All fiber polarization splitting switch
First Claim
1. An all fiber polarization splitting switch comprising:
- a polarization maintaining fiber comprising;
a first input port which receives a first optical signal;
a second input port which receives an optical pump signal, said pump signal being selectably present or absent at said second input port;
a first output port; and
a second output port;
a first polarization cross coupler formed on said polarization maintaining fiber in optical communication with said optical signal, said first polarization cross coupler separating said optical signal into first and second mutually perpendicular polarization states, each polarization state having approximately equal optical power;
a second polarization cross coupler connected in series with said first polarization cross coupler and in optical communication with said optical signal, said second polarization cross coupler selectably recombining said first and second polarization states into a combined optical signal having a first preferred polarization state or a second preferred polarization state in response to the presence or absence of said optical pump signal; and
a polarization splitting coupler connected to said polarization maintaining fiber, said polarization splitting coupler coupling said combined optical signal to said first output port if said combined optical signal has said first preferred polarized state and coupling said combined optical signal to said second output port if said combined optical signal has said second preferred polarization state.
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Accused Products
Abstract
An all-optical polarization splitting switch of the Mach-Zehnder type includes a polarization maintaining fiber, an optical input signal, an optical pump signal, two polarization cross couplers, and a polarization splitting coupler. The polarization maintaining fiber carries the optical signal and the optical pump signal while maintaining polarization orientation. The first polarization cross coupler splits the optical signal into two portions having mutually perpendicular polarization states which have approximately equal power. The optical pump signal, when present, changes the phase of the first portion of the optical signal with respect to the second portion of the optical signal. The second polarization cross coupler combines all the optical power into a combined optical signal. The polarization splitting coupler couples the combined optical signal into a first output port or a second output port in accordance with the polarization state of the combined signal. This configuration eliminates many of the signal phase discrepancies that occur due to thermal instability and unequal fiber lengths which the Mach-Zehnder type switch exhibits. One application for this invention is a polarization splitting switch for a distributed sensor array.
22 Citations
10 Claims
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1. An all fiber polarization splitting switch comprising:
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a polarization maintaining fiber comprising; a first input port which receives a first optical signal; a second input port which receives an optical pump signal, said pump signal being selectably present or absent at said second input port; a first output port; and a second output port; a first polarization cross coupler formed on said polarization maintaining fiber in optical communication with said optical signal, said first polarization cross coupler separating said optical signal into first and second mutually perpendicular polarization states, each polarization state having approximately equal optical power; a second polarization cross coupler connected in series with said first polarization cross coupler and in optical communication with said optical signal, said second polarization cross coupler selectably recombining said first and second polarization states into a combined optical signal having a first preferred polarization state or a second preferred polarization state in response to the presence or absence of said optical pump signal; and a polarization splitting coupler connected to said polarization maintaining fiber, said polarization splitting coupler coupling said combined optical signal to said first output port if said combined optical signal has said first preferred polarized state and coupling said combined optical signal to said second output port if said combined optical signal has said second preferred polarization state. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for switching an optical signal comprising the steps of:
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inputting a polarized optical signal into a polarization maintaining fiber having a first input port; selectively inputting an optical pump signal into a second input port of said polarization maintaining fiber; splitting said optical signal into a first signal portion having a first polarization state and a second signal portion having a second polarization state, said first signal portion having said first polarization state having approximately equal optical power to said second signal portion having said second polarization state; selectively causing a phase change in said first signal portion relative to said second signal portion when said optical pump signal is present; combining said first and second signal portions into a combined optical signal, said combined optical signal having a combined polarization state which depends upon said phase change; and coupling said combined optical signal; to a first output port when said combined polarization state results from said phase change when said optical pump signal is present; and to a second output port when said combined polarization state results from no phase change when said optical pump signal is not present. - View Dependent Claims (8, 9, 10)
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Specification