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Abstract:The requirement for materials which exhibit good second and third order non-linear optical properties and also for materials which could sense metals in trace quantities has kindled renewed investigations. Organometallics and coordination compounds show a lot of promise as new NLO materials combining the variety of organic moieties with the strength and variable oxidation states of metals. Especially ligands which selectively detect industrial pollutants like Cd and biologically significant metals like Zn are necessary. In the current work the ligand 1,10-phenanthroline-2,9-di(carboxaldehyde phenylhydrazone) (L) and its Ni 2+ , Co 2+ , Fe 2+ , Zn 2+ , Cd 2+ and Ir 3+ complexes were synthesized. These were characterized by UV-Vis, FT-IR, 1 H NMR, MS and CHN microanalysis techniques. The complexes were shown to have the formula [ML] 2+ . The second and third order NLO of the ligand and its complexes were recorded These new compounds were found to have same order of third order nonlinear optical susceptibility as that of CS 2 and their second hyperpolarizability was an order of magnitude greater than that of C 60 . Furthermore the ligand also displays selective luminescence sensing of metals ions Fe 2+ and Ir 3+ even in the presence of other metal ions.Keywords: Transition metal complexes, 1, 10-Phenanthroline-2, 9-dialdehyde, Second Harmonic Generation (SHG), DFWM, Luminescence IntroductionThe development of the first laser by Miamen in 1960 laid the cornerstone for the development of the field of nonlinear optics as we know it now [1]. There is a great demand for organic molecules which exhibit nonlinear optical (NLO) properties due to the large hyperpolarizability and inherent freedom of synthesis which they offer [2]. The presence of push and pull π-conjugation confers upon organic molecules high values of second order polarizability [3]. It has to be noted that SHG is exhibited only by noncentrosymmetric crystals. A few organic compounds which crystallize in noncentrosymmetric structures give good optical quality crystals [4] but the presence of only organic moieties lack the mechanical strength that is required for practical purposes [5]. Thus with the objective of building closely-knit crystalline structures, the crystal engineering strategy of combining organic and inorganic moieties was introduced [6].There have been several examples in these hybrid organic-inorganic moieties which exhibited good NLO properties [7][8][9][10]. Among these materials, organometallics and coordination compounds have been promising due to the variations they introduce in the nature, the oxidation state and coordination sphere of the metal ion and also due to the changes the metal ion brings about in the coordinating ligands [11][12][13][14][15][16][17][18]. Thus, the coordination of a metal ion to a ligand with conjugated π-system may increase the hyperpolarizability γ as a result of very extensive delocalization of electrons and polarizability. In this context, the ligand 1, 10-phenanthroline (phen) Abstract: In th...

We evaluate the construction and performance of an ultra-low-cost full-field optical coherence tomography (FF-OCT) instrument, also known as an optical coherence microscope. Although the cost of construction of the instrument from off-the-shelf parts is at least ten times lower than those of commercial products, sub-4-micron axial and lateral resolutions are obtained, albeit at the cost of higher acquisition times. Standard test samples are imaged and the performance of the instrument is evaluated. The device is found to be useful in measuring length, dispersion and group refractive index as well. Suggestions for bettering performance are discussed.

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The authors propose a resonant loop mirror configuration using two couplers and a weak reflecting element in the feedback arm. The analysis is carried out using the signal flow graph method. Narrow band reflection peaks can be produced using a wide choice of parameters. A Vernier effect in the two loops can lead to a tenfold increase in the free spectral range. These properties make the device more versatile than the earlier studied single coupler resonator with “reflector” and enhance its use in single frequency lasing.