LCS, Inc. represents
Laser Crystal Solutions project
Stage I: Industrial Crystal Growth: Laser host material KGW and KYW

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Nonlinear Crystal products:

LBO nonlinear crystals
Lithium Triborate
Chemical formula: LiB3O5
BBO nonlinear crystals
beta-Barium Borate
Chemical formula: BaB2O4
BBO e-o switches
KTP nonlinear crystals
Potassium Tytanil Phosphate
Chemical formula: KTiOPO4
KGW, KYW laser host material
Raman Shifters (KGW, KYW)
Optical Coatings
anti-reflection and protective

Laser products:

Optical Parametric Oscillator

Contact information:

Zelenaja gorka str. 1,
630060, Novosibirsk,
Russian Federation
Phone/Fax: +7 (383) 334 80 81

e-mail: sales@lc-solutions.com

Nd doped Potassium Gadolinium Tungstate KGd[WO4]2 (Nd:KGW)

Standard Specifications
Available Optical Coatings

- high doping levels of Nd3+ ions upto 10 at. % (6.4 x 1020 cm-3) in KGW. The high level of doping allows to build a compact, high gain diode-pumped microlaser;
- Nd:KGW absorption and emission are polarized due to the crystallographic structure. It has larger absorption and emissions cross-sections, where its absorption bandwidth (FWHM) is larger (about 10 nm) than Nd:YAG (1,5 nm), therefore the temperature control and wavelength stability of the pumping diode are less critical. Moreover, the larger bandwidth (FWHM) of the Nd:KGW emission (720 GHz) relative to YAG (120 GHz) can be used to generate ultrashort pulses.
- thermal lensing in KGW is smaller than YAG, due the small change of refraction index with the temperature Dn/DT, which results in better beam quality in tungstates compared to other hosts.
- the strict advantage of Nd:KGW crystal is the possibility to generate stimulated self-Raman scattering conversion at about 1540 nm. From the 1351 nm laser emission, the eye-safe range near 1540 nm can be reached.
- because of Nd:KGW short absorption length, the beam quality of very short resonators is better than that of a similar Nd:YAG laser.
- despite its short storage time Nd:KGW performs very good in actively and passively Q-switched operation, leading to high peak powers that are favourable for efficient upconversion.

Comparison with some other crystals

Parameter

Nd:YAG

Nd:YVO4

Nd:KGW

Nd:YAP

Nd3+ concentration,
[1020 cm-3]

1.38 (1 at. %)
1.725 (1.25 at. %)

1.37 (1.1 at. %)

1.92 (3 at. %)
2.62 (4.1 at. %)
6.4 (10 at. %)

3.546 (1.8 at. %)

lemission, [nm]

1064.15

1064.30

1067.20

1079.50

sem, [1019 cm2]

3.5 (at 1.06 mkm)
0.9 (at 1.3 mkm)

15.6 (at 1.06 mkm)

3.4 (at 1.06 mkm)
0.76 (at 1.3 mkm)

2.4 (at 1.07 mkm)

sabs, [1019 cm2]

2.3 (at 810 nm)

2.6 (at 810.6 nm)

Fluorescense lifetime, [mks]

240 (0.7 at. %)
220 (1.1 at. %)

99 (1.1 at. %)

120 (3 at. %)
99 (4.5 at. %)

180 (0.77 at. %)

Refractive index at 1.06 mkm

1.82

no = 1.9573
ne = 2.1652

2

1.93

Density

4.54

4.22

7.27

5.4

Thermal conductivity, [W/mK]

13

C// = 5.23
C_|_ = 5.1

2.8 (100)
2.2 (010)
3.5 (001)

11

Thermal expansion coefficient, [10-6K-1]:
(100)
(010)
(001)



8.2
7.7
7.8



4.43
4.43
11.37



4.0
3.6
8.5



9.5
4.2
10.8

Dn/DT, [10-6K-1]

7.3

8.5

0.4

9.7

Hardness (Mohs)

8.5

5

4.5

8.5

Possible dopant concentrations

Nd:KGW

1 - 8 at. %

Applications

Lasers based on Nd:KGW crystals could operates both in a flashlamp-pumped mode, Ti:Sapphire pumping configuration and diode-pumping configuration.
Some of the optical characteristics of Nd:KGW makes it attractive for compact or micro-laser systems, having low-to-medium average-output power and high repetition rates. This stems from its high concentration doping level, polarized laser output, and its lower thermal lensing relative to other hosts.
Nd:KGW is well suited for end-pumping with high peak power laser diode arrays.
Nd:KGW emission cross-section at 1351 nm is used for medical applications.
For the Raman laser applications, the eye-safe emission range (1540 nm) is reachable when the Nd:KGW crystal is used as both laser media and Raman shifter.
Development of new solid state lasers requires crystals with low excitation threshold and suited to be excited by the emission of diode lasers. Monoclinic KGW crystal is a good laser host, providing high efficiency for stimulated emission at low pumping energies, both with lamp or laser diode excitation. KGW crystals are used as a laser host for Nd3+ ions because of the high efficiency of the 4F3/2 --> 4I11/2 transition. Recently, some researches focuse attention on crystals with relevant cubic nonlinearity hi(3) because of the possibility to obtain lasers with Stimulated-Raman scattering (SRS) self-frequency conversion. The KGW possesses an effective cubic nonlinearity of about 10-13 esu and the Nd:KGW system presents a good efficiency in the process of SRS self conversion

Please, contact us for any specific requirements.

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