Femtosecond Diode-Pumped Cr : Lisgaf Lasers

The design and performance of diode-pumped Cr : LiSGAF lasers mode-locked by Kerr-Iens mode-locking and a solid-state saturable absorber are described. The different regimes of operation of the laser mode-locked by the saturable absorber are discussed. Both lasers generate 100-fs pulses with average powers of 40 mW and low fluctuations

Novel metal-template assembled highly-functionalized cyanoporphyrazine ytterbium and vanadium complexes for potential photonic and optoelectronic applications

International audienceA novel facile synthetic route to the metal-template assembly of a tetrapyrrollic framework from tetracyanoethylene (TCNE) and tricyanovinylbenzene (TCNVB) structural units through reaction of TCNE and TCNVB with metal -sandwich complexes has been developed. The reactions occur under extremely mild conditions, the porphyrazine macrocycles being assembled in high yield from TCNE and TCNVB building-blocks by VO2+ or Yb3+-template synthesis. The redox behaviour of the novel complexes has been investigated. The vanadyl octacyanoporphyrazine complex was found to be a rare example of a highly-absorbing dye combining significant electron-acceptor properties with a band gap unusually narrow for an organic semiconductor (ca. 1.1 eV). The preparation is described of a novel highly emissive ytterbium complex with a proposed unusual structure obtained by reaction of TCNVB with bis(indenyl)ytterbium(II) in THF. The analytical, spectral and electrochemical investigations of the obtained ytterbium complex indicate it to be a binuclear adduct with Yb(TCNVB)3 species in which a single doubly-reduced TCNVB molecule bridges two Yb3+ cations. The formation of a disordered polynuclear coordination polymer network including a macrocyclic structure and metal cations bridged through the nitrile nitrogen atoms is proposed. The complex is readily soluble and is compatible with a variety of polymeric matrices giving doped polymeric glasses and films which are highly luminescent in the biologically relevant optical window covering the visible and near-infrared (NIR) range (640–1000 nm). In addition, doped polymeric glasses and films highly emissive at the telecommunication wavelength (1540 nm), including a composition consisting of the novel ytterbium complex and an equimolar ratio of the novel ytterbium complex and a per se non-luminescent erbium chelate, have been obtained. The complex is found to be an extraordinarily strong sensitizer of NIR Er3+ emission

Chromium-containing organometallic nanomaterials for non-linear optics

International audienceNovel nonlinear optical polymeric film-producing nanocomposites based on bis(arene)chromium complexes incorporated into a CN-containing matrix have been developed. Polymer-precursors were prepared by the reaction of Cr(EtnC6H6 n)2 (n = 1,2,3) with CN-containing vinyl monomers (acrylonitrile, crotononitrile or ethyl 2-cyanopropenoate). Extraordinarily high third-order nonlinear optical susceptibilities of the ultra-fast electronic type have been demonstrated at various wavelengths for polymer films prepared from these composites by using the Z-scan technique and the spectrally-resolved two-beam coupling method. A notable electro-optical response of the composite with an essential contribution of orientational effects was established. The electron-diffraction pattern in films and the presence of a non-zero electro-optical coefficient in the absence of an external poling field indicates the formation of self-organized structures. In CrPAN and [CrPAN]+TCNE–, a single Cr-C distance was found in the EXAFS data refinement, showing that the arene rings are parallel and symmetric as in bis(benzene)chromium. The Cr-C distances in these two materials are very similar to the 2.13 Angstroms in bis(benzene)chromium. In [CrPAN]+OH–, more than one metal-carbon distance was resolved, showing either that the two arene rings are at different distances from the metal, or that they are tilted rather than parallel

Chromium-containing organometallic self-organized materials for nanophotonics

Novel non-linear optical polymeric film-producing nanocomposites based on bis(arene)chromium complexes incorporated into CN-containing matrices have been developed. Measurements by the spectrally resolved two-beam coupling method with a femtosecond range of pulse widths (central wavelength 795-800 nm) confirmed that the test composites exhibited a significant cubic nonlinear optical susceptibility of the ultra-fast electronic type. An open aperture Z-scan of the polymer film at 1550 nm showed a value of 9 × 10¿19 cm3 W¿2 for the three-photon absorption coefficient. The electro-optical measurements of the polymer composite showed a high electro-optical response (r33.n3 = 4.245 pm V¿1 at modulation frequency 210 Hz and poling DC voltage 2.16 V). A significant enhancement of the signals with a decrease in modulation frequency was observed consistent with an essential contribution of orientation effects to the electro-optical response. The measurements in the absence of external electrical fields showed a natural anisotropy resulting from self-organization taking place during the film formation process as confirmed by electron diffraction studies. A single Cr-C distance was found in the EXAFS data refinement, showing that the arene rings are parallel and symmetric as in bis(benzene) chromium