AGSe Crystal
WaveQuanta

AGSe (AgGaSe2) Nonlinear Crystal for Mid-IR OPO and CO2 SHG, 0.73–18 µm

WQ-NLC-AGSE
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AGSe (silver gallium selenide, AgGaSe2) is a mid-infrared nonlinear crystal with band edges at 0.73 and 18 µm and a useful transmission range of 0.9–16 µm. Its broad phase-matching capability supports OPOs driven by several pump lasers: tuning over 2.5–12 µm has been obtained with a 2.05 µm Ho:YLF pump, and non-critical phase matching gives 1.9–5.5 µm output with 1.4–1.55 µm pumping. AGSe is also used for frequency doubling of CO2 lasers, and WaveQuanta supplies it with custom cuts and coatings.

Key Features

  • Transparency range 0.73–18 µm; useful transmission 0.9–16 µm
  • Nonlinear coefficient d36 = 39.5 pm/V at 10.6 µm
  • Absorption below 0.05 cm⁻¹ at 1.064 µm and below 0.02 cm⁻¹ at 10.6 µm
  • Non-critical phase matching for 1.9–5.5 µm output with 1.4–1.55 µm pumping
  • OPO tuning over 2.5–12 µm with a 2.05 µm Ho:YLF pump
  • Flatness λ/8 @ 633 nm, parallelism better than 30 arc sec
  • Standard apertures 5 × 5 mm and 8 × 8 mm, lengths 1–30 mm; custom sizes on request

Typical Applications

  • Second harmonic generation of CO and CO2 lasers
  • Mid-IR OPOs pumped at 1.4–1.55 µm or at 2.05 µm
  • Difference-frequency generation into the mid- and long-wave infrared
  • Sum- and difference-frequency mixing in the mid-IR

Dispersion (Sellmeier) Equations

no² = 4.6453 + 2.2057 / (1 - 0.1879/λ²) + 1.8577 / (1 - 1600/λ²)

ne² = 5.2912 + 1.3970 / (1 - 0.2845/λ²) + 1.9282 / (1 - 1600/λ²)

λ in µm

Standard Sizes

Size Cut / orientation Surface / coating Mount
5 × 5 × 1 / 5 mm θ = 51°, φ = 45° S1: AR @ 1.7–2.6 µm; S2: AR @ 5–16 µm —
5 × 5 × 1 mm θ = 55°, φ = 0° S1: AR @ 1.7–2.6 µm; S2: AR @ 5–16 µm —
5 × 5 × 6 mm θ = 51°, φ = 45° S1: HT @ 1.4–4.5 µm; S2: uncoated —
5 × 6 × 0.5 / 1 mm θ = 45°, φ = 45° AR/AR @ 1.7–2.8 + 6–14 µm —
9.5 × 8 × 12 mm θ = 49°, φ = 45° AR/AR @ 1.7–2.8 + 6–14 µm —
9.5 × 8 × 12 mm θ = 55°, φ = 45°, Type I AR/AR @ 1.7–2.8 + 6–14 µm —
5 × 5 × 0.5 mm θ = 45°, φ = 45° Polished, uncoated —
5 × 5 × 1 mm θ = 53.3°, φ = 0° Polished, uncoated —
5 × 5 × 1 mm θ = 65°, φ = 0° Polished, uncoated —
5 × 5 × 1.5 mm θ = 52°, φ = 45° Polished, uncoated —
5 × 5 × 1.5 mm θ = 58.8°, φ = 0° Polished, uncoated —
5 × 5 × 2 mm θ = 53.1°, φ = 45° Polished, uncoated —
5 × 5 × 5 mm θ = 51°, φ = 45° Polished, uncoated —
6 × 6 × 1.6 mm θ = 41.9°, φ = 45° Polished, uncoated —
8 × 8 × 1.5 mm θ = 53.1°, φ = 45° Polished, uncoated —
5 × 5 × 1.5 mm θ = 45°, φ = 45° Blank (unpolished) —
5 × 5 × 1.9 / 7 mm θ = 51°, φ = 45° Blank (unpolished) —
5 × 5 × 2 mm θ = 53.1°, φ = 45° Blank (unpolished) —
5 × 5 × 6 mm θ = 52°, φ = 0° Blank (unpolished) —
5 × 5 × 6.35 mm θ = 51.2°, φ = 45° Blank (unpolished) —
5 × 5 × 8.5 mm θ = 55°, φ = 0° Blank (unpolished) —
5 × 5 × 12 mm θ = 47.1°, φ = 45° Blank (unpolished) —
8 × 8 × 12.7 mm θ = 58°, φ = 45° Blank (unpolished) —

Availability of individual sizes changes; custom sizes, cut angles and coatings are available on request.

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Model: WQ-NLC-AGSE · Custom sizes, orientations and coatings on request — contact WaveQuanta for a quote and lead time.

Chemical Formula AgGaSe2
Crystal Structure Tetragonal
Cell Parameters a = 5.992 Å, c = 10.886 Å
Melting Point 851 °C
Density 5.700 g/cm³
Mohs Hardness 3–3.5
Transparency Range 0.73–18.0 µm
Useful Transmission Range 0.9–16 µm
Refractive Indices (no / ne) 2.7010 / 2.6792 @ 1.064 µm; 2.6134 / 2.5808 @ 5.3 µm; 2.5912 / 2.5579 @ 10.6 µm
Thermo-Optic Coefficients dno/dT = 15.0 ×10⁻⁵ /°C; dne/dT = 15.0 ×10⁻⁵ /°C
Absorption Coefficient < 0.05 cm⁻¹ @ 1.064 µm; < 0.02 cm⁻¹ @ 10.6 µm
Nonlinear Coefficient @ 10.6 µm d36 = 39.5 pm/V
Electro-Optic Coefficients γ41(T) = 4.5 pm/V; γ63(T) = 3.9 pm/V
Relative Dielectric Constant @ 25 MHz ε11(S) = 10.5; ε11(T) = 12.0
Damage Threshold @ ~10 ns, 1.064 µm 20–30 MW/cm² (surface)
Thermal Expansion Coefficient ∥c: −8.1 ×10⁻⁶ /°C; ⊥c: +19.8 ×10⁻⁶ /°C
Thermal Conductivity 1.0 W/(m·K)
Standard Cross Sections 5 × 5 mm, 8 × 8 mm
Length Range 1–30 mm
Dimension Tolerance (W ±0.1 mm) × (H ±0.1 mm) × (L +1/−0.5 mm)
Clear Aperture > 90% of central area
Flatness λ/8 @ 633 nm (T ≥ 1 mm)
Surface Quality 30-20 scratch/dig before coating; 60-40 after coating
Parallelism Better than 30 arc sec
Perpendicularity 10 arc min
Orientation Accuracy < 30 arc sec
Specification Sheet PDF — Download
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