Laser media: Double halogenides / laser crystals

New laser crystals of double halogenides


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.


  • 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.