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Terbium Gallium Garnet (TGG) is the right crystal material for Farady devices(Rotator and Isolator). The Farady ratator is made up of a TGG rod contained in a special designed magnet. The polarization of a light beam passing through the rotator makes rotation.The direction of rotation is only dependent on the direction of the magnetic field and not on the direction of propagation of the light beam.The optical isolator consists of a 45 degree rotator set between two suitably arrayed polarizers which allow a light beam to pass through in one direction only. With a combination of excellent properties, such as large verdet constant,low light loss, high thermal conductance and high light damage threshold,TGG is the unique material for Farady devices. It is widely used for YAG lasers and Ti:sapphire tunable lasers,ring lasers ,etc.

Basic Properties
Chemical formula Tb3Ga5O12
Lattice parameters a=12.355Å
Growth method CZ
Density 7.13g/cm3
Mohs hardness 8.0
Melting point°C 1725°C
Refractive index 1.954 at 1064nm
Thermal conductivity W/( °C*cm) 7.4W cm-1K-1
Polarized light magnetic constant rotation 0.12min/Oe.cm at 1064nm
Orientation [111] within 5 degrees
Wavefront Distortion (per inch of rod length) ?/8
Extinction Ratio 30 dB over 2/3 clear aperture
Diameter +0.000" / -0.002"
Length +0.010 / -0.010"
Chamfer 0.005" ± 0.003" @ 45°± 5°
Flatness ? / 10 wave @ 633 nm
Parallelism < 1 minutes of arc
Perpendicularity < 10 minutes of arc
Surface Quality 10 - 5 scratch-dig per MIL-0-13830A
Reflectivity < 0.25% at 1064 nm