Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
1998-09-30
2001-05-01
Epps, Georgia (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C385S011000, C359S484010
Reexamination Certificate
active
06226115
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical circulator or switch. More particularly, the present invention relates to an optical circulator or switch which includes a birefringent wedge positioned between two Faraday rotators.
2. Description of the Related Art
Optical communication systems typically use an optical circulator or switch to control light travelling through the system.
Unfortunately, conventional optical circulators and switches are typically expensive to manufacture, have a relatively high number of components and are relatively large.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an optical circulator or switch which is inexpensive to manufacture, has a low number of components and is relatively small in size.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and, in part, will be obvious from the description, or may be learned by practice of the invention.
Objects of the present invention are achieved by providing an optical device which includes a birefringent tapered element, such as a birefringent wedge, positioned between first and second Faraday rotators, so that first and second lights having orthogonal polarizations travel through the first Faraday rotator, the birefringent tapered element and the second Faraday rotator, in order, and along travel paths which have a small angle between them, and, therefore, are not parallel to each other.
Moreover, objects of the present invention are achieved by providing an optical device including first and second birefringent wedges, and first and second Faraday rotators. The first and second birefringent wedges have crystal axes whose directions are rotated by 90° around the light traveling direction, and each have a bottom and a top and taper from the bottom to the top to form a wedge shape. The top of the first birefringent wedge is adjacent to the bottom of the second birefringent wedge, and the bottom of the first birefringent wedge is adjacent to the top of the second birefringent wedge. The first and second birefringent wedges are positioned between the first and second Faraday rotators so that light travels through the first Faraday rotator, the first birefringent wedge, the second birefringent wedge and then the second Faraday rotator, in order. Alternatively, a non-birefringent wedge, such as a glass wedge, can be used in place of either the first or second birefringent wedge.
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Cao Simon
Shirasaki Masataka
Epps Georgia
Fujitsu Limited
Spector David N.
Staas & Halsey , LLP
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