Del Mar Photonics - Newsletter

Undoped monoclinic KGd(WO4)2 (KGdW)

We can grow crystals with aperture up to 50x50mm2 and 50-70mm length.
Request a price for the KGW element 5x5x50mm, b-cut, AR/AR-coated @1064+1180nm



Crystal structure

Monoclinic centrosymmetric (C62h-2/m)

Site symmetry / Coordination number / Gd3+ ionic radius

C2 / 8 / 0.938 Å

Temperature of the polymorphic transformation / melting

1005°C / 1075°C

Crystallographic setting

C2/c or I2/c (a1 = a+c, b1 = b, c1 = –c)

Unit-cell parameters

a=10.652(4)Å, b=10.374(6)Å, c=7.582(2)Å,
β=a^c=130.8(0)° (C2/c);

a1=8.085(1)Å, b1=b, c1=c, β1=a1^c1=94.3(9)° (I2/c)


7.11 g/cm3

Specific heat

363 J/kg×K

Optical indicatrix frame

biaxial; Np=b, c^Ng=19.3°, a^Nm=60.1° (C2/c);

Np=b1, c1^Ng=19.3°, a1^Nm=14.9° (I2/c)

Refractive indices

np=2.0109, nm=2.0414, ng=2.0950 at 633 nm;

np=1.9818, nm=2.0101, ng=2.0609 at 1064 nm

Optical axes position

Ng±42.6° (Np-Ng plane) at 633 nm

Thermal conductivity

2.5 (Np), 3.0 (Nm), 3.5 (Ng) [W/mK]

Linear thermal expansion

α'11=7.6, α'22=1.7, α'33=20.6, αvol=29.9 [10-6 K-1];

αm=11.3, αg=16.9 [10-6 K-1]

Principal frame of the thermal expansion tensor

X'2=b(Np), X'3^Ng = X'1^Nm=32.1°

Thermo-optic coefficients

dnp/dT=-14.4, dnm/dT=-9.7, dng/dT=-15.7 [10-6 K-1] at 633 nm;

dnp/dT=-15.7, dnm/dT=-11.8, dng/dT=-17.3 [10-6 K-1] at 1064 nm

Strongest phonon modes

901 cm-1 (E || Nm), 768 cm-1 (E || Ng)

Nonlinear refractive index

n2~25×10-16 cm2/W (E || Nm), ~15×10-16 cm2/W (E || Np)

Raman shift

901 cm-1 (p[mm]p), 768 cm-1 (p[gg]p)

Raman gain, @1064 nm

3.3 cm/GW (901 cm-1), 4.4 cm/GW (768 cm-1)



Specifications for the KGW Raman elements

Material :                                 KGd(WO4)2
Dimension tolerances:             ±0,05 mm
Surface quality:                       10/5 S/D
Surface flatness:                      l/10 @632.8nm
Perpendicularity:                     ±5 arcmin
Parallelism:                              ±5 arcsec
Chamfers:                                <0.1 mm @ 45°
Orientation:                             b-cut or Ng-cut


Solid-state Raman Shifter

The Solid State Raman Shifter LZ series uses innovative technology Ba(NO3)2 (shift 1047 cm-1) and KGdWO4 (shift 767.3 and 901.5 cm-1) crystals. The crystals’ unique properties allow their application for Raman frequency conversion ranging from VIS to IR. The nonlinear crystal placed in the optimized cavity ensures high conversion efficiency of the the pump radiation to the 1st, 2nd or 3rd order Stokes, alongside with low generation thresholds. Upon your order mirrors can be installed into the LZ221 Shifter for obtaining definite Stokes, as well as for receiving the multi-line output (generating several components simultaneously) with the total conversion efficiency more than 50%. The design of this device minimizes the needs for user adjustments and allows to easily replace cavity mirrors while re-aligning the Raman Shifter from one wavelength to another.
KGW Raman crystals


We are looking forward to hear from you and help you with your optical and crystal components requirements. Need time to think about it? Drop us a line and we'll send you beautiful Del Mar Photonics mug (or two) so you can have a tea party with your colleagues and discuss your potential needs.


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