Piezooptic Dispersion of Li2Ge7015 Crystals

The piezooptic dispersion of the ferroelectric crystal Li2Ge7015 (LGO) was studied in the visible region of the spectrum at room temperatures between 278 K and 298 K. The results show an interesting photoelastic behavior. The piezooptic coefficient C decreases with wavelength in the visible region up to a certain wavelength and then it shows a peak at sodium yellow wavelength and later on the usual reduction is observed. Thus there seems an optical zone in between 5400 and 6200 with an enhanced piezooptical behavior. This enhancement is observed to be very high, as high as 50%, when the crystal is stressesd along [001] and observation made along [100]. The height of this region is different for different orientations, though the width seems approximately the same.