Optical waveguides – With optical coupler – Particular coupling structure
Reexamination Certificate
1998-08-13
2001-05-29
Nguyen, Thong (Department: 2872)
Optical waveguides
With optical coupler
Particular coupling structure
C385S003000, C385S145000
Reexamination Certificate
active
06240226
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of optical waveguides and, more particularly, to the materials used to construct optical waveguides.
BACKGROUND OF THE INVENTION
Current communications networks throughout the world have embraced the use of optical fiber waveguide technology to provide a conduit of transmission components for voice, video, and data signals. Optical networks offer far greater bandwidth and reliability than do conventional electronic networks. As a consequence, current research efforts have been directed to expanding the capabilities of optical waveguide technology at reduced cost to aid in the acceleration of the conversion of the present electrical communications networks to optical communications networks.
These optical communications networks are comprised of many different components. These include optical fiber cable, switches, attenuators, couplers, and many more such devices. Typically, these devices are comprised of a core surrounded by a cladding material. Both the materials used for the core and the cladding include silica or doped silica as well as many other similar materials. These materials are employed because they have a desirable index of refraction as well as other properties which facilitate their use.
Often times it is desirable to create specific effects on the propagation of the optical signal transmitted through these devices. For example, one such effect is to either modulate an optical signal or switch an optical signal from one waveguide to another. Consequently, there is a need for new optical structures which will facilitate the switching and modulation of an optical signal in an optical waveguide.
SUMMARY OF THE INVENTION
The present invention entails a Mach-Zender interferometer with a first waveguide core and a second waveguide core. The first and second waveguide cores are brought close together at a first directional coupler and a second directional coupler. The first waveguide core is surrounded by a first cladding and the second waveguide core is surrounded by a second cladding. The first cladding includes a section of polymer cladding in contact with the first waveguide core between the first and second directional couplers. Outside the polymer cladding section, the first waveguide core is surrounded by a standard cladding material which may include a substrate upon which the first waveguide core is formed and a silica cladding material covering the remaining surface area of the first waveguide core. The second waveguide core is similar to the first waveguide core except a standard cladding material is employed throughout its length. The polymer cladding has an index of refraction that varies with temperature.
A laser light which is transmitted into an input port may be transferred from the first waveguide core to the second waveguide core and vice versa in an identified proportion by altering the phase in one of the waveguides between the directional couplers. This is accomplished by altering the temperature of the polymer cladding resulting in a change in the index of refraction. Depending on the length of the section of polymer cladding, the phase of the laser light in the waveguide core bounded by the polymer cladding is altered by the desired amount.
The present invention may also be viewed as a method for switching laser radiation in an optical circuit comprising the steps of optically coupling a first waveguide core and a second waveguide core with a first directional coupler and a second directional coupler forming first and second joints, and then covering the first waveguide core with a first cladding that includes an identifiable area of a polymer cladding material, the identifiable area being between the first and second joints. Next the second waveguide core is covered with a second cladding and a laser beam is transmitted into the first waveguide core. Thereafter, further steps include splitting the laser beam in the first directional coupler at the first joint into a first split beam directed to the first waveguide core and a second split beam directed to the second waveguide core, and then controlling the temperature of the polymer cladding, thereby changing the index of refraction of the polymer cladding resulting in a change in the phase of the first split beam. Finally, the first and second split beams are recombined in the second directional coupler at the second joint, and the laser beam is transmitted out of the first and second waveguide cores according to a power ratio based upon the degree of the phase change of the first split beam.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention, as defined by the claims.
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Marcuse Dietrich
Presby Herman M.
Lucent Technologies - Inc.
Nguyen Thong
Thomas Kayden Horstemeyer & Risley, L.L.P.
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