Growth of large size high optical quality KTP-type crystals

Growth of large and optically uniform single crystals of KTiOPO4 (KTP) and its isomorphs is of great importance in laser frequency conversion applications. We have demonstrated that the size of the crystal must not be sacrificed in the quest for attaining high quality. The top-seeded solution growth from pure and modified self-fluxes with pulling on oriented seeds is found to be technologically preferable method for achieving this goal. The crystal properties are largely dependent on the solution chemical composition, and the latter must be properly selected with regard to the required crystal optical performance. Otherwise, the key to obtaining crystal with superior properties is the choice of seeding direction with respect to application. Thus pulling in the [1 0 0]-direction from K6P4O13− or Rb6P4O13− type solutions yield crystals with excellent optical uniformity within the (1 0 0) facet constituting the major part of the growth interface. Optical elements fabricated from such crystals (especially from RbTiOPO4) are most suitable for electro-optic Q-switching. Pulling of KTP crystals on [0 1 0] and [0 0 1]-oriented seeds, from self-fluxes of various compositions, is also discussed in terms of associated application, such as high-power frequency doubling of 1064 nm laser radiation into the green and preparation of periodically poled substrates for quasi-phase-matched blue laser operation.