Large-Scale Photonic Chip Based Pulse Interleaver for Low-Noise Microwave Generation

We demonstrate a 64-times multiplication of a mode-locked laser’s 217 MHz pulse repetition rate to 14 GHz using an integrated Si \(_3\) N \(_4\) interleaver. Six cascaded stages of Mach-Zehnder interferometers with up to 33 cm long optical delay lines are fully integrated into a very compact footprint of 8.5 mm \(\times \) 1.7 mm. By overcoming photodetector saturation during the high power peak, the generated microwave power was improved by 36 dB, which reduces the phase noise floor by more than 10-fold to −160 dBc/Hz on the 14 GHz carrier.