Laser media: Double halogenides / laser crystals
New laser crystals of double halogenides
MPb2X5
MPb2X5 ( M=K, Rb X= Cl, Br): RE
R&D possibilities
Crystals of group MPb2X5 ( M=K, Rb X= Cl, Br): RE is a new promising active media for lasers, operating on different wavelengths in the range from UV to mid-IR, including those for TV amplifiers with diode pumping. Interest to this material, which has high RE segregation coefficients and a set of attractive properties increased considerably to date.
Main characteristics of MPb2X5
| KPb2Cl5 | RbPb2Cl5 | KPb2Br5 | RbPb2Br5 | ||
| Transparency range, µm | 0.3 – 20 | 0.3 - 20 | 0.3 - 30 | 0.3 - 30 | |
| Space group | P22/c | P22/c | P22/c | l4mcm | |
| Melting temperature, °C | 434 | 423 | 382 | 382 | |
| Density, G/cm3 | 4.629 | 5.041 | 5.619 | 5.83 | |
| Reflection Index (632.8 nm) | 2.019 | 2.019 | 2.2 | 2.2 | |
| Thermal conductivity, W/m*K | 4 | 4 | - | - | |
| Mohs hardness | 2,5 | 2,5 | 2,5 | 2,5 | |
| Phonon energy, cm-1 | 203 | 203 | 133 | 133 | |
| Lattice parameters | |||||
| a, Å | 8.854(2) | 8.959 | 9.256(2) | 8.41 | |
| b, Å | 7.927(2) | 7.973 | 8.365(2) | 8.365(2) | |
| c, Å | 12.485(3) | 12.493 | 13.025(3) | 14.5 | |
| (deg) | 90.05(3) | 90.12 | 90.00(3) | 90.00(3) | |
| V | 876.3(4) | 895.3 | 1008.4(4 | 1025.6 | |
| Z | 4 | 4 | 4 | 4 | |
| Chemical stability | Chemical stability | ||||
Low energy of phonons in halogenides provides mainly radiative transitions between adjacent levels with the gap Δ Е ≥ 1500 cm-: as a result emission bands cover the wide spectral region from UV (transitions from upper excited levels) to 9-10 µm in the mid-IR (transitions within both excited and ground RE multiplets);
Complex of long decay times for lower states, high values of absorption cross-sections and low rates of the nonradiative multiphonon relaxation makes these crystals promising for their application as active media for UV/VIS lasers with up-conversion pumping;
It is important that intense absorption bands match the laser diodes emission for many RE ions in MPb2X5 crystals.
| Rare – earth ion | Pr | Nd | Dy [19] | Er | Yb [19] | Ym | Ho | |
| Maximum peak Absorption cross section, δρ (λ max), 10-20 cm2 |
10.9 | 14.9 | 51.8 | 21.5 | 1.78 | 2.85 | 11.0 | |
| Wavelength (λ max), nm | 487 | 589 | 129.7 | 379.4 | 982 | 797.9 | 453 | |
| Peak absorption cross section for LD pumping δρ (λ max), 10-20 cm2 |
- | 6.22 | 0.9 | 4.8 | 1.78 | - | - | |
| Wavelength (λ), nm | - | 808.2 | 810.4 | 982.6 | 982 | 800 | 900 | |
Using the MPb2X5 ( M=K, Rb X= Cl, Br) : RE one can create lasers with diode laser pumping, where different mechanisms of energy transformation, including those with simultaneous and cascade generation, with minimum Stoke's losses, are realized;
Relatively broad, structureless luminescence bands in MPb2X5 ( M=K, Rb X= Cl, Br): RE crystals allow fine tuning of the stimulated emission frequency;
To date stimulated emission has been obtained for 1.064 µm (Nd), 2.4 µm (Dy) and 4.3 µm (Er)
We suggest the MPb2X5 ( M=K, Rb X= Cl, Br) : RE crystals for joint investigation of the stimulated emission using different schemes;
Variation of RE type and dopant concentration are possible for Variation of RE type and dopant concentration are possible for MPb2X5 (M=K, Rb; X=Cl, Br):RE crystals
Typical sizes of optical elements are 4x4x5 (15) mm3;
Protective/antireflection coatings may be performed on the aperture surfaces of the produced elements.
Application
- Active media for lasers, laser amplifiers.
- We are opened for a joint research proposals in crystal growth, as well as an investigations of a new materials
We are able to provide suitable Anti-reflection / Protective, etc. coatings tailored to customer’s specifications, reflectivity curves are applied upon request.