Faraday Rotator/Isolator

1. I have an EOT 1030-1080nm rotator/isolator. What is its bandwidth?

EOT's 1030-1080nm rotators/isolators can be optimized for any wavelength within the 1030-1080nm region. The bandwidth for any given specific wavelength in that region is ± 13nm. For example, if the rotator/isolator is optimized for 1053nm, it has a useable wavelength range of 1040nm-1066nm. Useable wavelength range is defined as the wavelength range over which the rotator/isolator will meet its published transmission and isolation specifications.

2. Can I use my 1030-1080nm rotator/isolator at 980nm or 800nm?

No. The 1030-1080nm rotators/isolators will not meet their published specifications at these wavelengths. The verdet constant of TGG is wavelength dependent. At shorter wavelengths, the verdet constant of TGG increases. At 980nm or 800nm, Faraday rotation would be considerably higher than 45°, resulting in poor isolation and transmission.

3. Why am I seeing fringes on my beam after it passes through my rotator/isolator.

This is an indication that of the beam being clipped due to overfilling of the clear aperture of the rotator/isolator. EOT recommends that the 1/e2diameter of your beam not exceed 2/3 of the clear aperture of your rotator/isolator. If you are seeing fringes, we recommend that you decrease the size of your beam.

4. Why is the isolation of my 1030-1080nm isolator decreasing over time?

This is usually a result of too much power being incident on the isolator or being rejected by the isolator. EOT's standard 1030-1080nm isolators are designed to handle up to 50W of average power, beyond that, absorption in the TGG can result in thermal lensing or other thermal related effects. EOT makes custom rotators specifically for lasers having >50W of average power. Please see the Custom Rotators section of this website for more information.

If more than 0.5W of average power is being rejected, EOT recommends that the escape ports be open to allow the rejected light to escape. If rejected powers of >0.5W are not allowed to escape and are instead contained within the isolator body, the isolator can heat up and degrade the performance of your isolator. When using the escape ports to allow rejected light to escape, it is important to properly terminate the beam. Please consult EOT's 1030-1080nm Rotator/Isolator Users Guide on this website for more information on the proper use of escape ports.

5. Why are the pulses from my femtosecond Ti:Sapphire laser being broadened after passing through my broadband rotator/isolator?

The pulse broadening is due to dispersion in the TGG. The Sellmeiers Equation for TGG can be found in the Faraday Rotator/Isolator Application Notes section of this website and can be calculated using the Sellmeiers Calculator on this website.

6. Why is my rotator/isolator not meeting specification at an operating temperature of 50°C when it was working fine at 25°C?

Both the TGG and magnets used in EOT's rotators/isolators are temperature dependent. As temperature increases, the verdet constant of TGG decreases and the fields generated by the magnets weaken, resulting in lower Faraday rotation. As temperature decreases, the verdet constant of TGG increases and the fields generated by the magnets strengthen, resulting in higher Faraday rotation. For more information, please see the Effects of Temperature on Faraday Rotators/Isolators in the Faraday Rotator/Isolator Technical Bulletins section of this website. If you are going to use your rotator/isolator at temperature other then room temperature or over a range of temperatures, we strongly encourage you to contact EOT to discuss this application.

7. Can I order an EOT laser diode isolator with an escape port for my injection locking application?

Yes. EOT offers our laser diode isolators with PBS cubes rather than Corning Polarcor polarizers for these applications. Please contact EOT for pricing and information on this option.

8. Can EOT do custom a baseplate or beamheight?

Yes. There will be an additional charge, but customized baseplates or special beamheights can be done. Please provide us with your specifications.

9. Are EOT's rotators/isolators vacuum compatible or space qualified?