Definition and expression of non-symmetric physical properties in space for uniaxial crystals

The anisotropic physical property is the most noteworthy feature of crystals.In this paper,the subscript change method is used to analyze the sign changes of different tensors describing physical properties in uniaxial crystals.The distribution of some physical properties in special point groups exhibits non-symmetry in eight quadrants,which should attract the attention of crystal research.The difference between the crystallographic and physical coordinate systems and the lack of crystal symmetry operations are considered to be the origins of the non-symmetry.To avoid ambiguities and difficulties in characterizing and applying crystal physical properties,eight quadrants in space should be clarified.Hence,we proposed the use of piezoelectric properties to define the positive direction of the optical coordinate axis prior to the research and applications of optical properties.

Space symmetry of effective physical constants for biaxial crystals

In eight quadrants,the positive and negative signs of tensor components describing physical properties of biaxial crystals have been given.The distributions of the physical properties described with different order tensors and their space symmetries have been discussed.These results show that the distributions of effective physical constants are symmetrical in the eight quadrants for the orthorhombic system,but there are two and four kinds of distributions for monoclinic and triclinic systems respectively.Thence,to avoid ambiguities and difficulties in characterizing and applying properties of biaxial crystals,we suggest that the really positive directions of the coordinate axes should be defined before the measurements of their physical properties and their device applications.

High laser damage threshold LiNa_(5)Mo_(9)O_(30) prism:for visible to mid-infrared range

In this study,an excellent polarization optical crystal LiNa_(5)Mo_(9)O_(30) with wide transmission range and high laser damage threshold was researched in detail.The laser damage threshold of the LiNa_(5)Mo_(9)O_(30) crystal was measured to be 2.64GW/cm^(2),which was the highest among polarized optical crystals.The birefringence in the range of 0.435-5μm was larger than 0.14,while the wedge angle between 31.94°and 32.12°would satisfy the application in this waveband.The extinction ratio of the fabricated prism with the wedge angel of 31.09°was larger than 15,000:1.The results show that the LiNa_(5)Mo_(9)O_(30) prism is an excellent polarization device,especially in the mid-infrared range and high-power applications.