A new organic electrooptic crystal: 2,6-dibromo-N-methyl-4-nitroaniline (DBNMNA)

A new organic electrooptic crystal, 2,6-dibromo-N-methyl-4-nitroaniline, is reported. The crystal structure was determined by X-ray diffraction (orthorhombic, space group Fdd2, point group mm2, Z=16, a=11.745 AA, b=29.640 AA, c=10.807 AA). The refractive indexes were measured at several wavelengths between 500 and 1100 nm (at 632.8 nm, n/sub a/=1.90, n/sub b/=1.62, and n/sub c/=1.48) and fit the data to a single oscillator Sellmeier equation. A report is presented on measurements of the linear electrooptic effect, yielding the combined coefficients n/sub a//sup 3/r/sub 13/-n/sub c//sup 3/r/sub 33/, as well as the first known measurements of the quadratic electrooptic effect in an organic crystal, yielding the coefficients r/sub 42/ and r/sub 51/ at 514.5, 632.8, and 810 nm. Good agreement is found between the observed dispersion in the electrooptic coefficients and that predicted by the simple two-level dispersion model.<
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