Cr4+:YAG
Chromium
Doped Yttrium Aluminum Garnet Crystal (Cr4+:YAG) is an excellent crystal
for passively Q-switching diode pumped or lamp-pumped Nd:YAG, Nd:YLF,
Nd:YVO4 or other Nd and Yb doped lasers at wavelength from 0.8 to 1.2
µm. It is chemically stable, durable, UV resistant, good thermal
conductivity, high damage threshold (> 500 MW/cm2) and easy to be operated.
Chromium(IV)-doped YAG (Cr:YAG) provides a large absorption cross section in the 0.9-1.2 micrometer spectral region, which makes it an attractive choice as a passive Q-switch for Nd-doped lasers. The resulting devices are solid-state, compact and low-cost. It has high damage threshold, good thermal conductivity, good chemical stability, is resistant to ultraviolet radiation, and is easily machined. It is replacing the more traditional Q-switching materials like lithium fluoride, organic dyes and color centers. The dopant levels range between 0.5-3 molar %.
It can be used for passive Q-switching the diode or lamp pumped Nd:YAG, Nd:YLF, Nd:YVO4, Yb:YAG, and other neodymium and yttrium doped lasers at wavelengths between 1000-1200 nm.
Cr:YAG can be also used for tunable lasers with output adjustable between 1350-1550 nm. It can generate ultrashort (down to femtoseconds range) pulses when pumped at 1064 nm by a Nd:YAG laser.
Cr:YAG was demonstrated in a non-linear optics application as a self-pumped phase-conjugated mirror in a Nd:YAG loop resonator. It provides compensation of both phase and polarization aberrations induced into the loop resonator.
Applications:
The preliminary experiments of Cr4+:YAG showed that the pulse width of passively Q-switched lasers could be as short as 5ns for diode pumped Nd:YAG lasers and repetition rate as high as 10kHz for diode pumped Nd:YVO4 lasers. Furthermore, an efficient green output @ 532nm, and UV output @ 355nm and 266nm were generated, after a subsequent intracavity SHG in KTP or LBO, THG and 4HG in LBO and BBO for diode pumped and passive Q-switched Nd: YAG and Nd: YVO4 lasers.
Basic Properties of Cr4+:YAG:
Chemical Formula: Cr4+:Y3Al5O12
Crystal Structure: Cubic Garnet
Density: 4.56g/cm^3
Hardness: Mohs 8.5
Thermal Conductivity: 12.13W/m.K
Refractive Index: 1.82 @ 1064 nm
Base state absorption cross section: 4.3x10^-18 cm^2
Emission state absorption cross section: 8.2x10^-19 cm^2
Fluorescence lifetime: 3.4µs
General Specifications
1) Aperture: 2x2mm to 15x15mm
2) Length: 0.1mm to 12mm
3) Initial Transmission: 10% to 99%
4) Surface Quality: better than 10/5 scratch/dig Per MIL-0-13830A
5) Parallelism: < 10"
6) Transimission Wavfront Distortion: < 1/8 @633nm
7) Coating: R<0.1%@1064nm or upon customer's specification
8) Damage Threshold: > 500 MW/cm2
9) Dopant Level: 0.5 mol% ~ 3 mol%
Diffusion Bonded Nd:YAG/Cr4+:YAG crystals are available
in OptoCity. These Diffusion Bonded Crystals are combined by optical contact
method and further bonded under high temperature.
