US 7,321,463 B2 | ||
In-line optical isolator | ||
Yoshiaki Takeuchi, Tokyo (Japan); Masaru Watanabe, Tokyo (Japan); and Ikuo Fukuzaki, Tokyo (Japan) | ||
Assigned to Osaki Electric Co., Ltd., Shinagawa-ku, Tokyo (Japan) | ||
Appl. No. 10/558,924 PCT Filed Jun. 23, 2004, PCT No. PCT/JP2004/008802 § 371(c)(1), (2), (4) Date Dec. 01, 2005, PCT Pub. No. WO2005/001548, PCT Pub. Date Jan. 06, 2005. |
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Claims priority of application No. 2003-185216 (JP), filed on Jun. 27, 2003; and application No. 2004-037930 (JP), filed on Feb. 16, 2004. | ||
Prior Publication US 2006/0268405 A1, Nov. 30, 2006 | ||
Int. Cl. G02B 5/30 (2006.01); G02B 27/28 (2006.01) |
U.S. Cl. 359—495 | 3 Claims |
1. An in-line optical isolator comprising:
a plurality of individual pairs of an input optical fiber for inputting a forward optical signal in a forward direction and
an output optical fiber for outputting a forward optical signal in a reflection direction that is input from the input optical
fiber;
a birefringent crystal positioned next to said input fibers and said output fibers for separating said forward optical signals
in the forward direction into ordinary rays and extraordinary rays and combining said ordinary rays and said extraordinary
rays in the reflection direction into said forward optical signals;
a half-wave plate positioned next to said birefringent crystal and provided along either the optical axes of said ordinary
rays and said extraordinary rays of said forward optical signals in the forward direction or the optical axes of said ordinary
rays and said extraordinary rays of said forward optical signals in the reflection direction and rotating the polarization
directions of said ordinary rays and said extraordinary rays reciprocally;
a lens positioned next to said half-wave plate for collimating said ordinary rays and said extraordinary rays in the forward
direction and collecting said ordinary rays and extraordinary rays in the reflection direction;
a Faraday rotator positioned next to said lens for rotating the polarization directions of said ordinary rays and said extraordinary
rays in both the forward direction and the reflection direction non-reciprocally; and
a reflector positioned next to said Faraday rotator for reflecting said ordinary rays and said extraordinary rays from the
forward direction to the reflection direction,
wherein the optical axis of said birefringent crystal is oriented so that the separation direction of said ordinary rays and
said extraordinary rays are arranged in a plane that is perpendicular to a plane including the optical axes of said input
optical fibers and said output optical fibers and
the optical axes of said ordinary rays and extraordinary rays of the forward optical signals in the forward direction and
the ordinary rays and extraordinary rays of the forward optical signals in the reflection direction are arranged at an equal
distance within each of these four rays from the optical axis of said lens at each point between said lens and said reflector.
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