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Yb:KGW Laser Crystal

Yb:KGW-Ytterbium doped Potassium-Gadolinium Tungstate crystals - (Yb:KGd(WO4)2 or Yb:KGW) is an excellent laser gain material which has important advantages over the widely used Nd3+ doped materials. Yb:YAG's broad spectral emission band 1023-1060nm allows the generation of short (ps or fs) laser pulses. Its wide absorption spectrum at 980 nm and high absorption of pump radiation allow an efficient use of diode laser pumping. Compared with YAG used as hosts for Yb3+, KGW has the advantage of larger absorption cross section, which decreases the minimum pump intensity necessary to achieve transparency in the quasi-two-level system of ytterbium.

Properties of Yb:KGW

Chemical Formula:

Yb:KGd(WO4)2

Crystal Structure:

monoclinic; Point group: C2/c

Lattice Constants:

a = 8.09; b = 10.43; c = 7.588Å; β=94.4°

Melting Point:

1075°C

Density:

7.27 g/cm³

Mohs Hardness:

Thermal Expansion Coefficient:

a[100] = 4 x 10E-6; a[010]= 1.6 x 10E-6; a[001]= 8.5 x 10E-6 /K

Thermal Conductivity:

K[100] = 0.026; K[010]= 0.038; K[001] = 0.034 W/cm/K

Yb:YAG Optical Properties

Refractive Index:

n_q = 2.033; n_p = 2.037; n_m = 1.986

Lasing Wavelength:

1023-1060 nm

Absorption Bands:

981 nm(FWHM 3.7nm)

Flouresence Lifetime:

600 µs (5% doping)

Capability of Yb:KGW Laser Crystal

1) Yb dopant concentration:

5%, 10% atm%

2) Max Diameter:

20 mm

3) Length:

50 mm

4) Anti-reflection Coating:

R < 0.1% @ 1030 nm

High transmission Coating:

T > 95% @ 940 nm

High reflection Coating:

R > 99.8% @ 1030 nm

General Specifications of Yb:KGW Laser Crystal

1) Orientation:

<010> crystalline direction (+/-0.5°)

2) Max sizs:

20x20x50mm

3) Surface quality:

better than10/5 Scratch/Dig

4) Parallelism:

10 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) Damage threshold:

over 15J/cm² (without coating)

10) Yb dopant concentration: