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.
|Refractive Index||n=1.6948 @1.54 μm|
|Thermal Expansion /（10-6 /°[email protected]°C ）||1.046|
|Specific Heat/ (J·g-1·K-1)||5.9|
|Orientation|| or  < ±0.5°|
|Damage Threshold||>500 MW/cm2|
|Doping concentration of Co2+||0.01-0.3 atm%|
|Absorption coefficient||0 ～ 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 wavelength||1200 – 1600 nm|
|Figure of Merit(FOM)||100~300|