Improved optical quality of crosslinkable nonlinear polymer waveguides by anchoring the diffusive small molecules

1(b)] , a r33 value of 13 pm/V at 633 nm was achieved and a long-term stability at 1257C is proved through Using nonlinear optical (NLO) polymeric materials to annealing a sample at this temperature for over 1250 h. fabricate electrooptic (EO) devices has several well-recIt is both technically and commercially interesting to ognized advantages such as compatibility with different use crosslinkable NLO polymer to fabricate EO devices. substrates, ease of fabrication, and possibly low costs However, only very few materials have been reportedly compared with the inorganic counter parts such as lithused in making any kind of useful devices. The ium niobate. As a result, a lot of NLO polymers have excellent stability and the good EO coefficients make been synthesized in recent years. However, the progLD-3 polymer an ideal candidate for fabrication of EO ress of the fabrication of practical devices has been impolymer devices, but some unsolved processing probpeded by the lack of processability of the materials. A lems with this material impede the progress of its praclow loss waveguide with a high and stable NLO coeffitical application. Even some researchers who first pubcient is needed for any practical device. Polyimide NLO lished this material turn their attention to other matematerials offer the best stability; however, the NLO rials which have much inferior stability. The active materials have relatively high optical losses (ú3 PURDR19 is most frequently used to fabricate wavedB/cm) and it is often the case that the losses and guide devices. Test devices made of other two materiprocessability remain unreported. Other materials, als BIN2-HDT and Red-acid Magly are also reported however, do not possess a thermal stability satisfying by other researchers. However, BIN2-HDT, PURDR19 commercial or military requirements. Much higher and Red-acid Magly have long term stabilities only up stability can be achieved by crosslinking both of the to 100, 90, and 857C, respectively. ends of a NLO chromophore into the polymer network. It is significant if the processing problems of LD-3 Although many efforts have been made, only a few NLO can be solved because its superior stability allows a materials have achieved long term stabilities near or much wider range of applications. More importantly, up to 1007C, and one material (LD-3) turns out to some insight into these problems might also apply to have a long term thermal stability satisfying the miliother crosslinkable NLO polymer systems. The key part tary requirement of 1257C. LD-3 is a thermally crossof fabricating LD-3–based NLO polymer devices is the linkable NLO polymer consisting of a poly (methyl preparation of the NLO polymer films. For a crossmethacrylate) (PMMA) backbone and an azobenzenelinkable polymer, we need to first dissolve the polymer sulfone chromophore [Fig. 1(a)] . It can be crosslinked and the crosslinker together to make a spin-coatable by a diisocyanate crosslinker. Using Dianisidine diisosolution. Then the chromophores need to be aligned