Special Temperature Features of the Birefringence of Lithium Tetraborate Crystals

摘要

Using the Senarmont polarimetric method, the optical birefringence of lithium tetraborate crystals Li_2B_4O_7 in the 290-480 K range was measured. The steplike temperature dependence of birefringence, the thermal hysteresis, and the thermooptic memory effect were observed, which are most likely associated with the presence of incommensurate phase modulation in lithium tetraborate.