Due to the similar ionic radii of Erbium and Yttrium, the crystals with high Erbium content can be grown. YAG crystals highly substituted with erbium ions provide laser emission at 2.94μm wavelength. Er:YAG lasers are finding their application in the medical and dental areas owing to the high absorption of their emission wavelength (2.94μm) in the water and body fluids.

Standard Specifications of Nd:YAG
Host: Yttrium Aluminum Garnet (Y3A5O12
Dopant: Erbium (Er3+
Dopant Concentration: 50 Atomic %
Thermal expansion coefficient: 7.8x10-6/℃
Orientation: [111] crystallographic directions (± 5°)
Wavefront Distortion: l/2 wave per inch of length, as measured in a doublepass interferometer at 1mm
Dimension Tolerances: Rods with diameter: ±0.025 mm, Length: ±0.5 mm
Barrel Finish: 50 80 micro-inch (RMS) ,  grooved rod barrel are also available
Ends Finish: Surface Figure: <l/10 @ 633 nm 
Parallelism: < 10 arc seconds
Perpendicularity : < 2 arc minutes 
Surface quality: < 5 arc minutes 
Clear Aperture: > 10/5 Scratch / Dig per MIL-O-1380A
Chamfer: <0.1mm @ 45°
Clear Aperture: extend over the entire faces to the chamfered edges
Anti-Reflection End Coatings: less than 0.25% at 2.94μm