Free-space/arrayed-waveguide router
First Claim
Patent Images
1. An optical apparatus comprisingan optical arrayed waveguide router (AWR) for receiving at an input wavelength division multiplexed (WDM) signal having M wavelength channels, M>
- 1, and a one dimensional array of N outputs, 1<
N<
M, for outputting the WDM signal within the free spectral range (FSR) of the AWR, each output n, where 1≦
n≦
N, including a partially demultiplexed signal having a plurity of wavelength channels n, n +N, n+2N, . . . n+{M/N−
1}N of the WDM signal, and a free-space optical wavelength channel demultiplexer for receiving each of the partially demultiplexed signal channels and for producing therefrom M wavelength channels, each of the M wavelength channels being outputted at a different one of M outputs.
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Abstract
A router combines free-space and guided wave optics to drastically increase the number of channels used in WDM transmission systems. The two-stage router uses the partial demultiplexing characteristic of an arrayed waveguide router (AWR) combined with a free-space optical router to fully demultiplex an input WDM signal. The two-stage router can be used to obtain output wavelength signals in either one- or two-dimensional arrays.
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Citations
14 Claims
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1. An optical apparatus comprising
an optical arrayed waveguide router (AWR) for receiving at an input wavelength division multiplexed (WDM) signal having M wavelength channels, M> - 1, and a one dimensional array of N outputs, 1<
N<
M, for outputting the WDM signal within the free spectral range (FSR) of the AWR, each output n, where 1≦
n≦
N, including a partially demultiplexed signal having a plurity of wavelength channels n, n +N, n+2N, . . . n+{M/N−
1}N of the WDM signal, anda free-space optical wavelength channel demultiplexer for receiving each of the partially demultiplexed signal channels and for producing therefrom M wavelength channels, each of the M wavelength channels being outputted at a different one of M outputs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
a first lens for collimating the partially demultiplexed signal channels from the one-dimensional array of N outputs onto a grating; said grating being a transmissive grating for demultiplexing each of the one-dimensional array of partially demultiplexed signals into individual wavelength channels so as to form a two-dimensional array of wavelength channels;
a second lens for focusing the two-dimensional array of wavelength channels onto a two-dimensional array of elements.
- 1, and a one dimensional array of N outputs, 1<
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3. The apparatus of claim 2 wherein the two-dimensional array of elements is a two-dimensional array of mirror elements, one or more mirror elements being individually controlled to reflect one of the two-dimensional array of wavelength channels back through the second lens, the transmissive grating, the first lens to said AWR when a first control signal is applied to said one or more mirror elements.
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4. The apparatus of claim 3 wherein when a second control signal is applied to a mirror element that mirror element reflects its wavelength channels back through
a third lens for focusing the reflected wavelength channel onto a second grating; -
said second grating being a transmissive grating for multiplexing together into a combined signal each reflected wavelength channel which originated from the same partially demultiplexed signal;
a fourth lens for focusing the combined signal onto a second AWR.
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5. The apparatus of claim 4 further including
a first circulator for coupling signals to and from the AWR and a second circulator for coupling signals to and from the second AWR. -
6. The apparatus of claim 5 wherein the AWR and the second AWR each include
an input waveguide for receiving the WDM signal, a first free space region connected to both the input waveguide and to a first end of a set of chirped waveguides, a second free space region connected to both a second end of the chirped waveguides and to a set of N output waveguides which terminate in a one-dimensional array of N outputs. -
7. The apparatus of claim 5 where the one-dimensional array of elements includes a one-dimensional array of optical fibers.
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8. The apparatus of claim 5 where the one-dimensional array of elements is a one-dimensional waveguide array formed together with the AWR on a waveguide unit.
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9. The apparatus of claim 3 further including
a first circulator for coupling signals to and from the AWR. -
10. The apparatus of claim 1 wherein the free-space optical wavelength channel demultiplexer includes
a first lens for focusing the partially demultiplexed signal channels from the one-dimensional array of N outputs onto a grating; -
said grating being a reflective grating for demultiplexing each of the one-dimensional array of partially demultiplexed signals into individual wavelength channels so as to form a one-dimensional array of wavelength channels;
said lens focusing the one-dimensional array of wavelength channels onto a one-dimensional array of elements.
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11. The apparatus of claim 1 wherein the M outputs are arranged in a one-dimensional array.
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12. The apparatus of claim 1 wherein the M outputs are arranged in a two-dimensional array.
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13. An optical apparatus comprising
a planar optical arrayed waveguide router (AWR) for receiving an input wavelength division multiplexed (WDM) signal having M wavelength channels, M> - 1, and an output,
a lens for collimating a signal from the AWR output onto a free-space optical wavelength channel demultiplexer, and the free-space optical wavelength channel demultiplexer being oriented in a different plane than the AWR, for receiving the collimated output from the lens and for producing therefrom M wavelength channels, each of the M wavelength channels being outputted at a different one of M outputs. - View Dependent Claims (14)
an input waveguide for receiving the WDM signal, a first free space region connected to both the input waveguide and to a first end of a set of chirped waveguides, a first side of a second free space region connected to a second end of the chirped waveguides, and a second side of the second free space region being formed having a straight line edge to serve as the output of the AWR.
- 1, and an output,
Specification