Optical waveguides – With optical coupler – Switch
Reexamination Certificate
1999-02-04
2001-06-05
Phan, James (Department: 2874)
Optical waveguides
With optical coupler
Switch
C385S015000, C356S128000, C356S136000
Reexamination Certificate
active
06243511
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to the field of optical devices and more particularly to a system and method for determining the condition of an optical signal.
BACKGROUND OF THE INVENTION
Optical signal loss may occur in a long length of an optical fiber or at an interface between two optical devices, such as at a connection between an optical fiber and another optical device. The condition of the optical signal communicated by the optical fiber to an optical device is important to the proper operation of the optical device. For example, if the optical signal is absent, attenuated, or otherwise degraded, the optical device may malfunction. Several techniques attempt to detect these conditions and provide protection switching to maintain communication.
One approach described in BellCore Technical Reference No. TR-NWT-001073 resolves this problem by splitting the optical signal into a primary component and a secondary component, and sampling the secondary component of the optical signal to determine the condition of the optical signal prior to communicating the optical signal to the optical device. This approach attenuates the optical signal by at least the amount of the secondary component and may create additional insertion losses in the optical signal.
SUMMARY OF THE INVENTION
In accordance with the present invention, a system and method for determining the condition of an optical signal is provided that substantially eliminates or reduces disadvantages and problems associated with previous techniques.
In accordance with one embodiment of the present invention, a system for determining the condition of an optical signal includes a first refractive material that receives an optical signal, and that has an interface with a second refractive material. The system further includes a signal monitoring circuit that determines the condition of the optical signal in response to a reflection generated at the interface by the optical signal.
Another embodiment of the present invention is a method for determining the condition of an optical signal that includes communicating an optical signal through a first refractive material having an interface with a second refractive material. The method continues by detecting a reflection generated at the interface by the optical signal. The method concludes by determining the condition of the optical signal in response to the reflection.
Yet another embodiment of the present invention is an optical apparatus that includes a first refractive material that receives a first optical signal and a second optical signal. The first refractive material has an interface with a second refractive material. The optical apparatus further includes a signal monitoring circuit that generates a control signal in response to a reflection generated at the interface by the first optical signal. A switchplate coupled to the second refractive material has a first position and a second position. An actuator coupled to the switchplate places the switchplate in a selected one of the first position and the second position in response to the control signal.
Technical advantages of the present invention include a signal monitoring circuit that determines the condition of an optical signal in response to a reflection generated by the optical signal at an interface between a first refractive material and a second refractive material. Prior attempts to sample an optical signal required splitting the signal into a primary component and a secondary component. This technique attenuates the optical signal by at least the amount of the secondary component that is split off for sampling and may create additional insertion losses in the optical signal. By determining the integrity of and, in one embodiment, the data communicated by the optical signal based upon a reflection signal generated by the optical signal at an interface between a first refractive material and a second refractive material, the present invention reduces the attenuation of the optical signal in comparison with prior techniques. In a particular embodiment, the reduction in attenuation may range from 1 dB to 6 dB.
Another important advantage of the present invention is an optical apparatus that includes the signal monitoring circuit and an optical device, such as an optical switch, to provide protection switching from a primary signal to a protection signal. The signal monitoring circuit controls locally the operation of the optical switch based upon a reflection generated by the primary signal at an interface between a first refractive material and a second refractive material associated with the optical switch. Prior attempts to provide protection switching using an optical switch include a centralized network management system in an optical network that receives information regarding the primary signal and centrally processes the information to control the protection switching. This technique requires substantial propagation time to receive and process data regarding the primary signal, to determine whether or not to activate the optical switch, and to communicate an appropriate control signal to the optical switch. In particular, the propagation times required by this technique often exceed switching tolerances permitted by the optical network. By processing the reflections generated by a primary signal at the optical switch using the signal monitoring circuit, the present invention controls the operation of the optical switch locally to provide protection switching. Accordingly, the present invention reduces the protection switching time of the optical switch. In one embodiment, the protection switching time of an optical switch using the present invention is reduced to less than ten microseconds, which may prevent detection and reporting of a fault in an optical network. Other technical advantages of the present invention are evident to one skilled in the art from the attached description, figures, and claims.
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Baker Botts L. L. P.
Optical Switch Corporation
Phan James
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