Obviously the most important optical element in a Faraday Rotator and Isolator are the Magneto Optical Glass / Faraday Rotator Rod.
The characteristics that one looks for in a Faraday Rotator Optic, include a high Verdet constant,low absorption coefficient,low non-linear refractive index and high damage threshold. Also,to prevent self-focusing and other thermal related effects,the optic should be as short as possible.The two most commonly used materials for the 400-1600nm range are terbium doped borosillicate glass (MR3-2) and terbium gallium garnet crystal (TGG).But TGG crystal can't grow large size and too expensive
Specifications︰
In general,most of Magneto Optic Glass Elements produced by MR3-2 glass in view of cost,the sizes are available on request.
Magneto Optic Glass
Type MR3-2,Verdet constant-0.33min/Oe*cm at 632.8nm.
Type MR4 Verdet constant-0.38min/Oe*cm at 632.8nm
* Maximum inclusion size < 0.040 mm
* Maximum total inclusion cross
section < 0.04 mm2 per 100 cm*3
* Bubbles,inclusions,cord,striae:Optical grade
* Bulk laser damage threshold > 25 J/s.q.cm(20nsec pulse at 1064 nm)
* Strain birefringence (special-annealing) extinction ratio to perpendicular polarization ≥ 45 dB or better
* Strain birefringence at 632.8 nm < 2 nm/cm
Extinction ratio > 40dB
Magneto Optical Glass / Faraday Rotator Glass Element Feature
* Size from min. 0.90 mm to max.300 mm diameter,thickness max.50 mm.They are available to be made in a variety of forms including rods,slabs and disks
* Dimensional tolerance:+/- 0.05 mm for diameter
* Thickness tolerance:+/-0.10 mm for length
* Transitted wavefront ≤ 1/8 Lambda at 633 nm
* Polishing and faces flat ≤ 1/10 wave at 633nm
* Clear aperture exceeds central 95% of dimension
* Surface quality:20/10um scratch/dig or better(MIL-0-13830A,USA)
* Parallelism:End faces of the rotator rods are ground and polished < 60 seconds of arc.
( up to 5 arc seconds on request)
* Perpendicularity < 0.5 degree
* Chamfer: 0.10-0.30 mm at 45 +/- 5 degree
* Fine grind for rod body
* Transparence (uncoated) T% ≥ 86%
* Anti-Reflection Coatings for two sides
Anti-Reflection Coating T% ≥ 98%
* Pulsed Damage Threshold:>20 J/cm*2 at 1064 nm (20ns)
Advantages︰
*Magneto Optical Glass,the diameter from 1.00 mm to 300mm, other size and special shape can be provided.
* Magneto Optical Glass is widely used in Faraday Rotator,Optical Isolator and many kinds of sensors,polarimeters and instruments with higher sensitivity and stability.
