In this study, a wearable multichannel human magnetocardiogram (MCG) system based on a spin exchange relaxation-free regime (SERF) magnetometer array is developed. The MCG system consists of a magnetically shielded device, a wearable SERF magnetometer array, and a computer for data acquisition and processing. Multichannel MCG signals from a healthy human are successfully recorded simultaneously. Independent component analysis (ICA) and empirical mode decomposition (EMD) are used to denoise MCG data. MCG imaging is realized to visualize the magnetic and current distribution around the heart. The validity of the MCG signals detected by the system is verified by electrocardiogram (ECG) signals obtained at the same position, and similar features and intervals of cardiac signal waveform appear on both MCG and ECG. Experiments show that our wearable MCG system is reliable for detecting MCG signals and can provide cardiac electromagnetic activity imaging.

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Photonic techniques have potential to overcome the limitations of electronic digital-to-analog conversion. A serial optical DAC, using fiber dispersion with optical weighted wavelength multiplexing, is proposed and demonstrated. Serial Digital codes are overlapped regularly in time domain due to dispersion-based delays. Intensity information for the conversion is extracted by synchronous gating pulse train. The system is operated with a high precision time control. Performance of the ODAC is experimentally investigated by establishing a 4-b 12.5 Gb/s system. The linear transfer function is described and an ENOB of 3.55 is obtained. The proposed architecture could be easily modified for better performance.

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Based on the theory of circular polarization dichroism in electromagnetic fields, this paper studies the circular dichroism (CD) characteristics of metasurfaces. Using a stable silicon material, an innovative “double L-shaped” composite structure formed by two L crosses is proposed to improve CD. Under a wide spectrum with wavelengths of 1000–1500 nm, the left circularly polarized (LCP) and right circularly polarized (RCP) lights pass through the structure, and we study the influence of different structural parameters on the CD, in order to obtain the best structural parameters. These realize the cross polarization of left-right circularly polarized light. In addition, at the wavelength of 1302.63 nm, the LCP light illuminates the structure, which realizes the cross polarization of LCP light; that is, the structure realizes the function of a half-wave plate. The RCP light incident structure realizes the function of a filter. It has great application prospects in biological detection, half-wave plates, filters, and other fields.