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Dive into the research topics where Hirotaka Kawai is active.

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Featured researches published by Hirotaka Kawai.


Japanese Journal of Applied Physics | 1996

Bi-Substituted Iron Garnet Films for Stable Faraday Rotation against Wavelength Variation in the 1.3 μm Band

Toshiyasu Suzuki; Hirotaka Kawai; Hiromitsu Umezawa

We report on the finding of a Bi-substituted Sm-containing iron garnet film ( La0.08Sm2.15Bi0.77Fe5O12) that realizes a high Faraday rotation stability against wavelength variation in the 1.3 µm band. This stability resulted from the peaks in the Faraday rotation at 1.24 µm and 1.38 µm due to Sm3+ ions. We calculated that such isolators could provide a 60 nm bandwidth in which the isolation would be maintained at 35 dB or higher. In addition, we discussed the relationship between the bandwidth and film composition.


Archive | 2000

Faraday rotation angle varying device

Hirotaka Kawai; Hiromitsu Umezawa


Archive | 1994

OPTICAL ISOLATOR FOR HIGH POWER

Kazuyoshi Hakamata; Hirotaka Kawai; Hiroshi Rikukawa; Hiromitsu Umezawa; 浩光 梅沢; 博貴 河合; 和喜 袴田; 弘 陸川


Archive | 2001

Farady rotation device and optical device comprising it

Teruhisa Sahashi; Hidenori Nakada; Hirotaka Kawai; Isao Kojima; Tsugio Tokumasu


Archive | 1998

Faraday rotation angle varying apparatus

Hirotaka Kawai; Hiromitsu Umezawa; Youichi Suzuki; Hidenori Nakada


Archive | 2004

Faraday rotation device and optical device using same

Teruhisa Sahashi; Hidenori Nakada; Hirotaka Kawai; Isao Kojima; Tsugio Tokumasu


Archive | 1995

Material for magneto-optical element and faraday rotator using the same

Toshiyasu Suzuki; Hirotaka Kawai; Hiromitsu Umezawa


Archive | 2011

REFLECTION TYPE VARIABLE OPTICAL ATTENUATOR

Hiroaki Ono; Hidenori Nakada; Hirotaka Kawai; Yuko Ota; Taro Nakamura


Archive | 1995

Magneto-optical element material formed of magnetic garnet single crystals

Hirotaka Kawai; Shinzo Fujii; Hiromitsu Umezawa


Archive | 2011

Reflective type variable optical attenuator

Hiroaki Ono; 博章 小野; Hidenori Nakada; 中田 英則; Hirotaka Kawai; 博貴 河合; Yuko Ota; 大田 猶子; Taro Nakamura; 中村 太郎

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