Growth of large Ti:Sapphire crystals by horizontal directional solidification in argon atmosphere

Growth of Large Ti:Sapphire Crystals by the Method of HDC with Gradient Doping

“…The main contribution to the absorption spectra of Ti:Sa belongs to the content of anion and cation vacancies, titanium ions in the charge states 3+ and 4+, and impurities and to complex defects on their base. For obtaining Ti:Sa laser crystals, it is necessary to create the reducing conditions that provide the maximum transition of the ions Ti 4+ → Ti 3+ and prevent formation of the centers (Ti 3+ –Ti 4+ ) of parasitic absorption. , …”

“…Ti:Sa crystals were grown in a thin-walled molybdenum crucible (“boat”) in a CO+H 2 and argon atmosphere. Under such conditions, gaseous reducing components are formed spontaneously due to the interaction of residual gases and vapors of the melt with the carbon–graphite constructional materials of the furnace. , …”

“…Between 1990 and 2010, a new effective technology for growing in protective reducing media based on CO and H 2 using carbon-containing constructional materials was developed, which significantly reduced the burnout of the thermal zone. , At present, leucosapphire crystals of record size up to ∼500 × 1000 × 50 mm 3 are obtained by the modified HDC method. , This technology is successfully used to grow Ti:Sa laser crystals too. Due to the reducing conditions of growth, an efficient transition of Ti 4+ → Ti 3+ ions occurs. − As a result, crystals with a concentration of up to 0.3–0.35 mass % Ti were obtained.…”

Growth and characterization of large-scale Ti:sapphire crystal using heat exchange method for ultra-fast ultra-high-power lasers

“…Methods for obtaining large-scale Ti:sapphire crystals reported in the past 10 years include the heat exchanger method 11 (HEM), Kyropoulos 12 (KY) method, temperature gradient technology 13 (TGT) and horizontal directional solidification 14 (HDS). Among these methods, HEM is the most promising technique for growing large-scale Ti:sapphire crystals.…”

Optical property measurements of 235 mm large-scale Ti:sapphire crystal

“…Large-scale Ti:sapphire crystals are required to meet the requirements for higher-power laser systems. The Kyropoulos method (KY) [8] , the heat exchange method [9] (HEM), the temperature gradient method [10] (TGT), and horizontal directional solidification [11] (HDS) are the principal methods used to grow large-scale Ti:sapphire crystals. The HEM is the preferred method for its numerous advantages over other methods [12] including independently controlling the temperature gradient of the melt and the crystal, a stable growth interface, reducing conditions that inhibit the formation of Ti 4þ ions, and post growth in situ isothermal annealing.…”