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Alexandrite Cr3+:BeAl2O4

Alexandrite(Cr3+:BeAl2O4) is an excellent broadband tunable laser crystal with a wavelength tuning range of 701-858 nm.The crystal has the advantages of high hardness, high thermal conductivity, high damage threshold, low threshold and high efficiency, it has excellent thermal shock resistance, which is 5 times higher than that of Nd:YAG.

Alexandrite(Cr3+:BeAl2O4) is widely used in dermatology, laser precision processing, remote sensing, atmospheric radar, and medical laser equipment, primarily for long pulses, Q-switching, and picosecond 755 nanometer lasers.

Properties of Alexandrite Cr3+:BeAl2O4

Chemical Formula:

Yb:Y₃Al₅O₁₂

Crystal Structure:

Orthorhombic, space group Pnma

Lattice Constants:

a=5.476Å b=9.404, c=4.427

Melting Point:

1870°C

Density:

3.69 g/cm³

Mohs Hardness:

8.5

Thermal Conductivity:

23 W/m /K

Thermal Diffusion Coefficient:

5.9 //a, 6.1 //b, 6.7 //c

Thermal Shock Resistance:

35-74 W/cm

Refractive Index:

n_a=1.736, n_b=1.741, n_c=1.734 @750 nm

Lasing Wavelength:

701-858 nm

Emission Band:

701-900 nm

Stimulated Emission Cross Section:

0.7 x 10^-20 < cm²

Absorption Bands:

400-700 nm

Intrinsic Flouresence Lifetime:

262 μs

Sellmeier equation( λ in μm):

Advantages:

Alexandrite is bi-axis anisotropic, the absorption and gain properties are strongly dependent on the polarization direction of pump light. The crystal has a wide absorption bandwidth and can cover most of the visible light region. Blue, green, yellow, and red light lasers can all be used as pump sources for Alexandrite laser. Different bands of the pump source have different advantages:

1.When blue light is used as the pump source, Alexandrite laser can achieve a broader emission spectrum, which is suitable for ultra-precision material processing that requires a broad- spectrum laser.

2.When yellow or red light is used as the pump source, the laser has high quantum efficiency and is expected to achieve high average power.

3.The 532 nn green laser beam generated by Nd:YVO4 doubling has good quality and high output power, and is usually the preferred pump source for Kerr lens mode-locked lasers.

Absorption spectra of Alexandrite

General Specifications of Alexandrite Laser Crystal

1) Orientation:

+/-0.5°

2) Wavefront Distortion:

λ/8 per inch

3) Surface quality:

better than 10/5 Scratch/Dig

4) Parallelism:

30 arc seconds

5) Perpendicularity:

5 arc minutes

6) Surface flatness:

< λ/10 at 633 nm

7) Clear aperture:

Central 95%

8) Chamfer:

0.15mm @45°

9) Standard sizes:

Dia. 5x115, 7x110, 7x120, 6.35x120, 8x120, 9.53x117mm; Slab is also availabe;

10) Coating:

AR/AR755nm, HR755nm, PR 755nm

11) Waranty:

one year.