(c)) to rapidly (∼ µs) query the re frequencies of resonators on both sides of the shaper and the phases applied to each line, respectively. B the power from one of the EO combs used for DCS and routing it to the waveform monitor section in Fig. can view the temporal profile of six comb lines after propagation through the shaper in real time. A Pytho routine (block diagram in Fig. 1(b)) is written to actively tune channels onto a particular frequency grid a distinct phases with feedback from MHS and DCS signals.

As a demonstration of our method, we synthesize three waveforms from six optical lines of the 3 GHz E The ideal waveforms, the measured and ideally measured (given our measurement system response) wa and the measured phase on each shaper channel are shown in Fig. 2(a-i). The first demonstration is to co the six lines from the EO comb to form transform-limited pulses. The MHS scheme is run to align channel a 3 GHz grid without tuning the phases. However, in our scheme phase shifters are driven at the start to slightly higher than π phase. The temporal waveform is shown in Fig. 2(b) (black dotted trace) for these s phases. With phases tuned, the pulses are compressed (blue trace in Fig. 2(b)). The spectral transmission system for this state is shown in Fig. 1(c),and the untuned and tuned phases are shown in Fig. 2(c).Next,we target two additional waveforms: a doubled repetition-rate waveform following the temporal Talbot effec third waveform we denote the forked state.

The various results for these states are shown in Fig. 2(d-i).These waveforms are highly sensitive to phase deviations and therefore phase tuners needed to be iteratively o in fine steps to achieve the agreement shown in the figures. This requirement could be eliminated with a measurement of the reference EO comb phase.

In conclusion, we experimentally demonstrated a scheme for programming microresonator-based spec shapers. A set of three waveforms are synthesized using a six-channel sub-GHz resolution SOI shaper. Th shows promise towards realizing fully integrated fine-resolution pulse shaping systems for the next gene pulse shaping applications.