A 160-Femtosecond Optical Image Processor Based on a Conjugated Polymer

Abstract

Degenerate ground-state conjugated polymers exhibit large third-order nonlinear optical susceptibilities, including substantial two-photon absorption. With the use of a machine architecture suited to these material properties, ultrafast optical processors are possible. A four-wave mixing optical correlator was built with an air-stable, processable, degenerate ground-state conjugated polymer, poly(1,6-heptadiester). The continuously updatable processor correlates two 5000-pixel images in less than 160 femtoseconds, achieving peak processing rates of 3 x 10(16) operations per second.

Thick Optical‐Quality Films of Substituted Polyacetylenes with Large, Ultrafast Third‐Order Nonlinearities and Application to Image Correlation

“…It has long been known that DFWM can be exploited to perform image recognition. [35] Furthermore, employing a material with an ultrafast nonlinearity allows for the possibility of extremely rapid optical pattern recognition, which could play a significant role in the development of security verification, [36] facial recognition, [2] and artificial intelligence in general. The success of this application is predicated on a large diffraction efficiency which itself is dependent on the drive intensity, sample length, and material nonlinearity.…”

“…The success of this application is predicated on a large diffraction efficiency which itself is dependent on the drive intensity, sample length, and material nonlinearity. [2] Facile processing through ROMP using initiator 3 (chosen for the superior optical quality of the resulting films) permitted fabrication of 200 mm thick poly(-n-butyl-COT) films which, in the DFWM geometry, were found to generate substantial diffraction efficiencies at moderate drive intensities using off-resonant excitation: $0.1% at 100 MWcm À2 for 1300 nm and $1% at 1 GW cm À2 for 1550 nm. These results represent sizable improvements compared to other conjugated polymers [2] that have been used for DFWM, due in part to both the large nonlinearity and increased interaction length of the poly(n-butyl-COT) films.…”

“…[1][2][3][4] Conjugated polymers, such as polyacetylene, have been shown to exhibit large optical nonlinearities upon application of intense electromagnetic fields.…”

“…[1][2][3][4] Conjugated polymers, such as polyacetylene, have been shown to exhibit large optical nonlinearities upon application of intense electromagnetic fields.[3] Despite these nonlinearities, many conjugated polymers are inadequate for photonic applications because they lack sufficient processability, or form films with significant crystallinity [5] or inhomogeneous morphologies [6] resulting in poor optical quality. For example, although films of unsubstituted polyacetylene have been found to possess large third-order susceptibilities, [7][8][9] they also exhibit extensive crystallinity, [10] resulting in poor optical quality and large scattering losses.…”

“…These jx (3) j values compare favorably with nonresonant nonlinearities for other conjugated polymers. [2,32] Furthermore, the dispersion of the nonlinearity was determined in the NIR using the Z-scan method and the values of the magnitude and phase [33] of x (3) for a representative film are shown in Table 1.…”