Absolute measurement of the second-harmonic generation nonlinear susceptibility of tellurium at 28.0 µm

The second-harmonic generation nonlinear optical susceptibility of trigonal tellurium has been measured at 28.0 μm by the phase-matching technique. The value obtained was
|d_{11}| = (5.7 \pm 1.9) \cdot 10^{-10}
m/V in MKS units. This value establishes the longest wavelength "standard" for the measurement of nonlinear optical susceptibilities by comparative techniques. Experimental details and data are given to justify the quoted uncertainty.