Cr:YAG Passive Q-Switch Crystal

22 May 2019

Description

Cr4+:YAG crystal can be used not only as Q-switch but also as gain medium because of its excellent physicochemical properties. The Q-switch operation of pulse and CW Nd:YAG lasers has been realized by using Cr4+:YAG as Q-switch, and the CW tunable and self-mode-locked operation has also been realized by using CR4 +: YAG as gain medium. Compared with the traditional saturable absorber, Cr: YAG is superior to the traditional saturable absorber in many aspects. The doping concentration of Cr4+ ion in Cr4+:YAG is as high as 1018 cm-3, which can effectively reduce the size of passive Q-switch elements. It is beneficial to achieve high optical conversion efficiency, integration, and compact passive Q-switch laser.

Parameter

Physical and Chemical Properties

Property	Value
Chemical formula	Cr4+:Y3Al5O12
Crystal structure	cubic – la3d
Lattice parameters, Å	12.01
Orientation	[100] or [110] < ±0.5°
Mass density	4.56 g/cm3
Mohs hardness	8.5
Young’s modulus	335 GPa
Tensile strength	2 GPa
Melting point	1970°C
Thermal conductivity	0.1213
Specific Heat/ (J·g-1·K-1)	0.59
Thermal Expansion /(10-6/°C@25°C)	7.8 7.7 8.2
Thermal shock resistance parameter	800 W/m
Extinction Ratio	25dB
Poisson Ratio	0.25
Refractive Index @1064 nm	1.83
Charge compensating ion	Ca2+, Mg2+

Optical Properties

Property	Value
Optical Density	0.1 to 0.8
Fluorescence lifetime	3.4μs
Concentrations	0.5 mol % ~ 3 mol %
Emission wavelength	1350 nm ~ 1600 nm
Absorption Coefficient	1.0 cm-1 ～ 7 cm-1
Ground state absorption cross section	4.3×10-18 cm2
Emission state absorption cross section	8.2×10-19 cm2
Transmission	10% to 90%
Coatings	AR≤ 0.2% @1064nm
Damage Threshold	> 500 MW / cm2

Polishing

Property	Value
Orientation Tolerence	< 0.5°
Thickness/Diameter Tolerance	±0.05 mm
Surface Flatness	<λ/8@632 nm
Wavefront Distortion	<λ/4@632 nm
Surface Quality	10/5
Parallel	10〞
Perpendicular	5ˊ
Clear Aperture	>90%
Chamfer	<0.1×45°
HR coating	<= 0.2% (@ 1340nm)
Maximum dimensions	22-1515 mm×20mm