Intensity holography

The liquid crystalline polymer (see Fig. 6.14) was filled and aligned in a cell consisting of rubbed polyimide surfaces. Making use of conventional intensity holography, they showed that rather high diffraction efficiency ( 50%) could be achieved with very low laser intensities (1 mW cm-2). 

FIGURE 6.15 Principle of (a) intensity holography and (h) polarization holography. 

For single-crystal substrates, there is additional information about the geometric structure of the surface contained in the intensity angular distribution (IAD) of the photoemitted electrons. This information is obtained in XPD measurements that often directly indicate bond directions at surfaces. A Fourier transform of the XPD data can also be used to determine element-specific surface structure in a method known as photoelectron holography. This approach can be used to directly determine surface structures without any starting model. 

In the case of azobenzene containing materials, it is preferable to use another type of holography called polarization holography [47]. The difference between intensity and polarization holography is illustrated in Fig. 6.15. In Fig. 6.15a, the two beams that are incident on the film (reference and object beams) have the same polarization... 

The concept of templated self-assembly of quantum dots has been transferred from molecular beam epitaxy to chemical vapour deposition. Here we demonstrate the fabrication of ordered arrays of Ge islands on a Si (100) surface using optical holography for the prepattern and subsequent growth by chemical vapor deposition. The samples were analyzed by atomic force microscopy and photoluminescence. Ordered arrays of Ge islands with a narrow size distribution and intense narrow photoluminescence lines of the islands have been observed. 

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