publication detail
Molecular Engineering for Quadratic Nonlinear Optics : the Role of Metal Complexes
AUTHORS
Document type
Conference papers
Résumé
The emergence of Molecular Photonics at the cross-road of physics, chemistry and device engineering is triggered by the increasing demands in the domain of high bit rate telecommunications and of sensor applications. The wealth of molecular structures and the exploitation of their functional and structural flexibility open-up thoroughly renewed horizons in this domain. In this talk we will report on the interest of transition metal and lanthanide complexes in molecular engineering for quadratic nonlinear optics (NLO), with a focus on multifunctional properties such as photochromism and light amplification in the telecommunication domain. An example on efficient tuning of molecular NLO properties is illustrated by dithienylethene (DTE) photochromic metal complexes, which display photo-induced switching properties for both octupolar (tetrahedral and octahedral) and dipolar complexes. A highly efficient photo-triggered NLO enhancement (up to 50) from the “open” to the “closed” forms has been reported, with a significant influence of the donor end group of the photoswitchable ligands and of the nature of the central metal ion on the NLO molecular response. Lanthanide complexes are also interesting structures for NLO applications. Noncentrosymmetric dipolar and octupolar complexes based on different lanthanide ions involving an increasing number of f-electrons are shown to display a linear dependence of their hyperpolarisability values with the number of f electrons. We also focused on Phthalocyanines (Pc) sandwich-type complexes with various lanthanide ions holding two Pc macrocycles closer than their van der Waals distance, resulting in strong pi-pi interactions and through-space three-dimensional delocalization. Huge quadratic hyperpolarizabilities (up to 5.10-27 esu) have been measured using Harmonic Light Scattering measurements at 1.9 µm. An example of possible applications of lanthanide complexes has been evidenced using erbium-organic complexes in polymethylmethacrylate PMMA polymer matrices and waveguides displaying near infra-red (IR) luminescence and gain. Gain coefficients values reaching reasonable values (0.9 cm-1) have been obtained for an erbium complex-doped PMMA matrix at the 1.55 µm telecom wavelength, and a positive net gain of 0.9 dB/cm has been evidenced in a single mode erbium-doped polymer-based rib waveguide under 980 nm pumping.