Yb:YAG Single Crystal (Ytterbium-Doped YAG) Technical Guide
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Yb:YAG Single Crystal — Complete Laser & Technical Specification Guide
Yb:YAG (Ytterbium-doped Y₃Al₅O₁₂) is one of the most important gain media for high-power solid-state lasers, diode-pumped lasers, and ultrafast femtosecond systems. With a simple two-level energy structure, low quantum defect, broad absorption bandwidth near 940 nm, and excellent thermal conductivity, Yb:YAG offers significantly higher efficiency and lower heat generation compared to Nd:YAG. This guide provides a full technical overview of how Yb:YAG crystals are grown, how to choose the correct Yb³⁺ doping concentration, what optical polishing is required for high-power operation, and how to specify custom Yb:YAG rods, slabs, and wafers for research or industrial lasers.
SECTION A — Growth Method for Yb:YAG Crystals
✔ Czochralski Growth (CZ)
The industry-standard for high-quality Yb:YAG boules, offering:
- Excellent Yb dopant uniformity
- Low birefringence and minimal scattering
- High thermal stability
- Large boule size availability
✔ Annealing
Post-growth annealing removes color centers and improves optical transmission.
SECTION B — Yb Doping Concentration & Optical Behavior
Typical Yb³⁺ doping levels:
| Application Type | Dopant Concentration |
|---|---|
| CW diode-pumped lasers | 5%–10% Yb |
| High-power DPSS lasers | 10%–15% Yb |
| Thin-disk lasers | 10% Yb typical |
| Ultrafast femtosecond lasers | 5%–7% Yb |
Why doping matters:
- Higher doping increases pump absorption
- But excessively high doping reduces fluorescence lifetime
- Optimal doping depends on pump wavelength (940 nm or 969 nm)
Optical Properties:
- Absorption peak: ~940 nm
- Emission wavelength: 1030 nm (broad band, ideal for ultrafast lasers)
- Low quantum defect: Efficient heat management
SECTION C — Orientation Specifications
Yb:YAG is cubic, but orientation still influences polishing and thermal load.
Common orientations:
- (111) — Most common; best mechanical stability
- (100) — Often used in high-power Yb:YAG systems
Orientation tolerance:
- Precision laser grade: ±0.2°
- Standard grade: ±0.5°
SECTION D — Polishing Requirements for Laser-Grade Yb:YAG
High-power lasers require extremely low scattering.
Laser-grade polishing:
- Scratch–dig: 20-10
- Flatness: λ/10 @ 632 nm
- Parallelism: <5 µm
- Surface roughness: Ra < 5 nm
- Available shapes:
- Rods (Φ3–10 mm)
- Slabs (thin or thick)
- Bonded/Yb:YAG thin-disk substrates
SECTION E — Coating Options for Yb:YAG Lasers
Common coatings:
- AR @ 940 nm (pump)
- AR @ 1030 nm (laser)
- HR @ 1030 nm (cavity mirror)
- Dual-band AR (940/1030 nm)
- High damage threshold coatings for femtosecond lasers
SECTION F — Key Applications of Yb:YAG Crystals
✔ Industrial Applications
- Cutting / welding / marking
- High-power diode-pumped lasers
- Thin-disk lasers
✔ Scientific & R&D
- Ultrafast femtosecond lasers
- Mode-locked oscillators
- High-energy amplifiers
✔ Defense / LIDAR
- Eye-safe laser pumping
- Long-range infrared systems
SECTION G — Yb:YAG Crystal Specification Table
| Parameter | Typical Value |
|---|---|
| Host material | Y₃Al₅O₁₂ |
| Doping ion | Yb³⁺ |
| Yb doping | 5–15% |
| Laser wavelength | 1030 nm |
| Pump wavelength | 940 nm / 969 nm |
| Transparency | 250–5500 nm |
| Refractive index | 1.82 @ 632 nm |
| Thermal conductivity | 10–14 W/m·K |
| Hardness | 8.5 Mohs |
| Growth method | Czochralski |
SECTION H — How to Order a Custom Yb:YAG Crystal
When ordering, specify:
- Yb³⁺ doping concentration: 5%, 7%, 10%, 15%
- Crystal orientation: (111) or (100), tolerance ±0.2–0.5°
- Shape: rod, disk, slab, wafer
- Dimensions: custom sizes
- Polishing: 20-10 laser-grade
- Coatings: AR @ 940 / 1030 nm
- Parallelism & flatness requirements
- Annealing (optional) for high-power use
Design-Realized can also provide:
- Bonded Yb:YAG thin-disk substrates
- Custom doping ratios
- High-damage-threshold coatings
- CNC machined holders for laser setups