The efficient two-photon absorption of certain chromophores can be used to extend photodynamic therapy to the near infrared spectral region. Whereas the photosensitizer itself may not exhibit two-photon absorption, it could be used in conjunction with one of these new chromophores. The chromophores can act as "photon harvesters" whereby they absorb two photons of near infrared light and transfer the energy to the photosensitizer, which can generate singlet oxygen in the presence of atmospheric oxygen.

Sol-gel-derived glasses have emerged as a new class of materials well suited for the immobilization of biomolecules. As a consequence, they are also finding new applications as platforms for chemical sensors. Room temperature (or lower) processing conditions, chemical inertness, negligible swelling effects, tunable porosity, and the high purity of sol-gel-derived glasses make them ideal for many types of sensor applications. We

We present the preparation of novel multifunctional nanostructured composite materials using the sol-gel process. We have demonstrated the doping of two optical limiting organic molecules (Cso and bisbenzothiazole 3,4-didecyloxythiophene (BBTDOT)) in a single bulk while maintained the optical limiting effect at each of their characteristic wavelengths. A multiphasic composite glass doped with both Cso and BBTDOT exhibited effective optical power limiting at 532 and 800 nm due to independent limiting effects at each wavelength generated by each of the two dopants. These composite glasses have excellent optical quality (loss % 1 dB/m) and a large bulk size. By using our methodology, it is possible to dope two (or more) different optically responsive materials, each of which will reside in different phases of the matrix to make multifunctional nanostructured bulk materials for photonic applications.

No abstract

There is a great deal of interest in developing π-conjugated polymeric semiconductor based diode lasers which can yield lasing under electrical excitation. Towards this goal, tunable cavity lasing was achieved in a poly(para-phenylene vinylene) derivative alternating block copolymer, BMPPV, dispersed in an active solid matrix of poly(9-vinylcarbazole), with which this block co-polymer also exhibits strong electroluminescence. The laser operated in the blue region of the spectrum over the range 480 to 510 nm, with an optical efficiency approaching 10%. Linewidth narrowing and a narrowing of the temporal profile are reported. Operating lifetime of the solid-state laser was in excess of 5000 pulses at the same pumping position on the sample. Lasing properties of the same block copolymer in the solution phase were also investigated and the results compared with the solid state laser performance.