Optimized reconfigurable optical add-drop multiplexer architecture with MEMS-based attenuation or power management
First Claim
1. Optical apparatus for switching multi-channel optical signals having spectral channels of different wavelengths, comprising:
- fiber coupled collimators providing a plurality of input and output ports for optical signals having one or more of said spectral channels;
an anamorphic system receiving an optical signal from an input port of the fiber collimators and being formed to convert the optical signal to a beam having a predetermined beam profile;
a diffraction grating for spatially separating the beam into constituent spectral channel beams;
focusing optics for converting the constituent spectral channels into channel beams having an elongated channel beam profile; and
an array of biaxial channel micromirrors, the micromirrors having an elongated shape compatible with said elongated channel beam profile, and each micromirror of the array being positioned to receive one of said constituent spectral channels, the micromirrors being rotatable about a first switching axis to switch said one spectral channel to a selected output port, and being rotatable about a second attenuation axis to vary the coupling of the switched spectral channel to the selected output port to control the power level of the spectral channel output at such selected port.
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Abstract
A wavelength selective switch architecture for ROADMs for switching the spectral channels of a multi-channel, multi-wavelength optical signal between input and output ports employs a biaxial MEMS port mirror array for optimal coupling efficiency and ITU grid alignment, an anamorphic beam expander for expanding input optical signals to create an elongated beam profile, a diffraction grating for spatially separating the spectral channels, an anamorphic focusing lens system, an array of biaxial elongated channel MEMS micromirrors, a built-in Optical Channel Monitor, and an electronic feedback control system. The bi-axial channel micromirrors are rotatable about one axis to switch spectral channels between ports, and are rotatable about an orthogonal axis to vary the coupling of the spectral channel to an output port and control attenuation of the spectral signal for complete blocking or for a predetermined power level. The architecture affords hitless switching, near notchless operation, ITU channel alignment, high passband, stability over a broad temperature range, and minimum insertion loss through the optimal optical coupling efficiency enabled by the feedback control system.
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Citations
40 Claims
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1. Optical apparatus for switching multi-channel optical signals having spectral channels of different wavelengths, comprising:
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fiber coupled collimators providing a plurality of input and output ports for optical signals having one or more of said spectral channels;
an anamorphic system receiving an optical signal from an input port of the fiber collimators and being formed to convert the optical signal to a beam having a predetermined beam profile;
a diffraction grating for spatially separating the beam into constituent spectral channel beams;
focusing optics for converting the constituent spectral channels into channel beams having an elongated channel beam profile; and
an array of biaxial channel micromirrors, the micromirrors having an elongated shape compatible with said elongated channel beam profile, and each micromirror of the array being positioned to receive one of said constituent spectral channels, the micromirrors being rotatable about a first switching axis to switch said one spectral channel to a selected output port, and being rotatable about a second attenuation axis to vary the coupling of the switched spectral channel to the selected output port to control the power level of the spectral channel output at such selected port. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of optimizing optical apparatus for switching optical signals of a multi-channel optical signal having spectral channels of different wavelengths between input and output ports, comprising:
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converting the optical signals from one or more input ports into beams having predetermined beam profiles by anamorphically expanding the beams in orthogonal directions;
spatially separating said beams into constituent spectral channel beams having elongated channel beam profiles; and
focusing the separated spectral channel beams as elongated spots onto corresponding channel micromirrors that switch the focused spectral channel beams to one or more selected output ports, the channel micromirrors having an elongated shape and size that is compatible with the shape and size of said elongated spots, said focusing comprising aligning said elongated spots to be centered on said corresponding micromirrors. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method of aligning the spectral channels of a multi-channel optical signal onto corresponding channel micromirrors of an array of micromirrors in optical apparatus that switches the spectral channels to different output ports, comprising:
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directing a multi-channel optical signal comprising a plurality of spectral channels having different center wavelengths and a reference beam from an input port to a rotatable port mirror;
spatially separating the multi-channel optical signal from the port micromirror into constituent spectral channels, the separated spectral channels being spaced in accordance with their center wavelengths;
focusing the separated spectral channels as spots onto corresponding channel micromirrors of an array of micromirrors, the micromirrors of the array being spaced according to the separation between adjacent constituent spectral channels, and the location of a spot on a corresponding micromirror being determined by an angle of rotation of the port mirror;
directing the reference beam onto a detector, the reference beam having a location on the detector determined by the angle of rotation of the port mirror; and
controlling the rotation of the port mirror to position the reference beam on the detector at a predetermined location that aligns adjacent separated spectral channels onto corresponding adjacent channel micromirrors at a predetermined location on said channel micromirrors. - View Dependent Claims (39, 40)
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Specification