Xinyuan Hu, Shulin Wang, Chengzhi Qin, Chenyu Liu, Lange Zhao, Yinglan Li, Han Ye, Weiwei Liu, Stefano Longhi, Peixiang Lu, Bing Wang
Advanced Photonics, Vol. 6, Issue 04, 046001, (July 2024) https://doi.org/10.1117/1.AP.6.4.046001
TOPICS: Electric fields, Phase modulation, Optical modulators, Solids, Pulse signals, Polarization, Optical coherence, Bessel functions, Signal processing, Physical coherence
Super-Bloch oscillations (SBOs) are amplified versions of direct current (dc)-driving Bloch oscillations realized under the detuned dc- and alternating current (ac)-driving electric fields. A unique feature of SBOs is the coherent oscillation inhibition via the ac-driving renormalization effect, which is dubbed as the collapse of SBOs. However, previous experimental studies on SBOs have only been limited to the weak ac-driving regime, and the collapse of SBOs has not been observed. Here, by harnessing a synthetic temporal lattice in fiber-loop systems, we push the ac-field into a strong-driving regime and observe the collapse of SBOs, which manifests as the oscillation-trajectory localization at specific ac-driving amplitudes and oscillation-direction flip by crossing collapse points. By adopting arbitrary-wave ac-driving fields, we also realize generalized SBOs with engineered collapse conditions. Finally, we exploit the oscillation-direction flip features to design tunable temporal beam routers and splitters. We initiate and demonstrate the collapse of SBOs, which may feature applications in coherent wave localization control for optical communications and signal processing.