Del Mar Photonics - Newsletter Fall 2010 - Newsletter Winter 2010

Kirra Faraday Rotators and Isolators Models

Del Mar Photonics - Kirra Faraday Isolators and Rotators brochure

Broadband models have letter B at the end. For example model Kirra 8AFI38-800GB is a Faraday Isolator with 8 mm aperture for 800nm central wavelength made of Faraday Glass with 38 dB isolation

For custom Faraday Rotator or Isolator e-mails us at sales@dmphotonics.com
Please specify the following: wavelength of operation, beam size (required clear aperture), required isolation (38dB and 60dB are our standard).

Del Mar Photonics - Kirra Faraday Isolators and Rotators brochure - Faraday Q&A

1030-1080nm High Power Free Space Faraday Isolators - request a quote
General specifications:
Clear Aperture: 4 mm
Rotating Medium: TGG
Operating wavelength: 1030 nm - 1080 nm
Rotation Angle at Specified Wavelength : 45Deg +/- 30
Transmission With Polarizers: > 92%
Isolation : >=30dB
Pulsed Damage Threshold for 10nsec pulse: 5J/cm2


 

Del Mar Photonics - Kirra Faraday Isolator brochure - Faraday Isolator Models

Del Mar Photonics - Newsletter Fall 2010 - Newsletter Winter 2010

At high powers optical feedback can damage or disrupt the operation of a laser system. To reduce this feedback, an optical isolator can be inserted into the system. Faraday optical isolators (based on the Faraday effect) are passive unidirectional, nonreciprocal devices that utilize the phenomenon of magneto-optic rotation to isolate the source and protect the laser oscillator from reflections in an optical system. In other words, they basically act as an optical diode allowing the propagation of light in only one direction.

Faraday isolators (see Figure 1) typically consist of a Faraday rotator, two polarizers, and a body to house the parts. The Faraday rotator, in turn, consists of magnetooptically active optical material placed inside a permanent magnet (Nd-Fe-B).

In the Faraday optical isolator shown in Figure 2, the magneto-optical rod (located inside the Faraday rotator) is cut from glass (MOS-10) polished to flatness of /10, and has parallelism better than 10 arc seconds. It is anti-reflection coated with residual reflection <0.2% (each side) in the 765-835 nm range. The polarizers are air-spaced Glan prisms made of calcite. Entrance and exit faces of polarizers are anti-reflection coated with residual reflection of <0.3% in the range. Polarizer transmittance is >98%. This gives a total transmittance of better than 85% for the isolator.

Laser light (polarized or unpolarized) enters the input polarizer (P1) and is linearly polarized to 0°. Next, the linearly polarized light enters the Faraday rotator rod (magneto-optical rod). The plane of polarization rotates as the light propagates along the axis of the rod. The Faraday rotator is tuned to rotate the plane of polarization by 45°. (Changing the position of the rod allows tuning over a wavelength range from 765-835 nm.) The light then passes through the output polarizer (P2) whose transmission axis is also at 45°.

Any back reflected light re-enters the isolator through the output polarizer and becomes polarized at 45°. The back reflected light then passes through the Faraday rotator, which produces another 45° of rotation, and is now polarized at 90°, or horizontally, before being stopped by the input polarizer, still at 0°. Thus, the laser is isolated from its own reflections that may occur in the application part of the optical set.

This information was contributed by Sergey Egorov for Del Mar Photonics, located in San Diego, CA.

Del Mar Photonics - Kirra Faraday Isolator brochure - Faraday Isolator Models

Broadband Faraday Isolator for Femtosecond Ti:Sapphire Laser

Del Mar Photonics - Kirra Faraday Isolator brochure - Faraday Isolator Models

Wideband isolator model Kirra 5AFI38B-800C has 100 nm band: extinction ratio at 750/850 nm - 35dB, at 800 nm - 38 dB.
 

Isolation of the broadband Faraday isolator Kirra 5AFI38B-800C for femtosecond Ti:Sapphire laser as a function of wavelength.

Transmission of the broadband Faraday isolator Kirra 5AFI38B-800C for femtosecond Ti:Sapphire laser as a function of wavelength.

Del Mar Photonics - Kirra Faraday Isolator brochure - Faraday Isolator Models

Kirra Faraday Optical Isolators - 2-photon - 1030-1080nm High Power Free Space Faraday Isolators - 5AFI36- 800B broadband Faraday Isolator, to work with femtosecond Ti:sapphire lasers - Kirra Faraday Rotators and Isolators for Ti:Sapphire Laser - Kirra Faraday Rotators and Isolators for 1064 nm - Q&A - Faraday isolators for pulsed Nd:YAG laser system at 1064 nm