Dynamic Polarization Control of Nonlinear Terahertz Photoresponse via Topological Phase Transitions
Libo Zhang, Xuyang Lv, Zhuo Dong, Debasis Dutta, Yang Liu, Raihan Ahammed, Atasi Chakraborty, Dong Wang, Zhen Hu, Mengjie Jiang, Kaixuan Zhang, Li Han, Kai Zhang, Amit Agarwal, Xiaoshuang Chen, Lin Wang
Abstract
Precise modulation of topologically protected states via external stimuli, such as electric, optical, and magnetic fields, is a cornerstone for advancing robust topological photonics and quantum technologies. However, the realization of dynamic and noninvasive control remains constrained by the high-energy thresholds of conventional stimuli, which can disrupt delicate topological states. Here, we employ low-energy terahertz excitation to directly probe the photoresponse across a temperature-induced topological phase transition in ultrathin ZrTe 5 , a material at the intersection of topological physics and low-dimensional systems, leveraging its unique ability to interact with low-energy quasiparticle states without compromising coherence in the system. We observe a giant and robust nonlinear terahertz photoresponse characterized by in situ tunable geometric properties of Bloch quasiparticles. The response exhibits colossal behavior and a sign reversal across a temperature-driven topological phase transition, linked to a nonvanishing Berry curvature dipole that serves as a direct marker of symmetry-breaking evolution between weak ( m < 0) and strong ( m > 0) topological insulator phases. The observed device exhibits a response time of ~1 μs with a noise equivalent power of 5.6 pW/Hz 0.5 across the 0.5-THz range, demonstrating the potential of topological phase transitions for terahertz detection. These findings underscore the potential of low-energy terahertz excitation for dynamically polarizing and controlling topological states in ultrathin materials, offering a versatile framework for exploring symmetry-breaking phenomena and advancing next-generation optoelectronic devices.