Inorganic nonlinear optical crystal GdGa 4O(BO 3) 3(GdCOB) possesses moderate NLO efficient (1.3pm/V) ,high damage threshold(>1GW/cm 2),and wide transmission wave band(320-2700nm).In addition,it is chemically stabl...Inorganic nonlinear optical crystal GdGa 4O(BO 3) 3(GdCOB) possesses moderate NLO efficient (1.3pm/V) ,high damage threshold(>1GW/cm 2),and wide transmission wave band(320-2700nm).In addition,it is chemically stable,nonhygroscopic and easy to process,which makes GdCOB a promising practical NLO material for frequency conversion.Crack free single crystals of GdCOB with large size have been grown using the vertical Bridgman method for the first time.Stoichiometric amounts of starting materials 4N pure Gd 3O 3,H 3BO 3(or B 3O 3)and 3N pure CaCO 3 were mixed and preheated at 1100℃,then encapsulated in a Pt crucible with a single crystal seed.Thickness of the crucible we chose was within the range of 0.1—0.6mm.After thorough melting of the raw materials and partial melting of the seed(obtained by spontaneous nucleation),the crucible descended at a rate of <0.8mm/h.The vertical temperature gradient at the growth interface in the BR furnace was about 30—40℃/cm,and the temperature profile was kept symmetrical.Typical size of the GdCOB crystal without macroscopic defects obtained in this way was 25mm in diameter and 60mm in length.Due to the small temperature gradient in growth and the cooling process similar to the anneal after growth,cracking problem which was often met in pulling techniques was overcome efficiently.展开更多
文摘Inorganic nonlinear optical crystal GdGa 4O(BO 3) 3(GdCOB) possesses moderate NLO efficient (1.3pm/V) ,high damage threshold(>1GW/cm 2),and wide transmission wave band(320-2700nm).In addition,it is chemically stable,nonhygroscopic and easy to process,which makes GdCOB a promising practical NLO material for frequency conversion.Crack free single crystals of GdCOB with large size have been grown using the vertical Bridgman method for the first time.Stoichiometric amounts of starting materials 4N pure Gd 3O 3,H 3BO 3(or B 3O 3)and 3N pure CaCO 3 were mixed and preheated at 1100℃,then encapsulated in a Pt crucible with a single crystal seed.Thickness of the crucible we chose was within the range of 0.1—0.6mm.After thorough melting of the raw materials and partial melting of the seed(obtained by spontaneous nucleation),the crucible descended at a rate of <0.8mm/h.The vertical temperature gradient at the growth interface in the BR furnace was about 30—40℃/cm,and the temperature profile was kept symmetrical.Typical size of the GdCOB crystal without macroscopic defects obtained in this way was 25mm in diameter and 60mm in length.Due to the small temperature gradient in growth and the cooling process similar to the anneal after growth,cracking problem which was often met in pulling techniques was overcome efficiently.
