Interference, four-beam

Fig. 2. Calculated intensity distribution for (a) two-beam interference (d), (b) three-beam interference assuming symmetrical configuration (e), and (c) four-beam interference under the conditions shown in (f). Reproduced with permission — Copyright Carl Hanser Verlag GmbH Co. KG.

FCC Structure Realized with Four-Beam Interference. 237... 

The two-step interference method, although technically a little complicated, has the freedom to design arbitrary lattice constants of different lattices. This is its significant merit compared with the single-step four beam interference by Campbell et al., which will be introduced in 4.6.3. 

Finally, it should be mentioned that periodic deformations can be produced through interferences of four beams (Trunov et al., 2009] and pulsed light (Vlcek et al., 2009]. Also, Kokenysi s group has demonstrated formation of relief gratings in multilayered chalcogenide films such as Se/As2S3 (Takats et al., 2009], in which photoinduced material diffusion is probably responsible. 

Laser polarization is essential for designing interference patterns [169]. The lattice in Fig. 41a is created by interfering four beams with identical polarization so that all of them interact with each other. However, if the polarizations of the beams are (i) (ii) and (iii)J.(iv), and (i) (iii) or (i) (iv), Hght of perpendicular polarizations don t interact with each other, so that the interference pattern is a simple addition of two sets of two-beam interference planes (Fig. 41b). In both cases, the Scheme 1 beam geometry in Fig. 40 was utilized. 

Fig. 41 Calculated interference patterns with FCC symmetry produced by four beams with different polarizations. The 500 nm scale bars correspond to a laser wavelength 355 nm the lattice constant is 397 nm. a all 4 beams have identical linear polarization, and b beam arrangement corresponds to those in Scheme 1, but with polarizations (i)-L(ii) and (iii) L(iv), and (i)//(iii) or (i)//(iv)...

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