Terbium gallium garnet

Synthetic garnet

Terbium gallium garnet

General
Category| Synthetic mineral
Formula
(repeating unit)| Tb3Ga5O12
Identification
Optical properties| Faraday rotator material
Refractive index| 1.95
Other characteristics| Paramagnetic material

Terbium gallium garnet (TGG) is a kind of synthetic garnet, with the chemical composition Tb3Ga5O12.[1] This is a Faraday rotator material with excellent transparency properties and is very resistant to laser damage. TGG can be used in optical isolators for laser systems, in optical circulators for fiber optic systems, in optical modulators, and in current and magnetic field sensors.

TGG has a high Verdet constant which results in the Faraday effect. The Verdet constant increases substantially as the mineral approaches cryogenic temperatures.[2] The highest Verdet constants are found in terbium doped dense flint glasses or in crystals of TGG. The Faraday effect is chromatic (i.e. it depends on wavelength) and therefore the Verdet constant is quite a strong function of wavelength. At 632 nm, the Verdet constant for TGG is reported to be −131 rad/(T·m), whereas at 1064 nm it falls to −38 rad/(T·m).[3][4] This behavior means that the devices manufactured with a certain degree of rotation at one wavelength, will produce much less rotation at longer wavelengths. Many Faraday rotators and isolators are adjustable by varying the degree to which the amount of the Faraday rotator material is inserted into the magnetic field of the device. In this way, the device can be tuned for use with a range of lasers within the design range of the device.[5]

## See also[edit]

* Gadolinium gallium garnet
* Yttrium iron garnet
* Yttrium aluminium garnet

## References[edit]

1. ^ "Terbium Gallium Garnet - TGG" (PDF). Northrop Grumman. 2011.
2. ^ Hassaan Majeed; Amrozia Shaheen & Muhammad Sabieh Anwar (2013). "Complete Stokes polarimetry of magneto-optical Faraday effect in a terbium gallium garnet crystal at cryogenic temperatures". Optics Express. Optics InfoBase. 21 (21): 25148–58. Bibcode:2013OExpr..2125148M. doi:10.1364/OE.21.025148. PMID 24150356.
3. ^ Vojna, David; Slezák, Ondřej; Lucianetti, Antonio; Mocek, Tomáš (2019). "Verdet Constant of Magneto-Active Materials Developed for High-Power Faraday Devices". Applied Sciences. 9 (15): 3160. doi:10.3390/app9153160.
4. ^ Vojna, David; Duda, Martin; Yasuhara, Ryo; Slezák, Ondřej; Schlichting, Wolfgang; Stevens, Kevin; Chen, Hengjun; Lucianetti, Antonio; Mocek, Tomáš (2020). "Verdet constant of potassium terbium fluoride crystal as a function of wavelength and temperature". Opt. Lett. 45 (7): 1683–1686. Bibcode:2020OptL...45.1683V. doi:10.1364/ol.387911. PMID 32235973.
5. ^ "Optical Isolator Tutorial (Page 1 of 2)" (PDF). SeongKyeong Photonics / Thorlabs.

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Solid-state lasers

Distinct subtypes|

Semiconductor laser

Yttrium aluminium garnet|

* Nd:YAG laser
* Er:YAG laser
* Nd:Cr:YAG
* Yb:YAG
* Nd:Ce:YAG
* Ho:YAG
* Dy:YAG
* Sm:YAG
* Tb:YAG
* Ce:YAG
* Ce:Gd:YAG
* Gd:YAG

Glass|

* Nd:glass
* Ytterbium glass
* Er:Yb:Glass

Other gain media|

* Ruby laser
* Yttrium iron garnet (YIG)
* Terbium gallium garnet (TGG)
* Ti:sapphire laser
* Solid-state dye laser (SSDL/SSOL/SSDPL)
* Yttrium lithium fluoride (YLF)
* Neodymium-doped yttrium lithium fluoride (Nd:YLF)
* Yttrium orthovanadate (YVO4)
* Neodymium-doped yttrium orthovanadate (Nd:YVO4)
* Yttrium calcium oxoborate (YCOB)
* Nd:YCOB laser
* Ce:LiSAF
* Ce:LiCAF
* Cr:ZnSe
* U:CaF2
* Sm:CaF2
* Yb:SFAP

Structures|

* Diode-pumped solid-state laser (DPSSL)
* Fiber laser
* Figure-8 laser
* Disk laser
* F-center laser

Specific lasers|

* Trident laser
* ZEUS-HLONS (HMMWV Laser Ordnance Neutralization System)
* Nova (laser)
* Cyclops laser
* Janus laser
* Argus laser
* Shiva laser
* HiPER
* Laboratory for Laser Energetics
* Laser Mégajoule
* LULI2000
* Mercury laser
* ISKRA-6
* Vulcan laser

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