利用超低噪声 qCMOS^® 技术推进超快磁光成像

2026 年 3 月 12 日发布

超快泵浦探测实验能够通过磁光效应准确研究磁化动力学。这使得研究人员能够监测磁性材料在超短时间间隔内的行为变化，从而深入了解基础物理学并促进新技术的发展。这里我们重点介绍使用在检测单个 50 fs 脉冲产生的微弱信号方面表现优异的 qCMOS 相机进行单次拍摄全光电开关实验。低噪声和高量子效率特性使其成为捕捉高空间分辨率的超快磁变的理想选择。

单次拍摄全光电开关实验
适用于单次拍摄全光泵浦探测实验的 ORCA^®-Quest 的优势
未来研究展望
Researcher profiles
参考资料

单次拍摄全光电开关实验

过去二十年间，激光脉冲激发已成为极适合进行磁化动力学研究的工具之一。该研究领域揭示了磁化光控制的全新而复杂的机理。它因其强大的科学吸引力与前景无限的商业用途（例如磁阻随机存取存储器 (MRAM)、自旋逻辑设备和赛道存储器）引发广泛关注。全光泵浦探测实验通过磁光效应测量磁化强度的变化，具体来说是光偏振旋转与磁化强度成比例的角度。使用超短脉冲光源可实现亚皮秒时间分辨率，进而详细研究脉冲激发后磁化随时间的变化。但在不可逆全光电开关过程中检测单个 50 fs 脉冲的微弱磁光信号仍是一大挑战 [1]。

适用于单次拍摄全光泵浦探测实验的 ORCA^®-Quest 的优势

在磁化动力学研究中，科学相机的主要功能是以（亚）微米空间分辨率检测磁光信号。这种相机需满足的关键要求包括在目标波长下具备低噪声和高量子效率特性，因为信号是由单个约 50 fs 激光脉冲发送的。此外，实验中的偏振旋转可低至几毫度。由于单个激光脉冲所含光子数量有限，故像 ORCA-Quest 这类具备低读出噪声和短曝光时间特性的专业相机堪称理想之选。该相机还需具备其他基本特点，包括与设置中的激光器和其他电子设备可靠同步、高动态范围、像素位深度以及与可适配的软件无缝集成。

如同众多超快磁光成像研究人员一样，我们使用了 CCD 相机。但凭借其无与伦比的低读出噪声特性，qCMOS 传感器有望带来革命性突破。此外，我们在其他激光诱导动力学实验中测量了光学二次谐波图像，其曝光时间长达几分钟。同样，凭借其高量子效率、大量像素和板载像素合并选项，ORCA-Quest 能够提供高质量的图像。

Example of optically switched magnetic areas 1

Example of optically switched magnetic areas 2

光电开关磁区示例：亮色和暗色分别代表磁化平面外分量的相反取向。在两幅图像中，泵浦区中心完全消磁并形成多磁畴模式。外边缘被切换，还可通过第二个激光脉冲实现来回切换。这在重叠的激光脉冲区域中可见，进而产生明暗变化区。

扫描模式：超静音扫描模式；读出模式：区域；4×4 像素合并，触发器：全局复位。曝光时间：（左）33.94 μs = 单个 100 fs 探测脉冲，（右）100 ms = 100 个探测脉冲。

未来研究展望

未来，该技术将拓展到零净磁化强度反铁磁材料领域。此类材料中磁畴的可视化极具挑战性，需借助先进的线性与非线性光学技术方可实现[2, 3]。

综上所述，ORCA-Quest 相机通过可靠地检测超快激光脉冲产生的微弱信号来促进单次拍摄磁光成像。其性能可同时满足单次切换研究及长曝光时间成像的需求。未来研究中，此方法将拓展至反铁磁材料领域，届时需借助先进的光学技术实现磁畴可视化。这将有助于我们进一步加深对磁化控制的理解，并推动其在 MRAM、自旋电子器件及其他领域中潜在用途的发展。

Researcher profiles

Dr. Nikolai Khokhlov
Postdoc at Ultrafast Spectroscopy of Correlated Materials group, Radboud University, The Netherlands

Dr Nikolai Khokhlov is a postdoc at Ultrafast Spectroscopy of Correlated Materials group, Radboud University, The Netherlands. He received his Ph.D. in Physics from M.V. Lomonosov Moscow State University, and completed postdoctoral training at Russian Quantum Center (Moscow, Russia). He then joined the Ferroics Physics Lab of Ioffe Institute (St. Petersburg, Russia) as assistant professor prior to his current position at Radboud University. Dr Khokhlov’s research centers around laser-induced ultrafast dynamics and all-optical switching of ferri- and antiferro-magnets implementing ultrafast magneto-optical microscopy technique.

Paul van Kuppevelt, MSc
Ph.D. candidate at the Ultrafast Spectroscopy of Correlated Materials group, Radboud University, The Netherlands

Currently, Paul van Kuppevelt performs his Ph.D. in physics at the Radboud University in Nijmegen. Before starting his research, he studyied physics at the Eindhoven University of Technology where he obtained his Bachelor’s and Master’s degree. During both his Bachelor’s and Master’s thesis, he focussed on the interaction of light with matter. At first by comparing models and experiments of the plasmon resonance in gold nanoparticles and later by performing logic operations with circular polarized light pulses in magnetic multilayer nanofilms. Now he continues in this field for his Ph.D. He is searching for ways in which to change and manipulate the magnetic state of ferri- and antiferromagnets to control the ultrafast dynamics inside these materials, which can be leveraged for applications like magnetic computing and data storage.

Wiebe Leenders, BSc
Master student at Ultrafast Spectroscopy of Correlated Materials group, Radboud University, The Netherlands

A Master’s student in physics, Wiebe Leenders is currently conducting research internship with the Ultrafast Spectroscopy of Correlated Materials group at Radboud University. Building on his previous research experience in material science and photovoltaics, he now focuses on optically excited ultrafast spin dynamics. Upon completion of internship, he will continue exploring magnetic materials and their potential for neuromorphic computation paradigms.

*本页显示的内容为采访时的可用信息。

参考资料

[1] Hashimoto, Yusuke, et al. "Ultrafast time-resolved magneto-optical imaging of all-optical switching in GdFeCo with femtosecond time-resolution and a μm spatial-resolution." Review of Scientific Instruments 85, 6 (2014).

[2] Hayashida, T., et al. "Observation of antiferromagnetic domains in Cr₂O₃ using nonreciprocal optical effects." Physical Review Research 4(4), 043063 (2022).

[3] Fiebig, Manfred, et al. "Second harmonic generation and magnetic-dipole-electric-dipole interference in antiferromagnetic Cr₂O₃." Physical Review Letters 73(15), 2127 (1994)

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