All-optical processing

Besides W, there are two other definitions of FOM for all-optical processing ... 

As was proven later by Bishop [19], the coefficient A in the expansion (73) is the same for all optical processes. If the expansion (73) is extended to fourth-order [4,19] by adding the term the coefficient B is the same for the dc-Kerr effect and for electric field induced second-harmonic generation, but other fourth powers of the frequencies than are in general needed to represent the frequency-dependence of 7 with process-independent dispersion coefficients [19]. Bishop and De Kee [20] proposed recently for the all-diagonal components yaaaa the expansion... 

Other applications that were recently demonstrated with photorefractive polymers include homodyne detection of ultrasonic surface displacements using two-wave mixing [115]. With the development of new photorefractive polymers with response times in the millisecond range, numerous optical processing techniques can be performed at video rates. Image amplification and novelty filtering at video rates were demonstrated recently [116]. All-optical processing techniques compete with computational methods. Therefore, it is important that photorefractive polymers exhibit faster response times in the future. 

Some of these specialized nonlinear all-optical processes have been discussed in the preceding sections and the hterature quoted thereia Since these nematic Uqnid crystals possess extremely high nonlinear index change coeffidenL they reqnire no external bias, and function at much lower optical powers and shorter exposnre times than other conventional methods. " Here we discnss more exemplary cases. 

In an effort to identify materials appropriate for the appHcation of third-order optical nonlinearity, several figures of merit (EOM) have been defined (1—r5,r51—r53). Parallel all-optical (Kerr effect) switching and processing involve the focusing of many images onto a nonlinear slab where the transmissive... 

These effective frequencies are chosen such that contributes only for optical processes with at least three non-zero frequency arguments, while u 4 is only non-zero if all four frequency arguments are non-zero. During the implementation it was also found that this choice for the effective frequencies leads to the most compact expressions for the coefficients Ak,i,m in terms of D n,m,l). Using a similar notation as in Eq. (73), 7 (o o Wi,o 2i 3) can up to sixth order in the frequencies be expanded... 

Hales JM, Zheng S, Barlow S, Marder SR, Perry JW (2006) Bisdioxaborine polymethines with large third-order nonlinearities for all-optical signal processing. J Am Chem Soc 128 11362-11363... 

The third order nonlinear susceptibility is an important optical property of materials because of its contributions to numerous nonlinear optical processes. (1)(2) With the growing interest in all-op ical signal processing it has been proposed (3) recently that x ( 1, 2 3) and especially the degenerate third order nonlinear susceptibility x 3 (-w, to, 00) [defined as x (< >)], be utilized through its contributions to the changes in dielectric constant e with optical field strength E ... 

Up to now, many conjugated polymers have been found to possess large and very rapid third-order nonlinear optical response, which originates from the one-dimensionally delocalized ji-conjugation system along the polymer chain. Their application to the all optical signal processing devices has been expected. 

M. M. Fejer. Quasi-phasematched for fiequency conversion and all optical signal processing (short course 1260) in Conference on Lasers and Electro-Optics, Baltimore (2001). 

Common characteristics of all viable process Raman instmments include the ability to measure at multiple locations, simultaneously or sequentially, and in a variety of electrically classified or challenging environments with no special utilities. The instrument must be reasonably rugged and compact, and not require much attention, servicing, or calibration [19]. Modem process Raman instruments essentially are turnkey systems. It is no longer necessary to understand the optical properties and other instrnment details to suc-cessfnlly nse the techniqne. The general design options will be described briefly, bnt more information is available elsewhere [20,21]. This section will focus primarily on special instrumentation considerations for process installations. 

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