Office for Technology Commercialization

Cavities for Inexpensive Faraday Rotators

Technology #20160217

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YIGFaraday rotator
Beth Stadler, PhD
Professor, Electrical and Computer Engineering
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Managed By
Kevin Nickels
Technology Licensing Officer 612-625-7289
Patent Protection

Provisional Patent Application Filed
Monolithically-Integrated TE-mode 1D Silicon-on-Insulator Isolators using Seedlayer-Free Garnet
Scientific Reports , Vol 7, Article number: 5820, 19-Jul-2017
Si-integrated ultrathin films of phase-pure Y3Fe5O12 (YIG) via novel two-step rapid thermal anneal
Materials Research Letters, Vol 5, (6); 01-Mar-2017; pp. 379-385

Faraday Rotator Cavities

A novel Faraday rotator architecture uses a high index substrate (such as the semiconductor, silicon (Si)) as one reflector (mirror or partial mirror) in the device and a quarterwave stack as the other reflector.  Most Faraday rotators require large garnet crystals or garnet thin films epitaxially grown onto other garnet substrates. However, these substances are expensive, non-abundant and not easily integrated, making it challenging to either manufacture large quantities of devices or to integrate them easily with other devices. This technology uses silicon as the substrate on which to grow the garnet for the Faraday rotator. The advantage to this approach is that silicon is naturally abundant and easily integrated.


  • Excellent nonreciprocal rotation of light
  • More easily manufactured (less cracking)
  • Substrate is naturally abundant and easily integrated
  • Additional features as needed


  • Atomic clocks
  • Faraday rotators/mirrors
  • Fiber interferometers
  • GPS atomic clocks
  • GPS systems
  • Light modulators
  • Optical devices
  • Optical fiber networks for telecommunications and geo-sensing
  • Optical isolators
  • Optical rotators (Faraday rotators/mirrors)
  • Preventing laser oscillators from damage
  • Preventing unwanted feedback
  • Spatial light modulators

Phase of Development

Prototype developed. Several working prototypes have been developed and measured to produce 10 degrees of Faraday rotation, which is an order of magnitude more than others have demonstrated.

Interested in Licensing?
The University relies on industry partners to scale up technologies to large enough production capacity for commercial purposes. The license is available for this technology and would be for the sale, manufacture or use of products claimed by the issued patents. Please contact Kevin Nickels to share your business needs and technical interest in this technology and if you are interested in licensing the technology for further research and development.