SOLUTION CRYSTAL-GROWTH OF UREA AND DERIVATIVES FOR NONLINEAR-OPTICALAPPLICATIONS

Urea is an excellent nonlinear optical (NLO) medium. However, growth o f large high-quality crystals for practical use still remains a challe nge due to its unfavourable growth properties. Improved crystalline an d optical quality could be expected in derivatives of urea. In this co ntribution we report on the growth of urea and its derivatives: monome thylurea (NMU), 1,1-dimethylurea (1,1-DMU), and 1,3-dimethylurea (1,3- DMU). Satisfactory quality and reasonable size of both urea and monome thylurea crystals have been achieved. Some evaluation of the quality o f the grown crystals is reported. This work shows that NMU exhibits a better crystal habit than urea does, while preserving almost the same transparency window. This would suggest that NMU is a potentially prom ising material in nonlinear optical applications.