Measurement and Analysis of Defect Modes in 2D and 3D GaAs Photonic Crystals
Date Issued
2007
Date
2007
Author(s)
Shih, Pi-Kuei
DOI
zh-TW
Abstract
Photonic crystals are materials with periodical dielectric constants. The band gap occurs according to the destructive interference, where certain wavelengths are not allowed to pass through. The light at those frequencies can not find a real propagation constant and thus will be scattered. Besides perfect photonic crystals, we are more interested in those photonic crystals with defects because those modes resulted from the defects are spatially confined in comparison with those non-defect modes. In other words, we can control the behavior of the defect modes by adjusting the fine structures in the photonic crystal. This is a very interesting phenomenon. An example of this is the photonic crystal waveguide, where lights will propagate along the direction we design.
By developing automatic measurement techniques, we can acquire correct and stable information efficiently. For two-dimensional slab structures, we focus on the resonant cavities formed by the photonic crystals and expect to observe the resonant modes and the field distribution. With the assistance of the motorized stage, we could stably scan the spatial light intensity distribution and then observe the spectrum and the field intensity distribution of the defect modes. With the spectrum and the field distribution of the defect modes, we could understand more about the effects of the resonator. In the structure we designed in this work, we successfully find two resonant modes around 952nm and 960nm on the spectrum by observing the transmitted and the scattered spectrum. On the other hand, owing to the difficulty in constructing the point-defect by the auto-cloning method in three-dimensional checkerboard structures, we designed line-defects instead and then observed the effect from them. We observed the spectra and the spatial distribution of the defect modes. But we can’t find the obvious difference in spatial field distribution between two defect structures which have different sizes. It’s probably limited by the detection resolution and stability.
Subjects
光子晶體
二維
三維
缺陷結構
Photonic Crystal
2D
3D
defect structure
Type
thesis
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