Precise On-Chip Spectral and Temporal Control of Single-Photon-Level Optical Pulses

The constantly growing need for fast and secure optical communication systems resulted in the rapid development of classical and quantum photonic technologies. Continuous research on improving the capacities of communication channels and the efficiency of optical information processing systems were naturally followed by miniaturization. Photonic integration combined with spectral-temporal multiplexing has led to improvements in communications. In this paper, we present accurate control of temporal and spectral profiles of optical pulses generated at the telecom wavelengths using an indium phosphide-based photonic integrated circuit. The device enables simultaneous temporally and spectrally resolved measurements using single photon counting. We discuss its applications in multidimensional time-frequency quantum key distribution, where security relies on time-frequency uncertainty, and other applications.