Self-bending Photonic Hook Beam into the Time Domain Based on Phase Change Materials

Tunable optical devices are of great interest as they offer adjustability to their functions. Temporal optics is an evolving new field, and utilizing it are useful as for revolutionize basic research of time-dependent phenomena as for leading toward full optical devices. With increasing focus on ecological compatibility, bio-friendly alternatives are of key subject. Water in its various forms can uniquely open up new physical phenomena and applications in photonics and modern electronics in unique ways. Water droplets freezing on cold surfaces are ubiquitous in nature. We propose and demonstrate the effectual generation of time domain self-bending photonic hook (time-PH) beams by using freezing water droplet. The PH light bend near the shadow surface of the droplet into large curvature and angles superior to a conventional Airy beam. The key properties of the time-PH (length, curvature, beam waist) can be modified flexibly by changing the positions and curvature of the water-ice interface inside the droplet. Due to the modifying internal structure of freezing water droplets in real time, we showcase the dynamical curvature and trajectory control of the time-PH beams. Compare with the traditional methods, our phase-change based materials (water and ice) of the mesoscale droplet has advantages of easy for fabrication, natural materials, compact structure and low cost. Such a PHs may have applications in many fields, including temporal optics and optical switching, microscopy, sensors, materials processing, nonlinear optics, biomedicine, and so on.