Crystals Materials
Co:Spinel Crystal for radar, ranging and corneal diseases applications
  • Low optical losses in the wavelength range of 1.2µm ~ 1.6µm
  • The high absorption cross-section (3.5x10-19 cm2)
  • Passive Q-switch for Er:Glass lasers @1.54 µm
  • Surface Quality: 10/5 Scratch/Dig MIL-O-1380A
  • Parallelism: < 10″
  • Perpendicularity: < 5'
  • Clear Aperture: > 90%
  • Surface Flatness: < λ/10 @ 632.8 nm
  • Coating: AR/HR/PR coating upon customer's request
  • Quality Warranty Period: One year
  • Co:Spinel be a very effective passive Q-switch in lasers emitting in the range of 1,2 µm - 1,6 µm. Co:Spinel has a high absorption cross-section (3.5x10-19 cm2), which permits Q-switch operation of Er:glass laser (both flash-lamp and diode-laser pumped) without an intracavity focusing.

    Specifications of Co:Spinel Crystal
    Property Value
    Face Dimensions Tolerance +0,0/-0,1 mm
    Initial Transmission 50-99%@1535 nm
    Initial Transmission Tolerance ±1% (for values larger than 80%)
    Wavefront Distortion <λ/8 @ 632.8 nm
    Surface Flatness <λ/8 @ 632.8 nm
    Wavefront Distortion <λ/4 @ 632.8 nm
    Surface Quality 10/5 per MIL-O-13830A
    Parallelism < 10 arcsec
    Perpendicularity 10 arcmin
    Clear Aperture > 90%
    Chamfer < 0.1 mm @ 45°
    Coating AR/AR@1535 nm, R<0.15%; AR/AR@1340 nm, R<0.2%
    Physical and chemical properties
    Property Value
    Chemical Formula Co2+:MgAl2O4
    Crystal Structure Cubic
    Lattice Parameter 8.07 Å
    Mass Density 3.62 g/cm3
    Melting Point 2105°C
    Mohs Hardness 8.2
    Specific Heat/ (J/g/K) 5.9
    Thermal Expansion /(10-6/°C@25°C) 1.046
    Extinction Ratio 25 dB
    Thermal Conductivity/(W·cm-1·K-1@25°C) 0.033 W
    Refractive Index n=1.6948 @1.54 μm
    Optical properties
    Property Value
    Ground-state absorption cross-section GSA(10-19 cm2) 2.8 (±0.4)@1340 nm
    Excited state absorption cross-section ESA(10-20 cm2) 2.0 (±0.6)@1340 nm
    Ground-state absorption cross-section GSA(10-20 cm2) 3.5 (±0.4) @1540 nm
    Excited state absorption cross-section ESA(10-20 cm2) 1.0 (±0.6) @1540 nm
    Working wavelength 1200 ~ 1600 nm
    Damage Threshold > 750 MW/cm2

    Absorption and emission curves of Co:Spinel Crystal


    Stock specification list

    If need other specifications and quantities products, please contact us(
    Part Number Face size Initial Transmission @1064 nm Coating
    Co-Spinel-001 3.0*3.0 mm T0=80%~95% AR/AR@1535 nm
    Co-Spinel-002 4.2x4.2*1.5 mm T0=95% AR/AR@1540 nm
    Co-Spinel-003 5.0*5.0 mm T0=80%~95% AR/AR@1535 nm
    Co-Spinel-004 Ø6*1 mm T0=90% Uncoating


  • Anti-reflection coatings are available at your specified wavelength.
  • Be sure to wear laser safety goggles when checking optical path and adjusting optical axis.
  • To inquiry or order a finished Co:Spinel laser rod, please specify the specification listed above, for common application, we only need to know the main specification: initial transmission (T0), sizes, and coating. For special request, please specify specification in details for evaluation and fabrication.
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