The terahertz (THz) spectral range offers a platform for experimentally collecting electromagnetic pulses to analyze the intrinsic resonances of matter and has become an important field for applying intrinsic responses to future information devices. However, a lack of numerical methods for signal denoising exists in the knowledge of the THz spectral range. In this paper, numerical methods that employ the Bézier curve and its generalization ( B -spline) to denoise thermally tunable and thickness-dependent terahertz signals are proposed. Different thicknesses of ErFeO 3 are chosen and prepared. Both Bézier curves and B -splines have the ability to denoise the signals and the effect of the Bézier curves on the noise is close to but slightly less than that of the B -splines. Additionally, the B -splines show a better noise reduction effect and have better signal strength stability and robustness than do the Bézier curves. Thus, B -splines are applied to process the raw data, and quantitative insight into the trend of the resonant frequencies, peak heights, and transmittances of antiferromagnetic resonance and ferromagnetic resonance with temperature is obtained.
Rare-earth orthoferrites with weak ferromagnetism have become one of the most fascinating topics in antiferromagnet research because of their potential application in future information technologies. However, an appropriate and direct way to reduce the noise in the intrinsic but weak resonances of rare-earth orthoferrites is currently lacking, creating difficulties in analysis. Here, we report a numerical smoothing method to directly denoise the detected terahertz (THz) responses of orthoferrites using a B -spline algorithm. For comparison, the Savitzky–Golay smoothing method, which is a typical and widely used numerical smoothing method, was also used to process the data. The thickness-dependent signals of DyFeO 3 were processed by the above methods. LaFeO 3 , HoFeO 3 , and DyFeO 3 were chosen and prepared, and their thermally tunable signals were processed. The B -spline signal smoothing algorithm was shown to have stability and robustness to noise and was more effective than the Savitzky–Golay smoothing method at reducing noise. This work on smoothing thickness- and temperature-dependent THz signals may help provide a promising approach to reduce noise in the intrinsic but weak resonances of rare-earth orthoferrites.
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