Interference-based DWDM optical interleaver using beam splitting and selective phase shifting and re-combining

• US 20030099013A1
• Filed: 12/20/2000
• Published: 05/29/2003
• Est. Priority Date: 05/18/2000
• Status: Active Grant

• Current Assignee: QIN, YI
• Original Assignee: Hongchuan Wang, QIN, YI, Zhenpeng Su, Zhouzheng Shi
• Inventors: Su, Zhenpeng, Qin, Yi, Shi, Zhouzheng, Wang, Hongchuan
• Granted Patent: US 6,741,813 B2
• Time in Patent Office: Days
• US Class Current: 398/79
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/2706 as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters
• CPC Class Codes: G02B 6/29358 Multiple beam interferometer external to a light guide, e.g. Fabry-Pérot, etalon, VIPA plate, OTDL plate, continuous interferometer, parallel plate resonator G02B6/29347, G02B6/29349, G02B6/2935, G02B6/29361 take precedence; resonator evanescently coupled to light guide G02B6/29335
• CPC Class Codes: G02B 6/2938 for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems

Abstract

An interleaver comprises a serial array of optical elements to which a multichannel, continuous spectrum, composite signal is input and two multichannel, non-continuous spectrum, composite signals are output. Two embodiments are disclosed. One such embodiment provides output composite signals which are spectrally symmetric in that each such non-continuous spectrum contains the same number of channels albeit of alternating center wavelengths. The other such embodiment provides output composite signals which are spectrally asymmetric in that each such non-continuous spectrum contains either a different number of channels or an equal number of channels of narrower or wider passband. Each of the preferred embodiments comprises an array of optical elements which split the input composite signal into components of different polarization states, selectively add phase shifts to some of these components and recombine them a number of times. The inventive arrays operate on the incident composite signal light beam to produce interference effects which attenuate the unwanted wavelength components in each composite output signal and reinforce the desired wavelength components.

Claims

1. An optical signal interleaver for receiving an optical composite signal input having a continuous spectrum of multiple channels each having a center wavelength and generating a pair of optical composite signal outputs each having a non-continuous spectrum of multiple channels having respective center wavelength;

the interleaver comprising;

a serial array of optical components through which beams of optical signals may pass first in one direction and then be reflected to pass in the opposite direction;

said optical components having at least one polarization beam splitter, configured for splitting said beams into a greater number of beams based upon respective polarizations of said beams, at least one beam combiner, configured for recombining said split beams into a smaller number of beams based upon respective polarizations of said beams;

at least one phase shifter placed between said at least one beam splitter and said at least one beam combiner for shifting the phase of some selected said split beams before they are recombined with split beams without phase shift;

at least one beam processor to adjust the fraction of the light beam components with different relative phase shift to achieve a spectral interference pattern such that unwanted center wavelength channels are attenuated while desired center wavelength channels are reinforced.

2. The interleaver recited in claim 1 wherein said at least one splitter, phase shifter, combiner, and processor are selected to provide said pair of outputs with symmetric spectra.

3. The interleaver recited in claim 1 wherein said at least one splitter, phase shifter, combiner, and processor are selected to provide said pair of outputs with asymmetric spectra.

4. An apparatus for receiving a composite optical signal defined by a plurality of distinct channels having spaced center wavelengths in a continuous frequency spectrum;

the apparatus generating two separate output optical signals from the received signal;

the apparatus comprising;

a wavelength-dependent serial array of optical elements for segregating said received signal into said two separate output optical signals having non-continuous spectra;

one of said output signals having a greater number of said distinct channels than the other of said output signals.

5. The apparatus recited in claim 4 wherein the non-continuous spectrum of one of said output signals is the complement of the non-continuous spectrum of the other of said output signals.

6. The apparatus recited in claim 4 wherein the combined non-continuous spectra of said two output signals contain all of said distinct channels of said continuous frequency spectrum of said received optical signal.

7. The apparatus recited in claim 4 wherein each of said non-continuous spectra of said output optical signals comprises a plurality of passbands that are spaced from one another in frequency;

the number of said distinct channels in each of said passbands of one of said output signals being greater than the number of said distinct channels in each of said passbands of the other of said output signals.

8. A method for demultiplexing a composite optical signal with different center wavelengths represented by λ

₁, λ

₂, λ

₃, λ

₄, . . . λ

_n where n is a positive integer and said wavelengths are equally spaced, comprising steps of;

a) receiving said composite optical signal into a serial optical component array configured as an asymmetric wavelength slicing device through a device input port; and

b) slicing said composite signal and extracting a first composite optical signal comprising a first set of channels λ

₁, λ

_a, λ

_b, λ

_c, . . . λ

_n-1 through a first output port, and a second composite optical signal comprising a second set of channels λ

₂, λ

_d, λ

_e, λ

_f, . . . λ

_n through a second output port wherein said second set of data channels is complimentary to said first set of data channels and a spacing (λ

₁-λ

_a) between λ

₁ and λ

_a is different from a spacing (λ

₂-λ

_d) between λ

₂ and λ

_d.

12. The method recited in claim 8 wherein said slicing step comprises the step of splitting said composite optical signal into separate beams of light, selectively phase shifting some of said beams and re-combining said beams to create interference effects.

9. A method for demultiplexing a composite optical signal with different center-wavelengths represented by λ

₁, λ

₂, λ

₃, λ

₄, . . . λ

_n where n is a positive integer and the wavelengths are equally spaced, comprising steps of;

a) receiving said composite optical signal into a serial optical component array configured as an asymmetric wavelength slicing device through a device input port; and

b) slicing said composite signal and extracting a first composite optical signal comprising a first set of channels λ

₁, λ

₃, λ

₅, λ

₇, . . . λ

_n-1 through a first output port and a second composite optical signal comprising a second set of channels λ

₂, λ

₄, λ

₆, λ

₈, . . . λ

_n through a second output port wherein said second set of data channels is complimentary to said first set of data channels but having a different bandwidth.

13. The method recited in claim 9 wherein said slicing step comprises the steps of splitting said composite optical signal into separate beams of light, selectively phase shifting some of said beams and re-combining said beams to create interference effects.

10. An asymmetric wavelength slicing device having a serial optical component array for demultiplexing a composite optical signal with different center-wavelengths represented by λ

₁, λ

₂, λ

₃, λ

₄, . . . λ

_n where n is a positive integer and the wavelengths are equally spaced, comprising at least an input port and two output ports,

said composite signal being sliced into a first composite optical signal comprising a first set of channels λ

₁, λ

_a, λ

_b, λ

_c, . . . λ

_n-1 through a first output port, and a second composite optical signal comprising a second set of channels λ

₂, λ

₁, λ

_e, λ

_f, . . . λ

_n through a second output port wherein said second set of data channels is complimentary to said first set of data channels, but the spacing between λ

₁ and λ

_a is different from the spacing between λ

₂ and λ

_d.

14. The slicing device recited in claim 10 wherein said array comprises at least one polarization beam splitter, at least one phase shifter, at least one beam combiner and at least one beam processor.

11. An asymmetric wavelength slicing device having a serial optical component array for demultiplexing a composite optical signal with different center-wavelengths represented by λ

₁, λ

₂, λ

₃, λ

₄, . . . λ

_n where n is a positive integer and the wavelengths are equally spaced, comprising;

at least an input port and two output ports, said composite signal being sliced into a first composite optical signal comprising a first set of channels λ

₁, λ

₃, λ

₅, λ

₇, . . . λ

_n-1 through a first output port, and a second composite optical signal comprising a second set of channels λ

₂, λ

₄, λ

₆, λ

₈, . . . λ

_n through a second output port wherein said second set of data channels is complimentary to said first set of data channels, but the bandwidth is different from the bandwidth of said first set of data channels.

15. The slicing device recited in claim 11 wherein said array comprises at least one polarization beam splitter, at least one phase shifter, at least one beam combiner and at least one beam processor.

16. A method for demultiplexing an input composite optical signal having a continuous spectrum of wavelength channels, into at least two output composite optical signals having complementary non-continuous spectra;

the method comprising the steps of;

a) splitting said input composite optical signal into a plurality of spacially separated beams of light that travel in a first direction through an array of optical components;

b) phase shifting some of said split beams by selected magnitudes of phase compensation during said travel;

c) re-combining split beams;

d) repeating splitting, phase shifting and re-combining of said beams of light until by selected beam interference, desired wavelength channels are reinforced and undesired wavelength channels are attenuated in each such output composite optical signal.

17. The method recited in claim 16 wherein said repeating step comprises the step of reversing the direction of travel of said beams of light at least once.