Optical add-drop multiplexer architecture with reduced effect of mirror edge diffraction
First Claim
1. Optical apparatus for switching multi-channel optical signals having spectral channels of different wavelengths, comprising:
- a plurality of input and output ports for optical signals having one or more of said spectral channels;
an optical beam expander and relay system adapted to receive the optical signals from one or more of the input ports, the optical beam expander and relay system being formed to convert the optical signals to spectral beams having a predetermined elongated beam profile;
a wavelength separator for spatially separating the spectral beams into constituent spectral channels; and
an array of channel micromirrors, each channel micromirror of the array being positioned to receive one of said constituent spectral channels, the micromirrors being rotatable about a switching axis to switch said one spectral channel to a selected output port;
wherein each channel micromirror is rotatable about an attenuation axis to vary the coupling of the switched spectral channel to the selected output port to control a power level of the spectral channel output at such selected port, wherein the attenuation axis is different from the switching axis,wherein the channel micromirrors and/or the input or output ports and/or wavelength separator are configured to reduce an increase in signal intensity of a spectral channel near side edges of a passband for that spectral channel relative to a central portion of the passband due to diffraction of that spectral channel from an edge of that spectral channel'"'"'s associated micromirror, wherein the edge is substantially parallel to the attenuation axis and the signal is attenuated by rotating the channel micromirror about the attenuation axis.
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Abstract
Effects of diffraction of a spectral beam from an edge of the micromirrors are reduced in order to optimize the passband in a wavelength selective switch. The effects of diffraction on the pass band may be reduced by appropriate modification of the edges of the micromirrors, by modification of the input and/or output ports to allow for attenuation by rotation of the micromirror about the switching axis, by using rotation of the micromirror about both the attenuation axis and the switching axis to achieve the desired level of attenuation, by inserting an aperture at a focal plane or external to the device to reduce the magnitude of the micromirror edge diffraction transmitted to any or all output ports, or by appropriate filtering of angular frequencies with a diffraction grating used to separate a multi-channel optical signal into constituent spectral beams.
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Citations
51 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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a plurality of input and output ports for optical signals having one or more of said spectral channels; an optical beam expander and relay system adapted to receive the optical signals from one or more of the input ports, the optical beam expander and relay system being formed to convert the optical signals to spectral beams having a predetermined elongated beam profile;
a wavelength separator for spatially separating the spectral beams into constituent spectral channels; andan array of channel micromirrors, each channel micromirror of the array being positioned to receive one of said constituent spectral channels, the micromirrors being rotatable about a switching axis to switch said one spectral channel to a selected output port; wherein each channel micromirror is rotatable about an attenuation axis to vary the coupling of the switched spectral channel to the selected output port to control a power level of the spectral channel output at such selected port, wherein the attenuation axis is different from the switching axis, wherein the channel micromirrors and/or the input or output ports and/or wavelength separator are configured to reduce an increase in signal intensity of a spectral channel near side edges of a passband for that spectral channel relative to a central portion of the passband due to diffraction of that spectral channel from an edge of that spectral channel'"'"'s associated micromirror, wherein the edge is substantially parallel to the attenuation axis and the signal is attenuated by rotating the channel micromirror about the attenuation axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method of optimizing passband in optical apparatus for switching optical signals of a multi-channel optical signal having constituent spectral channels of different wavelengths between input and output ports, comprising:
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spatially separating said multi-channel optical signal from one of the input ports into spectral beams corresponding to the constituent spectral channels; focusing the separated spectral channels onto corresponding channel micromirrors that switch the focused spectral channels 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; and reducing an increase in signal intensity of a spectral channel near the side edges of a passband for that spectral channel relative to a central portion of the passband due to effects of diffraction of that spectral channel reflected from an edge of that spectral channel'"'"'s associated micromirror, wherein the edge is substantially parallel to the attenuation axis and the signal is attenuated by rotating the channel micromirror about the attenuation axis. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51)
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Specification