Optical isolators in YAG:Nd laser cavities

The Jones matrix technique is used to calculate losses due to optical isolators in laser cavities with a linear phase anisotropy. The behavior of YAG:Nd lasers when the cavity is tuned, when the pump power changes, or when a nonlinear frequency-doubling crystal is inserted inside the cavity, is explained by considering the effects of a phase plate, and practical recommendations for designing optical isolators are formulated. In particular, the calculated results can be used to find tolerances on the alignment of the polarizer and the principal axes of the nonlinear crystal. It is also shown that a half-wave plate must be used to rotate the polarization plane for optimum performance of optical isolators in YAG:Nd laser cavities.