Wang Zhi-Yan, Wu Xiao, Xiong Xiao, Yang Chen, Hao Zhenzhong, Yang Qi-Fan, Hu Yaowen, Bo Fang, Cao Qi-Tao, Xiao Yun-Feng
State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, New Cornerstone Science Laboratory, School of Physics, Peking University, Beijing 100871, China.
MOE Key Laboratory of Weak-Light Nonlinear Photonics, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin 300457, China.
Sci Adv. 2025 May 2;11(18):eadu7605. doi: 10.1126/sciadv.adu7605.
Integrated nonlinear photonics has emerged as a transformative platform, enabling nanoscale nonlinear optical processes with substantial implications. Achieving efficient nonlinear frequency conversion in microresonators is paramount to fully unlocking this potential, yet the absolute conversion efficiency (ACE) remains fundamentally constrained by dissipative losses and intrinsic nonlinear effects. In this work, we establish a unified framework for second harmonic generation in microresonators, identifying a decisive factor that predicts the ACE limit under the nonlinear critical coupling (NCC) condition. Using this framework, we fabricate periodically poled lithium niobate microresonators and address the dispersive-dissipative suppression to approach the NCC condition. We achieve a record-high ACE of 61.3% with milliwatt-level pump powers toward the ultimate efficiency, with the potential for higher efficiency as the factor increases. These results provide a versatile paradigm for high-efficiency nonlinear optical devices, offering opportunities for advancements across classical and quantum photonic applications.
集成非线性光子学已成为一个变革性平台，能够实现具有重大意义的纳米级非线性光学过程。在微谐振器中实现高效的非线性频率转换对于充分释放这一潜力至关重要，但绝对转换效率（ACE）仍从根本上受到耗散损耗和固有非线性效应的限制。在这项工作中，我们建立了一个用于微谐振器中二次谐波产生的统一框架，确定了一个决定性因素，该因素可预测非线性临界耦合（NCC）条件下的ACE极限。利用这个框架，我们制造了周期性极化铌酸锂微谐振器，并解决了色散 - 耗散抑制问题以接近NCC条件。我们在毫瓦级泵浦功率下实现了创纪录的61.3%的ACE，朝着最终效率迈进，随着该因素增加，还有提高效率的潜力。这些结果为高效非线性光学器件提供了一个通用范例，为经典和量子光子应用的发展提供了机会。
