Optical materials nonlinear constants

Assessing thermal and photochemical stability is important. Thermal stability can be readily measured by measuring properties such as second harmonic generation as a function of heating at a constant rate (e.g., 4-10 °C/min) [121]. The temperature at which second-order optical nonlinearity is first observed to decrease is taken as defining the thermal stability of the material [2,3,5,63,63]. It is important to understand that the loss of second-order nonlinear optical activity measured in such experiments is not due to chemical decomposition of the electro-optic material but rather is due to relaxation of poling-induced acentric... 

Optical materials refractive index n (to) n (2nonlinear optical constant d hi xlO (esu) 2nd-order molecular polarizability 0 xlO 30 (esu) 3rd-order nonlinear susceptibility X xlO 14 (esu)... 

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 ... 

The interest in efficient optical frequency doubling has stimulated a search for new nonlinear materials. Kurtz 316) has reported a systematic approach for finding nonlinear crystalline solids, based on the use of the anharmonic oscillator model in conjunction with Miller s rule to estimate the SHG and electro optic coefficients of a material. This empirical rule states that the ratio of the nonlinear optical susceptibility to the product of the linear susceptibilities is a parameter which is nearly constant for a wide variety of inorganic solids. Using this empirical fact, one can arrive at an expression for the nonlinear coefficients that involves only the linear susceptibilities and known material constants. 

This review summarizes the current state of materials development in nonlinear optics. The relevant properties and important materials constants of current commercial, and new, promising, inorganic and organic molecular and polymeric materials with potential in second and third order NLO applications are presented. 

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