Wavelength selective switch

An optical device for selectively directing a first signal and a second signal to a selected output, said optical device comprising:

• a birefringent optical system having a system input that receives the first signal and the second signal, and a system output to which said birefringent optical system transmits a superimposed signal formed by superimposing a first polarized signal and a second polarized signal, wherein said first polarized signal and said second polarized signal are polarized versions of the first signal and the second signal, respectively;
• and
• a polarization modulator coupled to said system output, whereby said polarization modulator selectively rotates a polarization state of said superimposed signal,
• wherein the birefringent optical system further comprises an input birefringent optical system coupled to a light incident side of the polarization modulator and an output birefringent optical system coupled to a light transmitting side of the polarization modulator, and wherein the input birefringent optical system further comprises a polarization beam splitter connected to the system input, said splitter separates the first signal into first signal polarization components and the second signal into second signal polarization components, and a first half-wave retarder disposed in a path of a polarized component for each of said first signal polarization components and said second polarization components to create first signal uniformly polarized components and second signal uniformly polarized components.

An optical device for selectively directing a first signal and a second signal to a selected output, said optical device comprising:

• a first polarization beam splitter for separating the first signal and second signal into first signal polarization components and second signal polarization components, respectively;
• a first half-wave retarder coupled to said polarization beam splitter, said first half-wave retarder causes all of said first signal polarization components and said second signal polarization components to be uniformly polarized in a first polarization state;
• a first grating coupled to said first half-wave retarder, for producing a plurality of first signal wavelength channels and a plurality of second signal wavelength channels;
• a second half-wave retarder coupled to said first grating, for causing said plurality of second signal wavelength channels to be uniformly polarized in a second polarization state;
• a first optical compensator coupled to said first grating, for causing an optical distance of said plurality of first signal wavelength channels to be substantially equal to an optical distance of said plurality of second signal wavelength channels;
• a first polarization beam combiner coupled to said optical compensator and said second half-wave retarder, for combining said plurality of first signal wavelength channels and said plurality of second signal wavelength channels into a plurality of superimposed wavelength channels;
• a focusing lens coupled to said polarization beam combiner;
• and
• an array of polarization modulators coupled to said focusing lens, each of said modulators has a switch state, wherein each superimposed wavelength channel is focused onto a predetermined modulator.

A method for selectively directing a first signal and a second signal to a selected output in an optical device that includes a birefringent optical system, said method comprising:

• providing an array of liquid crystal pixels, wherein each of said liquid crystal pixels includes a switch state;
• demultiplexing the first signal and the second signal to thereby form a plurality of first signal wavelength channels and a plurality of second signal wavelength channels, respectively;
• superimposing each first signal wavelength channel over its corresponding second signal wavelength channel to thereby form a plurality of superimposed wavelength channels;
• and
• focusing each superimposed wavelength channel onto a predetermined liquid crystal pixel,
• wherein said demultiplexing step further comprises:
• converting the first signal into a first parallel component and a first perpendicular component, and the second signal into a second parallel component and a second perpendicular component;
• converting said first parallel component and said first perpendicular component into two first perpendicular components, and said second parallel component and said second perpendicular component into two second perpendicular components;
• and
• demultiplexing said two first perpendicular components and said two second perpendicular components to form two sets of first signal perpendicular wavelength channel components and two sets of second signal perpendicular wavelength channel components, respectively.

A method for selectively directing a first signal and a second signal to a selected output in an optical device that includes a birefringent optical system, said method comprising:

• providing an array of liquid crystal pixels, wherein each of said liquid crystal pixels includes a switch state;
• demultiplexing the first signal and the second signal to thereby form a plurality of first signal wavelength channels and a plurality of second signal wavelength channels, respectively;
• superimposing each first signal wavelength channel over its corresponding second signal wavelength channel to thereby form a plurality of superimposed wavelength channels;
• and
• focusing each superimposed wavelength channel onto a predetermined liquid crystal pixel,
• wherein the step of superimposing further comprises converting the two sets of second signal perpendicular wavelength channel components into two sets of second signal parallel wavelength channel components and combining the two sets of first signal perpendicular wavelength channel components with said two sets of second signal parallel wavelength channel components, to form a first set of superimposed wavelength channels and a second set of superimposed wavelength channels.

An optical device for selectively directing a first signal and a second signal to a selected output, said optical device comprising:

• a birefringent optical system having a system input that receives the first signal and the second signal, and a system output to which said birefringent optical system transmits a superimposed signal formed by superimposing a first polarized signal and a second polarized signal, wherein said first polarized signal and said second polarized signal are polarized versions of the first signal and the second signal, respectively;
• and
• a polarization modulator coupled to said system output, whereby said polarization modulator selectively rotates a polarization state of said superimposed signal,
• wherein the input birefringent optical system further comprises a polarization beam splitter connected to the system input, so as to be able to separate the first signal into first signal polarization components and the second signal into second signal polarization components, and wherein a first half-wave retarder is disposed in a path of a polarized component for each of said first signal polarization components and said second polarization components to create first signal uniformly polarized components and second signal uniformly polarized components.