Shin-etsu Chemical Co., Ltd.

Akira Yahagi

Shinji Makikawa

Toshiaki Watanabe

Masanori Ikari

Akio Ikesue

Takuto Matsumoto

An optical isolator for a wavelength band of 400 to 470 nm includes: a Faraday rotator having a Verdet constant equal to or greater than 750 Rad/T·m at a wavelength of 400 nm to 470 nm; and a hollow magnet provided on an outer periphery of the Faraday rotator, wherein a magnetic flux density B(T) applied to the Faraday rotator is within the range of the following formula (1), and an optical path length L(cm) over which the Faraday rotator is provided is within the range of the following formula (2): B≤0.40 (1); 0.26≤L≤0.50 (2). Thus, a miniaturized optical isolator which is transparent at violet and blue wavelengths of 400 to 470 nm is provided.

Optical isolator

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 satisfy0<  (1) and14.0≤≤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.

A transparent ceramic having terbium oxide (TbO) in a molar ratio of at least 40%; and at least one oxide selected among an yttrium oxide, a scandium oxide, and a lanthanide rare earth oxide, wherein (1) the crystal structure of the terbium-oxide-based ceramic does not contain a non-cubic-crystal phase, (2) the mean crystal particle diameter is in a range of 0.5 to 100 &#x3bc;m, and (3) the ceramic comprises a sintering auxiliary having no incidence of deposition of a non-cubic-crystal phase in the crystal structure of the terbium-oxide-based ceramic. This transparent ceramic makes a magneto-optical element that performs at least as well as terbium gallium garnet or other existing monocrystal materials. It also makes a functional element for an optical isolator in the infrared region between 500 nm and 1.5 &#x3bc;m having very little scattering and very few birefringence components.

Transparent ceramic, method for manufacturing same, and magneto-optical device

An optical isolator for use with a wavelength band of 600-800 nm is improved in that it has a Faraday rotator made of an oxide material in which said oxide material contains (TbR)Osuch that 0.5&#x2266;x&#x2266;1.0, and R is scandium, yttrium or any lanthanoid but Tb.

Optical isolator for a wavelength band of 600-800 nm

An optical module is provided that includes a Faraday rotator having a Verdet constant at a wavelength of 1.06 &#x3bc;m of at least 0.27 min/(Oe&#xb7;cm), a first hollow magnet disposed on the outer periphery of the Faraday rotator, and second and third hollow magnet units disposed so as to sandwich the first hollow magnet on the optical axis. The second and third hollow magnet units include 2 or more magnets equally divided in a direction of 90 degrees relative to the optical axis. A magnetic flux density B (Oe) applied to the Faraday rotator is in the range of 0.5&#xd7;10&#x2266;B&#x2266;1.5&#xd7;10. The Faraday rotator is disposed on a sample length L (cm) in the range of 0.70&#x2266;L&#x2266;1.10, and has an external diameter D (cm) in the range of 0.20&#x2266;D&#x2266;0.60.

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Annaka, Japan

Akira Yahagi