Parametric all-optical modulation on a chip

We demonstrate parametric all-optical modulation in a periodically poled lithium niobate microring resonator on a chip. It uses quantum Zeno blockade between two distinct waves, a signal and a pump, through their sum-frequency generation at a large per-photon efficiency of 8.2 MHz. With nanosecond pump pulses with 6-mW peak power, 85.7% modulation extinction is observed, achieving an efficiency increase of more than 30 times compared with previous implementations. With only 2-mW pump peak power, 43.0% modulation extinction is observed for a twice-as-strong signal of 4 mW. This demonstrates that optical transistors with cascadability and fan-out are possible with just parametric nonlinear optics. These results, together with inherent advantages in such photonic integrated circuits, open the door to scalable technology for all-optical and quantum information processing.