Crystals for Stimulated Raman Scattering
EKSMA OPTICS offers crystalline materials - Barium Nitrate - Ba(NO3)2 and undoped potassium gadolinium tungstate KGd(WO4)2 or KGW which have attracted much interest as most suitable crystals for stimulated Raman scattering (SRS). These materials can be used for frequency conversion in lasers for extending of tuning range. SRS in crystals is compatible with current all-solid-state technology and provides a very simple, compact means of frequency conversion.
Ba(NO3)2 has a highest Raman gain coefficient. The gain coefficient affects the threshold for Raman laser. However the thermal lensing is particularly strong in this material. This is indicated by the large value dn/dT and low thermal conductivity. Thermal effects are significantly smaller in KGW. This along with the high damage threshold make the crystal an excellent candidate for power scaling.
Comparing Ba(NO3)2 and KGW for Raman application Ba(NO3)2 are more effective in case of ns pulses and KGW – in case of ps pulses.
| Crystal symmetry | monoclinic, C2/c |
| Transmission range | 0.35-5.5 µm |
| Density | 7.27 g/cm3 |
| Hardness Mohs | 4-5 |
| Refractive indices @ 1064 nm | ng = 2.061; np = 1.982; nm = 2.010 |
| Raman shift |
901 cm-1 (p[mm]p) |
| Raman gain, pump 1064 nm |
3.3 cm/GW (901 cm-1) |
| Thermal conductivity, W/mK | Ka = 2.6; Kb = 3.8; Kc = 3.4 |
| dn/dT | 0.4 x 10-6 K-1 |
| Optical Damage threshold | > 10 GW/cm2 |
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