Computer simulations of the measurement of quadratic electro-optic coefficients associated with rotations of the principal axes of the optical permittivity tensor

摘要

Certain quadratic electro-optic coefficients may be measured in more than one configuration of a light path and an applied field. An example is the coefficient g_(xyxy) of potassium dihydrogen phosphate (KDP), which can be determined, for the same field, with the light either along the optic axis or perpendicular to it, albeit in the latter case in combination with other electro-optic coefficients. This field in KDP produces a rotation of the principal axes of the optical-frequency permittivity tensor. Computer calculations show that the relative errors due to misalignment and imprecise cutting of a KDP crystal for a perpendicular light path are about 10~3 smaller than those found in an earlier investigation for similar deviations when the light was parallel to the optic axis. This suggests that where a given coefficient of a uniaxial crystal can be determined either perpendicularly or parallel to the optic axis, the former configuration should be chosen, especially if the electric field produces a rotation of the principal axes of the permittivity tensor.