This essay explains the rationale underpinning the phenomenon that it is difficult to simultaneously perform well in
the dimension of complexity, accuracy and fluency in IELTS Speaking by the use of Trade-off Hypothesis and Skill Acquisition
Theory, which gives implications for IELTS Speaking learning.
The arbitrary Nth-order intensity correlation measurement with thermal light is both theoretically and experimentally investigated. In a double-slit interference scheme with thermal light, we compare the results for higher- and lower-order intensity correlation and demonstrate that the visibility of the interference pattern can be dramatically enhanced while the resolution can also be improved when the order N becomes larger. The experimental results are in agreement with our theoretical analysis.
Phase reversal occurs in the propagation of an electromagnetic wave in a negatively refracting medium or a phase-conjugate interface. Here we report the experimental observation of phase-reversal diffraction without the above devices. Our experimental results and theoretical analysis demonstrate that phase-reversal diffraction can be formed through the first-order field correlation of chaotic light. The experimental realization is similar to the phase-reversal behavior in negatively refracting media.
The time-reversal process provides the possibility to counteract the time evolution of a physical system. Recent research has shown that such a process can occur in the first-order field correlation of chaotic light and result in the spatial interference and phase-reversal diffraction in an unbalanced interferometer. Here we report experimental investigations on the invisibility cloak and illusion phenomena in chaotic light. In an unbalanced interferometer illuminated by thermal light, we have observed the cloak effect and the optical transformation of one object into another object. The experimental results can be understood by the phase-reversal diffraction, and they demonstrate the theoretical proposal of similar effects in complementary media.
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