Co Spinel Q Switch Crystals

Product Detail

Description

Passive Q-switches or saturable absorbers generate high power laser pulses without the use of electro-optic Q-switches, thereby reducing the package size and eliminating a high voltage power supply. Co²⁺:MgAl₂O₄ is a relatively new material for passive Q-switching in lasers emitting from 1.2 to 1.6µm, in particular, for eye-safe 1.54µm Er:glass laser, but also works at 1.44µm and 1.34µm laser wavelengths. Spinel is a hard, stable crystal that polishes well. Cobalt substitutes readily for magnesium in the Spinel host without the need for additional charge compensation ions. High absorption cross section (3.5×10^-19 cm²) permits Q-switching of Er:glass laser without intracavity focusing both with flash-lamp and diode laser pumping. Negligible excited-state absorption results in high contrast ratio of Q-switch, i.e. the ratio of initial (small signal) to saturated absorption is higher than 10.






Absorption Spectrum of Co:Spinel crystal



Absorption Spectrum of Co:Spinel crystal



Transmission Spectrum of Co:Spinel crystal




Features

•  Suitable for 1540 nm eye-safe lasers

•  High absorption section

•  Negligible excited state absorption

•  High optical quality

•  Uniformly distributed Co

                                                     

Applications

•  Eye-safe 1540 nm Er:glass laser

•  1440 nm laser

•  1340 nm laser

•  Eye-safe laser range finder




Parameters

Property	Value
Chemical formula	Co2+:MgAl2O4
Crystal structure	Cubic
Lattice parameters	8.07Å
Density	3.62 g/cm3
Melting Point	2105°C
Refractive Index	n=1.6948 @1.54 µm
Thermal Conductivity /(W·cm-1·K-1@25°C)	0.033W
Specific Heat/ (J·g-1·K-1)	1.046
Thermal Expansion /(10-6 /°C@25°C )	5.9
Hardness (Mohs)	8.2
Extinction Ratio	25dB
Orientation	[100] or [111] < ±0.5°
Optical density	0.1-0.9
Damage Threshold	>500 MW/cm2
Doping concentration of Co2+	0.01-0.3 atm%




Specifications


Property	Value
Concentrations	(0.05~0.35) wt%
Absorption coefficient	0 ~ 7 cm-1
Ground-state absorption cross-section sGSA(E-19 cm2)	2.8(±0.4)@1340nm
Excited state absorption cross-section sESA (E-20 cm2)	2.0(±0.6)@1340nm
Ground-state absorption cross-section sGSA(E-20 cm2)	3.5(±0.4)@1540nm
Excited state absorption cross-section sESA (E-20 cm2)	1.0(±0.6)@1540nm
Working wavelength	1200 – 1600 nm
End Configuration	Flat/Flat
Figure of Merit(FOM)	100~300
Coatings	AR/AR@1540,R<0.2%; AR/AR@1340,R<0.2%




Polishing Specification

Property	Value
Orientation Tolerence	< 0.5°
Thickness/Diameter Tolerance	±0.05 mm
Surface Flatness	<?/8@632 nm
Wavefront Distortion	<?/4@632 nm
Surface Quality	10/5
Parallel	10?
Perpendicular	5´
Clear Aperture	>90%
Chamfer	<0.1×45°
Maximum dimensions	Dia(3-15)×(3-50)mm




Standard products


Initial transmission @1064nm	Dimensions,mm	Coatings	Surface Flatness	Surface Quality (scratch/dig)
T0=30%	dia 5	AR=0.2% @1340nm Or AR=0.2% @1540nm	<?/8@632 nm	10/5
	3x3
	5x5
T0=40%	dia 5
	3x3
	5x5
T0=50%	dia 5
	3x3
	5x5
T0=60%	dia 5
	3x3
	5x5
T0=70%	dia 5
	3x3
	5x5
T0=80%	dia 5
	3x3
	5x5
T0=85%	dia 5
	3x3
	5x5
T0=90%	dia 5
	3x3
	5x5
T0=95%	dia 5
	3x3
	5x5
T0=97%	dia 5
	3x3
	5x5