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Co Spinel Passive Q-Switch Crystal Laser Crylink

Co: Spinel

Co:Spinel (Cobalt-doped magnesium aluminate spinel; Co:MgAl2O4) allows the generation of a short nanosecond pulse with high peak power around the eye-safe wavelength of 1.5um, perfect for telemetry applications. The absorption spectrum of Co2+-doped MgAl2O4 exhibited a broad absorption band in the wavelength range of 1200–1600 nm, which indicated that Co2+ ions substituted for the tetrahedrally coordinated Mg2+ ions in the MgAl2O4 lattice. Passive Q-switching of solid-state lasers with solid-state saturable absorbers is a beautiful Q-switching technique. It allows the development of compact and low-cost laser sources of nano and sub-nanosecond pulses for various applications.

Co:Spinel——saturable absorbers for the passive Q-switching of solid-state lasers operating at an eye-safe wavelength of 1.5 μm

Lasers emitting at 1.5µm are of great interest for several industrial applications. This interest is, first of all, due to the eye safety of 1.5-µm radiation. Other advantages of this wavelength are high transparency in the atmosphere and fused silica waveguides and the availability of sensitive room-temperature light detectors(Ge and InGaAs photodiodes). All this makes 1.5µm lasers very attractive for applications in range-finder, environmental sensing, telecommunications, surgery, etc. Co:Spinel absorption peak is close to 1520nm, primarily used in eye-safe lasers. The absorption cross-section at 1520nm is 3.5×10-19cm2 and at 1331 is 2.8×10-19cm2. It has been reported as a Q-switch crystal for Er,Yb Glass, Nd:GYSGG,Nd:YALO3.


Chemical formulaCo2+:MgAl2O4
Crystal structureCubic
Lattice parameters8.07Å
Density3.62 g/cm3
Melting Point2105°C
Refractive Indexn=1.6948 @1.54 μm
Thermal Conductivity/(W·cm-1·K-1@25°C)0.033W
Thermal Expansion /(10-6 /°C@25°C )1.046
Specific Heat/ (J·g-1·K-1)5.9
Hardness (Mohs)8.2
Extinction Ratio25dB
Orientation[100] or [111] < ±0.5°
Optical density0.1-0.9
Damage Threshold>500 MW/cm2
Doping concentration of Co2+0.01-0.3 atm%
Concentrations(0.05~0.35) wt%
Absorption coefficient0 ~ 7 cm-1
Ground-state absorption cross-section GSA(E-19 cm2)2.8(±0.4)@1340nm
Excited state absorption cross-section ESA(E-20 cm2)2.0(±0.6)@1340nm
Ground-state absorption cross-section GSA(E-20 cm2)3.5(±0.4)@1540nm
Excited state absorption cross-section ESA(E-20 cm2)1.0(±0.6)@1540nm
Working wavelength1200 – 1600 nm
End ConfigurationFlat/Flat
Figure of Merit(FOM)100~300

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