Poled film second harmonic generation

The second-order nonlinear optical properties of the poled film are investigated using second harmonic generation in transmission. The sample preparation technique results in a poled glassy film possessing a unique axis in the direction parallel to the field direction within... 

Mortazavi, M. A., Knoesen, A., Kowel, S. T., Higgins, B. G., and Dienes, A. Second-harmonic generation and absorption studies of polymer-dye films oriented by corona-onset poling at elevated temperatures. Journal of the Optical Society of America B Optical Physics), vol. 6, (no. 4), April 1989, pp. 733-741. 

Figure 6.7. Upper linUts of x values reported for second harmonic generation of poled polymers, crystals, and LB films compared with those of inorganic crystals. Also noted is x /or the linear electrooptic effect in LiNbOa-...

The second harmonic generation is a coherent technique giving the fast, electronic in origin, second-order NLO susceptibility (-2co co,co) at a given, measurement frequency co. Here, we limit the discussion to poled films, with °o mm symmetry, which exhibit two nonzero x tensor components the diagonal A zzz( 2co co,co) and the off diagonal xzz( 2co co,co), where Z is the poling (preferential orientation) direction. Usually, thin films are deposited on one side of substrate only (thin film deposited on both sides is discussed in Swalen and Kaj-... 

In addition to nitro derivatives, polyphosphazenes with sulfonyl-based chro-mophores (259) and (260) have been prepared according to a post-azo coupling approach with 4-ethylsulfonylbenzenediazonium fluoroborate. Absorptions of these polymers are blue-shifted compared to the absorptions of the nitro analogues. NLO activities of poled films of (259) and (260) have been determined by second harmonic generation measurements. " ... 

Two triphenylamino-substituted chromophores with and without hydroxyl end, named TIOH and Tl (Figure 6.7), respectively, were synthesized and incorporated into hybrid organic-inorganic materials derived from 3-glydoxypropyltrimethoxysi-lane, tetraethoxysilane, and 3-aminopropyltriethoxysilane [54]. These stilbene-type chromophores were characterized by elemental analysis by NMR, FT-IR, UV-vis spectra, and TGA. The hyperpolarizabilities were characterized through solvato-chromic method. Both chromophores possessed higher thermal stability and competitive hyperpolarizabilities. Second harmonic generation was observed on poled films. The nonlinear coefficient of the samples was established at 41.2 pm/V for TIOFJ doped film and at 24.8 pm/V for Tl doped film. 

Also, Zhu and coworkers reported preparing of two high Tg (250° and 258°) polyimides embedded with triphenyl imidazole chromophores. Simultaneous polymerization and poling was carried in situ. The second harmonic generation measurements technology yielded moderate das values of 15 pnW and 16 pnvV. The signals of these poled polymer films were reported to be without any decay at < 150° The relaxation starts rapidly over 195°. The half-decay temperatures, of the samples orientation are as high as 240° and 224° respectively. 

Cooper, T. M., Stone, M. O., Obermeier, K., Crane, R., Epling, R., Tokarski, Z., and Natarajan, L. V., Second harmonic generation in corona poled thin films of spiropyran-modified succinylated poiy(L-lysine), Polym. Prepr., 34, 598-599 (1993). 

Recently, a polymer thin film doped with a chiral almost centrosymmetric bisazo-molecule has been demonstrated to exhibit second harmonic generation after all-optical poling [64]. 

Singer KD, Sohn JE et al (1986) Second harmonic generation in poled polymer films. Appl Phys Lett 49(5) 248-250... 

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