Sumitomo Metal Mining Company, Ltd.

Kinya Oigawa

Nobuo Nakamura

[Object] To provide a polarization independent optical isolator enabling downsizing of a Faraday element and a magnet. [Solving means] The polarization independent optical isolator comprises: a pair of wedge-shaped birefringent crystal plates () provided in an optical path; and a Faraday element () made of a paramagnetic body and provided in the optical path between the wedge-shaped birefringent crystal plates. The pair of wedge-shaped birefringent crystal plates have inclined light-transmitting surfaces parallel to each other and non-inclined light-transmitting surfaces parallel to each other. The non-inclined light-transmitting surfaces are disposed to face the Faraday element. The polarization independent optical isolator is characterized in that: the paramagnetic body constituting the Faraday element has such a parallelogrammic cross section that light incident-emitting surfaces of the paramagnetic body are not parallel to the non-inclined light-transmitting surfaces of the pair of wedge-shaped birefringent crystal plates; and a right-angled portion () of each of the wedge-shaped birefringent crystal plates and a corresponding obtuse-angled portion () of the Faraday element are disposed on the same side with respect to an optical path central axis.

Polarization independent optical isolator

A composite lead frame in which an island formed with a greater diameter than that of a semiconductor device to be mounted is attached to a lead frame main body having leads being integrally protruded inward, the top ends of the leads are bonded with corresponding fine leads of the island at one ends thereof and lead terminals of the semiconductor device are connected respectively to the other ends of the corresponding fine leads, wherein the composite lead frame comprises an insulating sheet appended on one surface of the island and having the fine leads secured thereto being protruded outward and through holes disposed discretely passing through the insulating sheet and the island so that the wire bonding portions at the other ends of the fine leads are exposed.

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Noshiro, Japan

Kinya Oigawa