Piezooptic Dispersion of Li₂Ge₇0₁₅ Crystals

Abstract

The piezooptic dispersion of the ferroelectric crystal Li ₂ Ge ₇ 0 ₁₅ (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_λ 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 Å and 6200 Å 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.

Keywords:

• Ferroelectrics
• optical properties
• nonlinear optics

Acknowledgments

The authors thank Professor R. Ethiraj and G.S. Kumar for many useful discussions and suggestions. One of the authors (A.K.B) is thankful to the Government of India for providing the research fellowship under Indian Council for Cultural Relations (ICCR).