Comparative Analysis of Nonlinear Crystals

High‑quality nonlinear optical and laser crystals for IR and THz bands

Comparative Analysis of Nonlinear Crystals

General Characteristics

Crystal	AgGaS₂	AgGaSe₂	HgGa₂S₄	PbGa₂S₄	BaGa₂GeSe₆	BaGa₂GeS₆	Ba₂Ga₈GeS₁₆	GaSe
Type	Silver-based	Silver-based	Mercury-based	Lead-based	Barium-based	Barium-based	Barium-based	Simple
Crystal System	Tetragonal	Tetragonal	Tetragonal	Tetragonal	Orthorhombic	Orthorhombic	Orthorhombic	Monoclinic

Optical Properties

Parameter	AgGaS₂	AgGaSe₂	HgGa₂S₄	PbGa₂S₄	BaGa₂GeSe₆	BaGa₂GeS₆	Ba₂Ga₈GeS₁₆	GaSe
Transparency Range	0.47–12.5 μm	0.75–18 μm	0.5–13 μm	2–5 μm	0.63–25 μm	0.63–25 μm	0.63–25 μm	0.594–16.45 μm
Nonlinear Coefficient	d₃₆ = 12.5 pm/V	d₃₆ = 33 pm/V	d = 26.8 pm/V	Not specified	d₁₁ = 23.6 pm/V	Not specified	Not specified	Not specified
Birefringence	0.0537 @ 1.06 μm	0.0228 @ 1.06 μm	-0.053	Not specified	0.25 @ 5 μm	Not specified	Not specified	Not specified
Laser Damage Threshold	20 MW/cm²	20 MW/cm²	1 J/cm²	Not specified	5.35 J/cm²	Not specified	Not specified	Not specified

Structural Properties

Parameter	AgGaS₂	AgGaSe₂	HgGa₂S₄	PbGa₂S₄	BaGa₂GeSe₆	BaGa₂GeS₆	Ba₂Ga₈GeS₁₆	GaSe
Symmetry Class	D₂d	D₂d	Tetragonal	Tetragonal	Orthorhombic	Orthorhombic	Orthorhombic	Monoclinic

Application Areas

AgGaS₂ and AgGaSe₂:
Second harmonic generation
Parametric oscillation
Frequency conversion
HgGa₂S₄:
Medical diagnostics
Gas analysis
Mid-IR spectroscopy
PbGa₂S₄:
Laser materials
Detector elements
IR optics
Barium-based crystals:
Broadband frequency conversion
Ultrafast pulse generation
Parametric oscillators
GaSe:
Nonlinear optics
High harmonic generation
THz generation

Key Findings

Each crystal type has unique characteristics:

Silver-based crystals (AgGaS₂, AgGaSe₂) offer high nonlinearity and broad transparency range
Mercury-based (HgGa₂S₄) provide high laser damage resistance and no oxidation in air
Lead-based (PbGa₂S₄) have wide bandgap and good thermal conductivity
Barium-based crystals (BaGa₂GeSe₆, BaGa₂GeS₆) exhibit high nonlinear coefficients
GaSe provides wide transparency range and unique nonlinear properties

The choice of material depends on specific requirements:

Required transparency range
Needed nonlinear properties
Laser damage threshold
Mechanical