Optical isolator
AssigneeShin-Etsu Chemical Co., Ltd.
InventorsAkira Yahagi, Masanori Ikari, Takuto Matsumoto
Life of this patent
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Abstract
An optical isolator includes a Faraday rotator including a trivalent ion exchange TAG (terbium-aluminum garnet), and arranged around the Faraday rotator, a central hollow magnet and a first and a second hollow magnet units arranged to sandwich the central hollow magnet in an optical axis direction. A magnetic flux density B [T] in the Faraday rotator and an optical path length L [mm] where the Faraday rotator is arranged satisfy 0<B (1) and 14.0≤L≤24.0 (2). The optical isolator, compared with a conventional Faraday rotator such as a terbium-gallium garnet (TGG) crystal, contributes to reduction of a thermal lensing effect, being a pending problem, in a high-output fiber laser.
Claims7
An optical isolator comprising:
- a Faraday rotator comprising a trivalent ion exchange TAG (terbium-aluminum garnet), and
- arranged around the Faraday rotator, (i) a central hollow magnet and (ii) a first hollow magnet unit and a second hollow magnet unit each arranged to sandwich the central hollow magnet in an optical axis direction,
- wherein:
- a magnetic flux density B [T] in the Faraday rotator and an optical path length L [mm] where the Faraday rotator is arranged satisfy:
- 0<B (1) and
- 14.0≤L≤24.0 (2),
- the central hollow magnet and the first and second hollow magnets are neodymium-iron-boron (NdFeB) type magnets, and
- the Faraday rotator has, at an optical path length of L≤24.0 mm, optical characteristics comprising:
- an absorption coefficient of 0.001 cm−1 or less,
- an extinction ratio of 25 dB or more, and
- a lower insertion loss of 0.04 dB or less.
Dependencies are inferred from the claim text.