Off-resonant electric field induced second harmonic generation (EFISH) and resonant third harmonic generation (THG) measurements of two squarylium dyes are reported. The magnitude of is large for both processes. The EFISH measurement clearly shows that the off-resonant third-order polarizability is negative, a consequence of the dominance of a non-two-photon mechanism. This unusual result is in agreement with our earlier reports on two other squarylium dyes. Resonant THG measurements strongly suggest that the two-photon contribution, while smaller than the one-photon contribution, is not negligible and cannot be entirely ignored when defining the overall thirdorder optical susceptibility. Consequently, the squaryliums are best qualitatively described by a three-level model that truncates to two dominant perturbation terms. Also reported is the isomeric distribution of squaryliums. Proton NMR results are interpreted by way of molecular mechanics to show that the squaryliums can readily exist as a mixture of isomers. The possible effects on nonlinear optical (NLO) measurements via an orientational contribution to the EFISH are discussed. An X-ray structure for the squarylium dye TSQ is presented and interpreted. The X-ray structure clearly suggests that the squarylium dyes are extensively bond delocalized with relatively little bond length alternation.

Systems-on-Chip (SoC) and Systems-on-Package (SoP)

One of the most promising applications of MOEMS in Optical Networks is represented by free-space electro-mechanical Optical Cross-Connects (OXCs); these components show lower attenuation and lower insertion losses than concurrent components based on waveguides. Although some commercial micromachined electro-mechanical OXCs have been recently announced in the market, further deployment of these devices will certainly require decreasing insertion losses by proper design techniques of both, the electromechanical devices and the system packaging.In this document, we study insertion losses in micromachined free-space OXCs and the related packaging challenges; we assume in our discussions Single Mode Fiber (SMF) Cross-Connects using mirrors as beam steering devices. We start with an introduction to micromachined OXCs architectures, actuation mechanisms and collimators. In section 2, we present a study of insertion losses in SMFs links; the coupled effect of lateral and angular fiber misalignments is discussed. In section 3, we discuss insertion losses in OXCs when quarter-pitch GRIN lenses are used as fiber collimators; both sections 2 and 3 are based on Gaussian beam optics. In section 4, we explore the application of Scalar Diffraction Theory to OXC design, this is for calculating insertion losses including diffraction at the mirror plane. Finally, conclusions on insertion losses and the required fiber positioning accuracy are given.

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Abstract