Kristir Shalm: Photonic Time-Crystals

Date: Wednesday June 3rd, 2026

Location: Elings Hall, 1601

Time: 11:00am

Photonic Time-Crystals

Abstract: Photonic Time Crystals (PTCs) are dielectric media whose refractive index is strongly modulated periodically in time at time scales of a single optical cycle. These systems conserve momentum but not energy, and are characterized by momentum bands and bandgaps where the amplitudes of their eigenmodes can increase or decrease exponentially. The fundamentals of PTCs will be introduced along with the classical and quantum features of light-matter interactions in PTCs. Among these, the most notable is the emission of light in PTCs, which opens new avenues for making widely tunable lasers that do not rely on any atomic resonance and draw their energy from the temporal modulation of the medium. Finally, I will discuss recent experimental progress on timerefraction in the regime of a sub-optical cycle and realizing time-reflection at optical frequencies.

Bio: Ohad Segal is currently pursuing a PhD under the supervision of Distinguished Professor Mordechai Segev, a world-renowned expert in nonlinear optics and photonics. Ohad’s research focuses on photonic time crystals, a cutting-edge field with applications such as tunable coherent light sources and quantum light generation. His research combines his passion for waves (which originated from surfing) and scientific curiosity to explore novel optical-wave phenomena in experiments and theory. He has published several papers and received awards and scholarships for academic achievements and is committed to advancing knowledge and skills in this field.