The concept of space-time duality, known since the 1960s, is attracting attention in recent years in the context of temporal imaging. In this talk I review these advances and discuss how a modulator can act as a time lens. I then focus on our recent work on the temporal analog of reflection and refraction of optical pulses inside a dispersive medium whose refractive index changes across a temporal boundary. As an optical pulse approaches this boundary, it splits into two parts that propagate at different speeds because of their widely different spectra. An analog of the total internal reflection also occurs when the refractive index change at the boundary is large enough. This phenomenon can be used to make a temporal waveguide that confines optical pulses within a temporal window. I also discuss how the nonlinear phenomenon of cross-phase modulation can be used for making such a temporal waveguide by employing a pump-probe configuration.

Govind Agrawal is the James C. Wyant Professor of Optics, Institute of Optics, University of Rochester, NY and the Editor-in-Chief of Advances in Optics and Photonics. He is a fellow of the IEEE and the Optical Society of America. He is a world-renowned author of several books in the fields of nonlinear fiber optics, semiconductor lasers, fiber-optic communication systems and light-wave technology. In 2012, Prof. Agrawal was awarded the Quantum Electronics Award by the IEEE Photonics Society. In 2015, he was awarded the Esther Hoffman Beller Medal by the Optical Society of America for "inspiring and educating a generation of scientists and engineers involved with fiber-optic communications and other photonics technologies through his seminal textbooks and high-impact scientific articles." In 2019 he was the recipient of two major awards: the Max Born Award of the Optical Society and the Quantum Electronics Prize of the European Physics Society.