Traitement en cours

Veuillez attendre...

Paramétrages

Paramétrages

Aller à Demande

1. WO2000036446 - ROUTEURS OPTIQUES A SELECTIVITE DE LONGUEURS D'ONDES

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

CLAIMS

We claim:

A system for switching of individual optical wavelength bands in a multi-wavelength optical transmission system comprising:
a plurality of non-evanescent wavelength selective optical couplers each having two pairs of terminals coupled to a common reduced diameter waist region including a periodic grating which diverts with low insertion loss signals of selected wavelengths received at one terminal of a pair to the other terminal of the pair, while passing through signals of other than the selected wavelengths, thereby both bandpass filtering and redirecting signals, and
circuit connections including a multi- wavelength line coupled to all the couplers at selected terminals of the couplers, the couplers being arrayed in a selected pattern of wavelength selectivity to selectively redistribute the selected wavelength signals in a chosen manner.

2. A system as set forth in claim 1 above, including in addition an add/drop optical line, each of the lines including a series of couplers in which pairs of couplers in the different lines are selective at like wavelengths bands, and the system further includes crossover switches interconnecting the paired couplers, and a controller unit coupled to operate the crossover switches for routing the signals in selected wavelength bands.

3. A system as set forth in claim 1 above, wherein the couplers are connected in series to the multi-wavelength line and the couplers each are characterized by gratings providing passbands for diverted signal wavelengths which encompass more than one discrete signal bearing wavelength and which have shaφ rolloff characteristics at the edges of the passbands, there being substantially less spectral gap between the passbands than the width of the passbands, to provide a collector box for demultiplexing functions.

4. The method of adding and dropping signals of selected wavelength bands to and from a main transmission line for optical signals comprising the steps of:
propagating add/drop wavelength bands along a separate path other than the main transmission line;
establishing first wavelength band selective loops at serial positions along the main transmission line to return signals in the loop to the line if not diverted;

establishing second wavelength band selective loops at serial positions along the add/drop path to return signals in the loop to the path if not diverted; and
diverting signals from one or more selected wavelengths of the first loops to corresponding wavelength ones of the second loops to add and/or drop wavelength bands to or from the main transmission line.

5. The method as set forth in claim 4 above, further including the steps of strongly attenuating signals outside the selected wavelength bands in each of the loops, relative to signals within the selected wavelength bands, and propagating the diverted signals through two loops which filter the signals at the selected wavelength bands twice.

6. The method as set forth in claim 5 above, wherein the wavelength bands comprise individual discrete signal-bearing wavelengths.

7. The method as set forth in claim 5 above, wherein the wavelength bands each comprise a group greater than one of discrete signal bearing wavelengths.

8. The method as set forth in claim 5 above, wherein the wavelength band selective loops number at least two at different serial positions along the main transmission line that are of the same chosen wavelength band such that signals of the chosen wavelength band in the main transmission line can be dropped at a first position and other signals of the chosen wavelength band can later be added at a second position .

9. A programmable router for optical waveguide systems comprising:
a first optical waveguide line having add and drop terminals for propagating signals of different wavelengths to be controllably routed;
a second optical waveguide line for propagating selectively combined ones of the signals at different wavelengths;
a plurality of optical waveguide shunting units disposed in parallel between the first and second optical waveguide lines, each of the shunting units including a controllable crossover switch and a pair of wavelength selective optical filters, each filter of a different pair of the optical waveguide lines being in a different line and the filters of each pair each being responsive to a chosen wavelength, and
a routing control system for operating the crossover switches to selectively add and drop wavelengths at the different units.

10. A router as set forth in claim 9 above, wherein the wavelengths to be routed onto the second optical waveguide line comprise discrete individual signal wavelengths.

11. A router as set forth in claim 10 above, wherein the wavelength selective optical filters are grating enhanced couplers reflecting a selected optical wavelength and wherein the controllable switches comprise dual input and dual output switches having one input and one output coupled across each coupler.

12. A router as set forth in claim 11 above, wherein the grating enhanced couplers pass wavelengths outside the selected wavelength band substantially attenuated and wherein the shunting units pass the selected wavelength through two couplers selective at the same wavelength for double pass filtering of the selected wavelength.

13. A router as set forth in claim 11 above, wherein add/drop signals are propagated on the first optical line in counter-direction to signals on the second optical line such that a dropped signal at a selected wavelength may be supplanted by an added signal at the same wavelength.

14. A router as set forth in claim 13 above, wherein the shunting units intercouple like wavelength couplers arranged in sequentially changing wavelength on each line.

15. A router as set forth in claim 13 above, wherein the shunting units intercouple like wavelength couplers arranged in oppositely changing wavelength sequences on the two lines such that add/drop signals transferred between the two lines traverse the same number of couplers independent of the routing function used.

16. A programmable, wavelength selective router which directs a programmable combination of wavelength channels between optical waveguides, comprising:
a first optical waveguide;
a second optical waveguide;
a first plurality of grating assisted mode couplers characterized by different add/drop wavelengths, each having an input, throughput, add and drop port, the input and throughput ports of said first plurality of grating assisted mode couplers being disposed in serial fashion along said first optical waveguide;

a second plurality of grating assisted mode couplers characterized by different add/drop wavelengths, each having an input, throughput, add and drop port, the input and throughput ports of said second plurality of grating assisted mode couplers being disposed in serial fashion along said second optical waveguide;
a plurality of crossover optical switches, each having a first and second input and a first and second output,
wherein the drop ports of the first plurality of grating assisted mode couplers are individually coupled to the first switch inputs, the add ports of the first plurality of grating assisted mode couplers are individually coupled to the second switch inputs, the drop ports of the second plurality of grating assisted mode couplers are individually coupled to the second switch outputs and the add ports of the second plurality of grating assisted mode couplers are individually coupled to the first switch outputs.

17. A programmable router in accordance with claim 16 comprising further:
a number N of grating assisted mode couplers in the first plurality and N in
the second plurality, and
N crossover optical switches, wherein N is equal for four or eight.

18. A programmable router in accordance with claim 16 whereby the add/drop wavelengths of each pair of grating assisted mode couplers coupled to a particular crossover switch are equal to within 0.1 nm, and wherein the frequency separation between individual add/drop wavelengths is approximately 50, 100 or 200 GHz.

19. A programmable router in accordance with claim 16 wherein the grating assisted mode couplers are cross-connected in a manner that equalizes the loss experienced by each wavelength channel.

20. A programmable router for optical waveguide systems having an add/drop line to and from which different wavelengths are combined or extracted from a common throughput line, comprising:
a number of 2:2 optical crossover switches, each controllable to pass or divert input signals to different outputs in a symmetrical manner;
a number of wavelength selective add/drop filters, each being reflective at a different selected wavelength, a first set thereof being coupled into the add/drop line on one side and a first input/output pair of a different optical switch on the other side, and those of a second set being coupled into the throughput line on one side and the second input/output pair of a different optical switch on the other side, the interconnections of the first set being such that the channels at different add/drop wavelengths are propagated through a like number of add/drop filters regardless of routing,
and a control system for selecting the states of the optical switches.

21. A router for optical signals comprising:
a main optical fiber;
an add/drop optical filter in parallel with the main optical fiber, optical wavelength signals with different wavelengths being propagated in opposite directions on the two fibers; and
a plurality of cross-switching units serially interconnecting the two fibers, each responsive to a selected wavelength and propagating other wavelengths along the two fibers, each cross-switching unit being coupled to controllably change the wavelengths propagated on the main fiber by adding selected wavelength signals from and dropping selected wavelength signals to the add/drop optical fiber.

22. A router as set forth in claim 21 above, wherein the cross-switching units include at least two units that are responsive to the same wavelength, and so positioned along the main optical fiber such that a selected wavelength signal that is dropped at one unit can be added at another.

23. A router as set forth in claim 22 above, including in addition a routing control system for operating the cross-switching units to add and drop selected wavelengths at the main optical fiber.

24. A router as set forth in claim 23 above, wherein the cross-switching units include optical switches having paired terminals that are being controlled to transfer signals between terminals of one pair and terminals of another pair, and wherein the cross-switching units include wavelength responsive couplers having two paired terminals, and non-evanescent interchange regions incoφorating wavelength selective reflective gratings whose periodicities are selected to reflect the selected wavelengths to the adjacent terminal of the same pair while propagating other wavelengths to a terminal of the opposite pair, and the cross-switching units and the couplers are interconnected such that the couplers redundantly diminish the sidebands of the selected wavelengths.

25. A collector box system for separating groups of channels to be added or dropped in an optical wavelength band employing a multitude of grating assisted couplers joined in series comprising:
an optical waveguide; and
a plurality of grating assisted mode couplers, each having an input, throughput, add and drop port, the input and throughput ports of said first plurality of grating assisted mode couplers being disposed in serial fashion along said optical waveguide and being imprinted with an apodized and chiφed grating selected to add and drop a group of sequentially adjacent wavelength channels, each encompassing a different wavelength subband within the overall band.

26. A collector box in accordance with claim 25 wherein the number of sequentially adjacent wavelength channels added or dropped is in the range of 4 to 8, and wherein the frequency spacing of sequentially adjacent wavelength channels is 50, 100 or 200 GHz.

27. A collector box in accordance with claim 25 wherein the wavelengths of said wavelength channels are in the range of 1500 to 1600 nm, wherein the subbands are about 6.6 nm in width, and wherein the spacing between wavelength band edges is less than 2 nm, and wherein the cutoff characteristic of each wavelength band is such that the crosstalk level, or reflectivity of a first grating at the center wavelength of the nearest adjacent wavelength channel outside the wavelength band to be added or dropped, is below -25 dB at less than 1 nm from the wavelength band edge.

28. A network for branching incoming channels in an optical waveguide communication system having many channels into channel subsets each having a number of adjacent closely spaced wavelength channels comprising:
a system of grating assisted add/drop filter units, each coupled to receive the total set of channels and each unit responsive to wavelengths falling only within a selected wavelength band to output such wavelengths as a subset of channels, wherein each filter unit comprises a group of filter units, each having a grating that is selective to a spectral band of wavelengths, and with adjacent band edges exhibiting less than -25 dB crosstalk at crossover points between adjacent bands.

29. A network as set forth in claim 28 above, wherein the gratings have apodized grating responses providing greater than 20 dB add/drop rejection within of the passband.

30. A network as set forth in claim 28 above, wherein the filter units each comprise a number of add/drop filters having reflection gratings, and the grating functions each comprise a band chiφing function and an apodization function.

31. A signal switching unit for selectively directing signals at optical wavelengths from a first optical wave transmission line to a second wave transmission line comprising:
an optical switch having two terminal pairs and selectively controllable to pass signals through from one terminal of a pair to one terminal of the other pair, or alternatively between terminals of the same pair;
first and second reflective optical signal couplers, each having two pairs of terminals and each reflecting a selected wavelength band received at one terminal of a pair to the other terminal of the pair, and passing other wavelengths through to a terminal of the other pair, each of the couplers being interspersed in a different one of the wave transmission lines at a first set of pass-through terminals, the couplers being bi-directional and the selected wavelength bands being alike, and
first and second signal loops, each interconnecting one pass-through terminal set of the optical switch to a pass-through set of a different coupler,
whereby on operation of the switch a selected wavelength band on one of the wave transmission lines can be directed to the other of the wave transmission lines.

32. A switching unit as set forth in claim 31 above, wherein one wave transmission line comprises an add/drop line for a selected wavelength band and the other wave transmission line comprises an input line for multiple wavelengths within the same wavelength band.

33. A switching unit as set forth in claim 32 above, wherein the optical switch is responsive to a substantially wider wavelength band than the signal couplers.

34. A switching unit as set forth in claim 33 above, wherein there are a plurality of switching units coupled between the add/drop line and the input line, wherein each of the signal couplers comprises a grating assisted reflective filter responsive to a selected narrow wavelength band, the bands being different for each unit, and wherein a controller is coupled to the optical switches to provide selected add/drop incremental wavelength band modifications to the input signal.

35. A Bragg grating enhanced coupler including a non-evanescent waist region with an index of refraction grating therein, the coupler having pairs of terminals at opposite ends of the waist region wherein the index of refraction grating has a grating periodicity in the waist region having at least two variations, a first variation distributing wavelength responsiveness over a selected wavelength band, and a second independent variation in which wavelength responsiveness terminates abruptly at the limits of the wavelength band, whereby the wavelength responsiveness is substantially uniform within the selected band and has a shaφ cut off characteristic at the edges of the band.

36. A coupler in accordance with claim 35 above, wherein the first variation is in accordance with:

δndc(z) = 6.5 lo*3 (z/L + π/20 sin(2π z L))

and the second variation is in accordance with:

δnac(z) = 1.2 10-3 cos-^π z/L)

where δnac(z) is the index of refraction modulation envelope and δndC(z) is the background index of refraction variation, z is the position along the grating and L is the grating length.

37. A coupler in accordance with claim 36 above, wherein the length L of the grating is about 15 mm, and wherein the coupler has a responsiveness band of at least about 6 nm and wherein the responsiveness drops to at least -25 dB at 1 nm outside the band limits.

38. A band pass filter for optical signals comprising:
a coupler comprising a pair of optical fibers with a reduced diameter waist region in which the fibers are joined longitudinally in a non-evanescent merged region, the waist region including a grating reflective at a selected wavelength and the coupler including pairs of terminals at each end of the waist region, and the waist region reflecting signals of a selected wavelength input at a first terminal at one end to the other terminal at the same end and passing other wavelengths through to a throughput terminal at the other end, and an optical termination coupled to the throughput terminal.