Terbium Oxyhydroxide for Better Faraday Rotators

Market Overview:

This crystal growth method utilizes a hydrothermal process to produce single crystals for use in high-power industrial lasers. The global market for industrial lasers is projected to grow from $4.6 billion in 2015 to $6.3 billion by 2020, reflecting a sustained increase in manufacturing interest. The industry standard, Terbium Gallium Garnet (TGG), is manufactured with a coloring that reduces crystal performance and contains expensive Gallium, making it both commercially and technologically inefficient. Clemson University Researchers have developed a technique to grow Terbium Oxyhydroxide (TbOOH) crystals with improved optical properties, made only of Terbium. The resulting crystal shows improved performance as a faraday isolator in high-powered lasers.


Application                                                                   Stage of Development

Industrial Lasers, Manufacturing                                Prototype




  • Crystals utilize Terbium instead of Gallium feedstock, reducing manufacturing costs
  • Product can be used interchangeably with the current industry standard, making its adoption into existing laser designs easy
  • Crystals are transparent and demonstrate a Verdet constant almost twice that of the industry standard, improving performance while requiring less manufacturing material


Technical Summary

The Terbium Oxyhydroxide (TbOOH) crystal has been previously described, but was believed to be unsuitable for application in laser technology due to size constraints. Clemson University researchers have gone beyond traditional melt, flux, and pull methods to hydrothermally grow a crystal with the TbOOH formula in significantly larger sizes suitable for use as a faraday isolator. These crystals are colorless and transparent, eliminating the brown color defect found in commercially available TGG crystals. Preliminary data also shows a Verdet number of 70 for these TbOOH crystals as opposed to 40, which means smaller crystals can yield equal performance. To date, Clemson researchers have demonstrated growth of single TbOOH crystals 5-8 mm in size.

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Inventor:                       Joseph Kolis

Patent Type:                  Provisional

Serial Number:             62/532,662

CURF Ref No:              2017-004

Patent Information:
For Information, Contact:
Andy Bluvas
Technology Commercialization Officer
Clemson University Research Foundation
Joseph Kolis
Duminda Sanjeewa
Kyle Fulle
Photonic Crystals
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