分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： In space-based gravitational wave detection, the estimation of far-field wavefront error of the distorted beam is the precondition for the noise reduction. Zernike polynomials is used to describe the wavefront error of the transmitted distorted beam. The propagation of a laser beam between two telescope apertures is calculated numerically. Far-field wavefront error is estimated with the absolute height of the peak-to-valley phase deviation between distorted Gaussian beam and a reference distortion-free Gaussian beam. The results show the pointing jitter is strongly related to the wavefront error. Furthermore, when jitter decreases 10 times from 100 to 10 nrad, wavefront error reduces for more than an order of magnitude. In the analysis of multi-parameter minimization, the minimum of wavefront error tends to Z[5,3] Zernike in some parameter ranges. Some Zernikes have a strong correlation with wavefront error of the received beam. When the aperture diameter increases at Z[5,3] Zernike, wavefront error is not monotonic and has oscillation. Nevertheless, wavefront error almost remains constant with the arm length increasing from 10$^{-1}$ Mkm to 10$^3$ Mkm. When the arm length decreases for three orders of magnitude from 10$^{-1}$ Mkm to 10$^{-4}$ Mkm, wavefront error has only an order of magnitude increasing. In the range of 10$^{-4}$ Mkm to 10$^3$ Mkm, the lowest limit of the wavefront error is from 0.5 fm to 0.015 fm, at Z[5,3] Zernike and 10 nrad jitter.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Superluminal tunneling of light through a barrier has attracted broad interest in the last several decades. Despite the observation of such phenomena in various systems, it has been under intensive debate whether the transmitted light truly carry the information of the original pulse. Here we report observation of anomalous time response for terahertz electromagnetic pulses passing through thin metal films, with the pulse shape of the transmitted beam faithfully resembling that of the incident beam. A causal theoretical analysis is developed to explain the experiments, though the theory of Special Relativity may confront a challenge in this exceptional circumstance. These findings may facilitate future applications in high-speed optical communication or signal transmission, and may reshape our fundamental understanding about the tunneling of light.
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