Metamaterials, artificial materials with sub-wavelength structures capable of exhibiting novel electromagnetic behaviors that could be found in natural materials, have been actively perused as a hot research topic in recent years. The small feature sizes have led to challenges in characterizing the properties of the metamaterials. In this thesis, I aim to develop a technic to measure reflection phase of small samples as the existing methods, such as Ellipsometry, work only for bulk samples. We use a Fabry–Pérot etalon with variable gap-spacing together with a microscope’s objective to obtain reflection interference from areas down to 100 X 100 μm² in the visible range. We find the reflection interference peaks and troughs shifted by a slowly-varying envelope due to numerical effect of t...[ Read more ]

Metamaterials, artificial materials with sub-wavelength structures capable of exhibiting novel electromagnetic behaviors that could be found in natural materials, have been actively perused as a hot research topic in recent years. The small feature sizes have led to challenges in characterizing the properties of the metamaterials. In this thesis, I aim to develop a technic to measure reflection phase of small samples as the existing methods, such as Ellipsometry, work only for bulk samples. We use a Fabry–Pérot etalon with variable gap-spacing together with a microscope’s objective to obtain reflection interference from areas down to 100 X 100 μm² in the visible range. We find the reflection interference peaks and troughs shifted by a slowly-varying envelope due to numerical effect of the objective such that the as-measured reflection phase is coupled with the as-measured airgap of the FP etalon. A detailed analysis based on a 2-beams model for the interferogram, with the effect of converging incident beam taken in account, is presented in this work and corrections are applied to the interference peak/trough positions to obtain good agreements with standard values. Furthermore, our method is applied to the measurement of reflection phase of micron-sized Au-sawtooth gratings, demonstrating the potential of our technique in the characterization of small samples.