Multilayered waveguides

Figure 2. Waveguide structure as a concatenation of several multilayer waveguide sections.

J Chilwell and I Hodgkinson, Thin-films field-transfer matrix theory of planar multilayer waveguides and reflection prism-loaded waveguides, J. Opt. Soc. Am. A, 1, 742-753 (1984). 

It is also necessary that there be an effective nonlinear coefiScient that couples the two modes. As I indicated earlier, poled polymer films and X- or Z-oriented LB films should have large fxx values that are optimum for interactions involving TM modes which contain components. By using multilayer waveguides, it is possible to devise approaches that avoid the spatial concentration of field distributions between low-order modes. One such approach is illustrated in Figure 6.18, with X- or Z-deposited LB films. In this figure, the polar orientation is reversed at the node of the TM mode. 

Rikken, G. L. J. A., Wavelength-uncritical second-harmonic generation in multilayer waveguides. Opt. Lett., 18, 1916-1918 (1993). 

Heinamad, A., Honkanen, S. (1989) "Non-linear waves in a multilayer waveguide application to SiOxNy with organic overlayer.". Opt. Quant. Electr. 21,137-146. 

Chemical properties of deposited monolayers have been studied in various ways. The degree of ionization of a substituted coumarin film deposited on quartz was determined as a function of the pH of a solution in contact with the film, from which comparison with Gouy-Chapman theory (see Section V-2) could be made [151]. Several studies have been made of the UV-induced polymerization of monolayers (as well as of multilayers) of diacetylene amphiphiles (see Refs. 168, 169). Excitation energy transfer has been observed in a mixed monolayer of donor and acceptor molecules in stearic acid [170]. Electrical properties have been of interest, particularly the possibility that a suitably asymmetric film might be a unidirectional conductor, that is, a rectifier (see Refs. 171, 172). Optical properties of interest include the ability to make planar optical waveguides of thick LB films [173, 174]. 

Studies of the waveguiding of light in multilayers of certain polymers showed that it is possible to propagate light with an attenuation that is still large compared to many other materials but small compared to other LB materials... 

W. H. Butler, X.-G. Zhang, D. M. C. Nicholson, T. C. Schulthess, and J. M. MacLaren, Giant Magnetoresistance from an Elecuon Waveguide Effect in Cobalt-Copper Multilayers , Physical Review Letters 76, pp.3216-3219, (1996). 

In recent years, the measurement of thick adlayers has received an increasing interest in the field of so-called polyelectrolyte multilayer films. These films sometimes have a thickness of several micrometers. Such large thicknesses are obviously not easily monitored using conventional waveguide sensors because of the limited penetration depth into the adlayer. Simply, waveguide sensors loses their sensitivity when the adsorbed layer thickness exceeds 2 3 times the penetration depth of the evanescent field and cannot be used to monitor films thicker than 350 nm12. 

Multilayer Langmuir-Blodgett films doped with a cyanine dye have been deposited on the surface of a quartz multimode optical fiber and the fluorescence properties investigated. 49 The fluorescence intensity of the films was found to be a periodic function of the number of layers due to the waveguide properties of the films. 

Fig. 13 shows an example where data for an irregular struetured multilayer thin-film-filter (TFF) are imported into a waveguide design. A FDTD-simulation earned out in order to check the influence of the internal resonator-like strueture of the TFF onto the waveguide deviee shows a signifieant transversal shift for oblique incidence. This hinders symmetrical multi-port designs, but may be used for specific WDM functionality. ... 

Non-centrosymmetric Langmuir-Blodgett multilayers were also prepared by alternate deposition of nitrophenylhydrazone (dye FA06) and trimethylsilylcel-lulose (TMSC) [85]. Such waveguides had a relatively low loss of 3.5 dB cm 1 at 633 nm and the nonlinear material exhibited a reasonable of 19 pm V. With a fundamental wavelength of 1064 nm, a conversion efficiency of 10 4, corresponding to slope of the order of 10 8% W em 1 was demonstrated and further work was proposed to diminish the optical losses. 

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