Yb: CaF2 is a new laser crystal which is formed by doping Yb into CaF2. The main emission peak are reported to be at 1033 nm and 1050 nm with the emission linewidth of 70 nm. Because of the absence of undesired loss transitions such as up-conversion, excited state-absorption and concentration quenching, their low quantum defect, a comparably long fluorescence lifetime, high thermal conductivity and wide emission linewidth, ytterbium-doped CaF2 is preferably utilized for high-power diode-pumped systems and laser amplifiers with high optical-to-optical conversion efficiencies, diode-pumped femtosecond (fs) lasers and amplifiers are one of the important potential application. Furthermore, at the current point of view the crystal growth technologies of Yb: CaF2 promise to be scalable, which allows for the production of excellent optical quality material.
Physical and Chemical Properties
| Crystal Structure | cubic |
| Lattice Constants | 5.462 Å |
| Density | 3.18 g/cm3 |
| Melting Point | 1418°C |
| Thermal Conductivity /(W·m-1·K-1@25°C) | 9.71 |
| Specific Heat/ (J·g-1·K-1) | 0.8876 |
| Thermal Optical Coefficient(dn/dT) | −11.3 |
| Thermal Expansion /（10-6·K-1@25°C ） | 19 |
| Hardness (Mohs) | 4 |
| Young`s Modulus /GPa | 146 |
| Tensile Strength/Gpa | 2 |
Optical and Spectral Properties
| Laser Transition | 2F5/2→2F7/2 |
| Laser Wavelength | 1033/1050 |
| Optical Density | 0.1-0.8 |
| Absorption Coefficient | 1.0 cm-1 ~ 7 cm-1 |
| Pump Wavelength | 980 nm |
| Emission State Absorption Cross Section | 2.2×10-20 cm2 |
| Ground State Absorption Cross Section | 0.8×10-20 cm2 |
| Fluorescence Lifetime | 2.4 ms |
| Emission Band Width | 70 nm |
| Refractive Index @1.064μm | 1.2996 |
| Thermal Optical Coefficient (10−6 K−1) | -3.7 |
| Transmission | 10% to 90% |
| Damage Threshold | > 500 MW/cm2 |
Absorption and Emission Spectrum
Material and Specifications
| Concentration Tolerance (atm%) | 0.5 mol % ~ 30 mol % |
| Orientation | [111] or [100] < ±0.5° |
| Orientation Tolerance | < 0.5° |
| Parallelism | 10〞 |
| Perpendicularity | 15ˊ |
| Surface Quality | 10-5(MIL-O-13830A) |
| Wavefront Distortion | <λ/8 @632 nm |
| Surface Flatness | <λ/8 @632 nm |
| Clear Aperture | >90% |
| Chamfer | <0.1×45° |
| Thickness/Diameter Tolerance | ±0.05 mm |
| Maximum Dimensions | 2*2-15*15 mm×20mm |
| Thermal Shock Resistance Parameter | 800 W/m |
| Coatings | AR≤ 0.2% @1030nm |
Standard Products
| Material | Dimensions，mm | Coatings |
| Yb(5%):CaF2 | dia 5 | AR≤ 0.2% @1030+940nm |
| 3×3 | ||
| 6×6 | ||
| Yb(3%):CaF2 | dia 5 | |
| 3×3 | ||
| 6×6 |
Wide emission linewidth
Low quantum defect
Comparably long fluorescence lifetime
High thermal conductivity
Thermo-optical coefficient
Kerr-lens mode-locked oscillator
Yb: CaF2 thin-disk laser
Diode-pumped Yb: CaF2 amplifier