Detection of magneto-optical Kerr signals via weak measurement with frequency pointer

Precise measurement of chiral spectrum in the ultraviolet band using weak measurement and a deep neural network model

Circular dichroism (CD) spectrum and optical rotation (OR) spectrum, crucial for understanding molecular properties and configurations, present challenges due to limited testing methods and equipment accuracy in the ultraviolet (UV) region. This study proposes a weak measurement system for chiral signals in varying concentrations in the ultraviolet range, optimized using a deep neural network (DNN) model. Introducing different post-selections to detect the circular dichroism spectrum and optical rotation spectrum separately, with contrast as a probe, it achieves a detection resolution of up to 10-6 rad. Moreover, the fitted value of the training data can reach 0.9989, enhancing the prediction accuracy of chiral molecule concentrations. This method exhibits considerable promise for applications in chiral measurement and sensor technologies.

Observation of the mixed magneto-optical Kerr effects using weak measurement

In this paper, we use weak measurement to study the mixed magneto-optical Kerr effects (MOKEs) in a magnetic single layer of Co and in organic/Co bilayer films. The relationship between the amplified shift and the MOKE parameters is theoretically established and then experimentally observed as a function of both the magnetization intensity and the magnetization direction in magnetic thin films with an arbitrary magnetization. Furthermore, we experimentally observe a magnetic coupling at the organic/ferromagnetic interface. Due to this being a robust coupling, there is a significant dependence of the amplified shift with the thickness of the organic layer. This work has value for its application in the magnetic measurement technique for the more general case based on weak measurement.

Estimation of Kerr angle based on weak measurement with two pointers

In this paper, we propose a weak measurement method using two pointers to estimate the magneto-optical Kerr angle, which is robust to ellipticity. The double pointers are the amplified displacement shift and intensity of the post-selected light beam, which are the conventional information carried by the light beam and can be directly output by a detector (such as a charge-coupled device). We demonstrate that the product of the double pointers is only related to the phase variation between two basic vectors and independent of the amplitude errors. In the measurement process, when there is an amplitude change or additional amplitude noise between two eigenstates, the product of two pointers is very useful in extracting phase information and shielding amplitude noise. In addition, the product of two pointers has a good linear relationship with the phase variation and a larger dynamic measurement range. This method is applied to measure the magneto-optical Kerr angle of NiFe film. The Kerr angle can be directly obtained using the product of the light intensity and the amplified displacement shift. This scheme is of great significance for the measurement of the Kerr angle of magnetic films.

Transformation from asymmetric spin splitting to symmetric spin splitting with phase compensation in photonic spin Hall effect

Generally, when an arbitrary polarized light beam is reflected or refracted from an isotropic interface, the spin splitting in photonic spin Hall effect (SHE) shows asymmetry properties. In this paper, we theoretically propose a phase compensation scheme to achieve the transformation from asymmetric spin splitting to symmetric spin splitting in photonic SHE. We experimentally acquire the spin splitting after phase compensation in the case of a 45 degrees linear polarized Gaussian light beam totally internally reflected from a prism-air interface. Particularly, whether or not phase compensation, the transverse shift of total barycenter of reflected field [i.e., the Imbert-Fedorov (IF) shift] does not change. These findings can solve this problem that asymmetric spin splitting cannot be observed by weak measurements.