Torsion induced giant gyrotropy in hexagonal CdS and CdSe crystals

The undeformed hexagonal CdS and CdSe crystals (symmetry C6v) manifest “weak” gyrotropy. A strong gyrotropic effect is measured in crystals of CdS and CdSe deformed by torsional moment directed along the optical axis. The standard system Polarizer-Crystal-Analyzer (P-C-A) is used. The system (P–C-A) with crossed P and A, and undeformed CdS or CdSe crystal does not transmit light. The torsion reduces the crystal symmetry to C6 and the crystal receives gyrotropic properties. The system (P-C-A) with deformed CdS or CdSe crystal begins to miss light. Our investigations show that for large values of the torsional moments the intensity of the light, which passed through the system (P–C-A) with deformed CdS or CdSe crystal, is 85-90% from the incident light intensity. The induced gyrotropy can be considered as giant on the basis of this experimental fact.