Design of Polymethine Dyes with Large Third-Order Optical Nonlinearities and Loss Figures of Merit

Abstract

All-optical switching applications require materials with large third-order nonlinearities and low nonlinear optical losses. We present a design approach that involves enhancing the real part of the third-order polarizability (gamma) of cyanine-like molecules through incorporation of polarizable chalcogen atoms into terminal groups, while controlling the molecular length to obtain favorable one- and two-photon absorption resonances that lead to suitably low optical loss and appreciable dispersion enhancement of the real part of gamma. We implemented this strategy in a soluble bis(selenopyrylium) heptamethine dye that exhibits a real part of gamma that is exceptionally large throughout the wavelength range used for telecommunications, and an imaginary part of gamma, a measure of nonlinear loss, that is smaller by two orders of magnitude. This combination is critical in enabling low-power, high-contrast optical switching.

Optoelectronic and photoacoustic studies of an organic dye synthesized through green route

“…The ground state absorption cross-section, g  is calculated from the equation, α=σgNaC; where Na is the Avogadro's number and C is the concentration in moles/cm 3 . The measured value of σex is 1.55×10 -18 cm 2 which is found to be larger than the value of σg, 1.32×10 -19 cm 2 .…”

“…They absorbs light in the visible spectrum (400-700 nm) and exhibit resonance of electrons, which is a stabilizing force in organic compounds. The nonlinearity of these molecules has been found to originate from a strong delocalization of π-electrons along the length of the molecule [3]. Apart from the established applications of azobenzene molecules recently they have recently been considered as an alternative material for use in dye-sensitized solar cells [4].…”

Crystal structure of the chalcogen-containing precursors for polymethine dyes

“…1 However, in order for these materials to retain their favorable solution properties in the high-number density films, their molecular aggregation should be reduced. To limit aggregation, bulky groups may be introduced in several positions of the dye to protect the π-conjugated system from interacting with itself.…”

Integrated optical application of bacteriorhodopsin

“…So far, specifically designed organic, pi-conjugated molecular materials have attracted the most interest [3,4], but their applicability in IO is still to be verified. Although biological materials are often disregarded in technical applications, there are several proteins that are extremely robust, so their biological origin doesn't represent a disadvantage, on the contrary, they offer special advantages to be exploited in bioelectronic applications [5].…”

“…4 [28,[30][31][32][33][34][35]. The late intermediate states are also photosensitive, the photocycle can be short-cut at any step by applying a second flash exciting the corresponding intermediate state [36,37].…”