Optical waveguide amplifiers based on polymer materials offer a low-cost alternative for inorganic waveguide amplifiers. Due to the fact that their refractive index is similar to that of standard optical fibers, they can be easily coupled to existing fibers with low coupling losses. Doping the polymer with rare-earth ions that yield optical gain is not straightforward, as the rare-earth salts are poorly soluble in the polymer matrix. This review article focuses on two different approaches to dope a polymer waveguide with rare-earth ions. The first approach is based on organic cage-like complexes that encapsulate the rare-earth ion and are designed to provide coordination sites to bind the rare-earth ion and to shield it from the surrounding matrix. These complexes also offer the possibility of attaching a highly absorbing antenna group, which increases the pump efficiency significantly. The second approach to fabricate rare-earth doped polymer waveguides is obtained by combining the excellent properties of SiO 2 as a host for rare-earth ions with the easy processing of polymers. This is done by doping polymers with Er-doped silica colloidal spheres.

m-Terphenyl-based lanthanide complexes functionalized with a triphenylene antenna chromophore ((Ln)1) exhibit sensitized visible and near-infrared emission upon photoexcitation of the triphenylene antenna at 310 nm. Luminescence lifetime measurements of the (Eu)1 and (Tb)1 complexes in methanol-h 1 and methanol-d 1 revealed that one methanol molecule is coordinated to the lanthanide ion, indicating that all eight donor atoms provided by the ligand are involved in the encapsulation of the lanthanide ion. The luminescence lifetimes of the near-IR-emitting complexes (Er)1, (Nd)1, and (Yb)1 in DMSO-h 6 and DMSO-d 6 are in the microsecond range, and are dominated by nonradiative deactivation of the luminescent state. The processes preceding the lanthanide luminescence in the sensitization process have been studied in detail. The complexed lanthanide ion reduces the antenna fluorescence and increases the intersystem crossing rate via an external heavy atom effect. The subsequent energy-transfer process was found to take place via the antenna triplet state in all complexes. Luminescence quantum yield measurements and transient absorption spectroscopy indicated that in solution two conformational isomers of the complexes exist: one in which no energy transfer takes place, and one in which the energy transfer does take place, resulting in the lanthanide luminescence. The intramolecular energy-transfer rate is higher in the (Eu)1 and (Tb)1 complexes than in the near-infraredemitting complexes. In methanol the energy-transfer rate is 3.8 × 10 7 s -1 for (Eu)1 and (Tb)1. In DMSO-d 6 the intramolecular energy-transfer rate is higher in the (Nd)1 complex (1.3 × 10 7 s -1 ) than in the (Er)1 (3.8 × 10 6 s -1 ) and (Yb)1 (4.9 × 10 6 s -1 ) complexes.

Data visualization plays a crucial role in our society, as illustrated by the many displays that surround us. In the future, displays may become even more pervasive, ranging from individually addressable image-rendering wall hangings to data displays integrated in clothes. Liquid-crystal displays (LCDs) provide most of the flat-panel displays currently used. To keep pace with the ever-increasing possibilities afforded by developments in information technology, we need to develop manufacturing processes that will make LCDs cheaper and larger, with more freedom in design. Existing batch processes for making and filling LCD cells are relatively expensive, with size and shape limitations. Here we report a cost-effective, single-substrate technique in which a coated film is transformed into a polymer-covered liquid-crystal layer. This approach is based on photo-enforced stratification: a two-step photopolymerization-induced phase separation of a liquid-crystal blend and a polymer precursor. The process leads to the formation of micrometre-sized containers filled with a switchable liquid-crystal phase. In this way, displays can be produced on a variety of substrates using current coating technology. The developed process may be an important step towards new technologies such as 'display-on-anything' and 'paintable displays'.

Energy transfer (ET) from ferrocene or ruthenium tris(bipyridine) functionalized light‐harvesting units allows the first observation of sensitized near‐infrared (NIR) lanthanide (Ln) luminescence (Lum.; see scheme, Exc.=excitation). Since the donating triplet state of the ruthenium tris(bipyridine) antenna is luminescent, the sensitization process could be studied in detail.