What are the raw materials for laser crystals?

　　The raw materials of laser crystals mainly include host crystals and activator ions, which are numerous. The selection of host crystals and activator ions varies depending on different application needs and wavelength ranges.

　　Host Crystals

　　Host crystals are the base materials of laser crystals. Common host crystals include:

　　Oxides: such as yttrium aluminum garnet (YAG, Y3Al5O12), aluminum oxide (Al2O3), strontium titanate (SrTiO3), calcium titanate (CaTiO3), etc.

　　Fluorides: such as calcium fluoride (CaF2), lithium fluoride (LiF), sodium fluoride (NaF), etc.

　　Phosphates: such as yttrium phosphate (YPO4), neodymium phosphate (NdPO4), etc.

　　Borates: such as beryllium borate (Be2B2O7).

　　Other types: such as sapphire (Al2O3), ruby (Al2O3:Cr3+), fluorite (CaF2), etc.

　　Activator Ions

　　Activator ions are active components doped into host crystals to achieve laser emission. Common activator ions include:

　　Rare earth ions: such as neodymium (Nd3+), yttrium (Y3+), ytterbium (Yb3+), erbium (Er3+), thulium (Tm3+), holmium (Ho3+), etc.

　　Transition metal ions: such as chromium (Cr3+), copper (Cu2+), manganese (Mn2+), etc.

　　Other ions: such as vanadium (V3+), lanthanum (La3+), etc.

　　Specific Laser Crystal Examples

　　Depending on the application scenario, specific examples of laser crystals include:

　　Nd:YAG (Neodymium-doped yttrium aluminum garnet): Used in medium and high-power lasers.

　　Nd:YVO4 (Neodymium-doped yttrium vanadate): Used in low-power lasers.

　　Ti:Al2O3 (Titanium-doped sapphire): Used in tunable and ultrafast lasers.

　　Er:YAG (Erbium-doped yttrium aluminum garnet): Used in medical and industrial lasers.

　　Ho:YAG (Holmium-doped yttrium aluminum garnet): Used in medical laser surgery.

　　Special Function Laser Crystals

　　Some laser crystals have special functions, such as:

　　Nonlinear optical crystals: such as BBO, LBO, etc., used for frequency conversion.

　　Broadband laser crystals: such as chromium-doped ruby (Cr:Al2O3), used for broadband laser emission.

　　Preparation Process and Property Requirements

　　The preparation of laser crystals needs to meet the following conditions:

　　Physicochemical stability: The host crystal must have good thermal and chemical stability.

　　Optical homogeneity: The crystal must have high optical homogeneity to reduce losses during laser transmission.

　　Activator ion compatibility: The activator ions must be compatible with the host crystal to achieve efficient laser emission.