Lee, Junhyung Moon, Sunghyun Park, Yongchan Park, Uijoon Kim, Hansol Kim, Changhyun Choi, Minho Lee, Jin-Il Hwang, Hyeon Seo, Min-Kyo Ahn, Dae-Hwan Jung, Hojoong Kwon, Hyounghan 2025-11-26T10:36:26Z 2025-11-26T10:36:26Z 2025-11-26 2025-12 2192-8606 https://pubs.kist.re.kr/handle/201004/153690 Nonlinear signal generation requires precise control of the input polarization to satisfy phase-matching conditions. Conventional polarization management using external fiber polarization controllers or bulk wave plates increases coupling complexity and can degrade polarization fidelity and conversion efficiency in nonlinear photonic systems. Here, we demonstrate on-chip polarization control in thin-film lithium niobate nonlinear photonic circuits. Integrated polarization modulators enable real-time tuning of arbitrary input polarization states and thus provide on-demand control of nonlinear conversion in a periodically poled lithium niobate waveguide. A closed-loop feedback system, which integrates auto-compensation and automatic fiber-chip alignment routines, automatically optimizes the second-harmonic generation intensity and maintains performance over extended periods despite polarization scrambling and environmental perturbations. This integrated approach reduces coupling complexity and offers a scalable route toward fully reconfigurable nonlinear photonic systems. English WALTER DE GRUYTER GMBH On-chip polarization management for stable nonlinear signal generation in thin-film lithium niobate Article 10.1515/nanoph-2025-0339 1 Nanophotonics, v.14, no.26, pp.4691 - 4701 Nanophotonics 14 26 4691 4701 Y scie scopus 001609431000001 2-s2.0-105021254929 Nanoscience & Nanotechnology Materials Science, Multidisciplinary Optics Physics, Applied Science & Technology - Other Topics Materials Science Optics Physics Article 2ND-HARMONIC GENERATION EFFICIENT OPTICS BIAS on-chip polarization management Stokes parameter lithium niobate periodically poled lithium niobate second harmonic generation feedback loop