Passive Q-switch

/Co2+:MgAl2O4 Cobalt-doped magnesium aluminate spinel

Co2+:MgAl2O4 Cobalt-doped magnesium aluminate spinel

Co2+:MgAl2O4 Cospinel is a relatively new material for passive Q-switching in lasers emitting from 1.2 to 1.6 μm, in particular, for eye-safe 1.54 μm Er:glass laser, but also works at 1.44 μm and 1.34 μm 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 of Q-switch, i.e. the ratio of initial (small signal) to saturated absorption is higher than 10.

  • Product Origin:

  • Shipping Port:

    Fuzhou, China
  • Lead Time:

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  • Product Detail


Co2+:MgAl2O4 Cobalt-doped magnesium aluminate spinel is a relatively new material for passive Q-switching specially for eye-safe 1.54 μm Er:glass laser, but also works at 1.44 μm and 1.34 μm wavelengths.

Main applications:

1) Passive Q-switch for Radar and Ranging Er:Glass lasers @1,35µm

2) Passive Q-switch for Medical lasers @1,500 µm


1) Rare excited absorption

2) High constant of Q-switch

3) High absorption section

4) Long excited lifetime

5) Evenly distributed cobalt

6) Wide absorption band

Basic properties of Cospinel

Chemical formula


Crystal structure


Lattice parameters



3.62 g/cm3

Melting Point


Refractive Index

n=1.6948 @1.54 μm

Thermal Conductivity/(W·cm-1·K-1@25°C)


Thermal Expansion /10-6 /°C@25°C


Specific Heat/ (J·g-1·K-1)


Hardness (Mohs)


Extinction Ratio




HGO offers Cospinel specifications:


<100> or <111>

Initial absorption coefficient


Initial transmission


Wavefront Distortion:

λ/8per inch @ 632.8 nm

Surface Quality:

20/10 Scratch/Dig MIL-O-1380A


< 10


< 10

Clear Aperture:

> 90%

Surface Flatness:

< λ/10 @ 632.8 nm


< 0.1 mm @ 45deg.


Upon customer request


AR/HR/PR coating upon customer’s request

Damage Threshold

750MW/CM2 at 1064nm, TEM00, 10ns, 10Hz

Quality Warranty Period

One year under proper use

Why Choose HGO ?

HG OPTRONICS.,INC. supplies very high quality of Co2+:MgAl2O4 Cobalt-doped magnesium aluminate spinel.The use of high quality starting materials for crystal growth, boule interferometry, and precise measurement of initial transmission and absorption using transmission spectroscopy and ZYGO measurements, assures that each crystal will comply with customer’s specification and perform well in laser system.

Tolerance of initial transmission can be well controlled within as high precision as 0.5% which could be very essential to some delicate laser systems. Besides, based on HGO’s advanced bonding technology, high quality of optical bonding kits between Er:Yb:glass and cospinel q-switch can also be supplied.

HGO could also provide high quality polishing and apply high laser induced damage threshold coating for the switch.and also for other related cavity lens and mirrors for the eye safe lasers systems.

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