电子学领域的群速超光速实验

研究了电信号在阻抗周期失配的光子晶体结构中的群速超光速传播问题,构建了一种具有周期失配性的结构,此种阻抗失配引起非正常色散以及在8 MHz附近出现禁带.正弦调幅信号和窄脉冲信号分别被送入两种超光速实验装置. 实验结果表明,正弦调幅信号在禁带出现群速超光速,群速最大可达到3.52倍光速,而窄脉冲信号始终以正常速度传播.     

Negative and Superluminal Group Velocity Propagation with Narrow Pulse in a Coaxial Photonic Crystal

We investigate the propagation of electric signal along a spatially periodic impedance mismatched transmission line group. Anomalous dispersion is caused by the periodically mismatched impedance structure and a forbidden band appears near 8 MHz in transmission. The group velocity of the amplitude-modulated signal is augmented up to infinity, even -3.89c （c the speed of light in vacuum） in the forbidden region with the amplitude of the modulated signal increasing. When the carrier sinusoid signal is modulated in amplitude by the modulating sinusoid signal, of which the peak is superimposed with a narrow pulse at fivefold frequency, the superluminal group velocity also occurs. The experiment failed to show whether the propagation velocity of narrow pulse exceeds c or not.     

A Super High Resolution Distance Measurement Method Based on Phase Comparison

Phase comparison method can enhance the measurement resolution to 10^-13/T in time domain. This method can also be used in distance measurement in the navigation and positioning. We propose a super high-resolution distance measurement based on linear phase comparison method. A high resolution scheme is put forward on the basis of the research of major factors concerning the phase comparison in the distance measurement. Conversion of a high-linearity phase difference to voltage and high-resolution voltage meter make it possible to obtain a very high phase measurement resolution. When the purpose is to measure distance, the phase noise of frequency source used in the measurement can be reduced partly. Thus this method is favourable for high resolution distance measurement. The precision of the distance measurement can reach 0.1c ps with c being the velocity of light in vacuum.