Success in Development of Garnet-type Single Crystal for Use in Optical Isolators

Application to High Output, Wideband Laser Light Sources

2009.10.22

National Institute for Materials Science
Fujikura Ltd.

A group headed by Kiyoshi Shimamura, Group Leader and Garcia Villora, Senior Researcher of the Frequency Conversion Group, Optronic Materials Center of the National Institute for Materials Science, in joint work with Kunihiro Naoe, Manager, of Fujikura Ltd., succeeded in the development of a garnet-type single crystal for use in optical isolators, which are applied to high output, wideband laser light sources.

Abstract

  1. A group headed by Kiyoshi Shimamura, Group Leader and Garcia Villora, Senior Researcher of the Frequency Conversion Group, Optronic Materials Center of the National Institute for Materials Science (President: Sukekatsu Ushioda), in joint work with Kunihiro Naoe, Manager, of Fujikura Ltd. (President: Yoichi Nagahama), succeeded in the development of a garnet-type single crystal for use in optical isolators, which are applied to high output, wideband laser light sources.
  2. In recent years, as progressively higher output light sources have been applied to precision processing using laser processing machines with high output light sources, it has become necessary to stabilize and prevent the destruction of the light source. Likewise, in order to cope with the increasing volume of information in optical telecommunications using optical fiber cables, it has also become necessary to stabilize and prevent the destruction of the light source so as to realize higher light source output and expanded bandwidth and to improve the reliability of the transmitted information. Because optical isolators are one key device for stabilizing the light source and preventing its destruction, magnetic garnet-type single crystals, which offer superior performance and cost, had been necessary.
  3. The crystal developed in this work is a terbium-scandium-lutetium-aluminum-garnet single crystal. In comparison with the conventional terbium-gallium-garnet single crystals, it was found that this crystal has an increased Faraday rotation angle exceeding a maximum of 30%, depending on the wavelength. Growth of large-scale single crystals is also easy, and the crystals possess excellent wavelength transmission characteristics. As a result, high expectations are placed on the newly-developed crystal as a magnetic garnet single crystal for use in optical isolators suitable for laser light sources with higher outputs and wider bandwidth, while also making it possible to reduce costs. In the future, the team intends to carry out research aimed at obtaining even larger scale and higher quality with this crystal.
  4. This research achievement is scheduled for presentation at various international conferences and elsewhere, beginning with the Spring Meeting of the Japan Society of Applied Physics (JASP) in March 2010 and the Annual Meeting of The Ceramic Society of Japan, also in March.
"Fig: Garnet-type Single CrystalGarnet-type Single Crystal" Image

Fig: Garnet-type Single CrystalGarnet-type Single Crystal